FR3073111A1 - METHOD AND DEVICE FOR STORING AND SHARING INTEGRATED DATA - Google Patents

Abstract

The present invention relates to a method for sharing data between actors (5) of a network, said method comprising a step of cryptographic data by an asymmetric cryptographic method with double keys, each actor (5) having at least one said double key. The method includes a step of initializing (STP1) a blockchain that includes a step of storing at least one initialization block (26) by a predetermined authority using at least one computer , said at least one initialization block (26) comprising at least one said transaction (36) which includes an identity record (84) of a major player, said authority no longer intervening at the end of the initialization step (STP1) at least outside a step of resetting an actor.

Description

Method and device for storing and sharing integrated data

The present invention relates to a method and a device for storing and sharing integrated data, in particular in the aeronautical and space field.

In the aeronautics and space sector, all kinds of data are exchanged between various natural or legal persons. In particular, data can be exchanged between an aircraft and a system present outside the aircraft.

This data can take various forms. For example, this data may take the form of software or configuration data to be downloaded onto an on-board system of an aircraft, software and flight data which contribute to air operations and to aircraft maintenance activities, software and of data received on board an aircraft for the management of aircraft fleets, of administrative and / or technical and / or operational digital documents. This data can represent any other digital information that can have an impact in terms of flight safety, air or industrial operations, intellectual property, image ...

The data exchanged can be traced to identify their sources and recipients. This data must possibly be available for several different actors, for example various aircraft, various airlines, various government agencies ... In addition, this data must be honest and authentic so as not to cause an incident. In addition, the data to be exchanged may be confidential.

These four conditions prove difficult to obtain. Indeed, computer attacks can aim to modify the data, and can have an impact on the reliability and / or the traceability of the exchanged data.

Furthermore, on an aircraft in flight, data is subject to a risk of loss in the event of a breakdown or accident. When the data is stored on an aircraft storage medium before being transferred to the ground to other actors, an inadvertent destruction of the storage medium can lead to the loss of the stored data.

Some technical solutions consist in authenticating the people, services or equipment that interact with sensitive systems, to know if they are authorized to act or if they are unauthorized elements, possible vectors of attacks. Technical solutions are thus based on the use of digital certificates conforming to the PKIX specification which implements asymmetric cryptographic mechanisms.

These solutions call on a trusted third party who is recognized by the various players in the network. Such a trusted third party is sometimes called a "Certification Authority", in reference to the notion of "digital certificate" used by the technical standard applicable in the matter known by the acronym "PKIX".

According to a solution of this type, a certification authority delivers to each user three pairs of keys, each including a public key and a private key, and the associated certificates. These three key pairs are used respectively to meet authentication, signature and encryption needs. A certificate attests that a couple of keys belong to a particular user. A certificate can for example contain a serial number, the type of signature used, the identification of the trusted third party, dates of issue and validity, the identification of the owner of the keys ... For example, a certificate can be established in accordance with standard X509.

Thus, a user can sign data using a first pair of keys to guarantee the authenticity of data and protect its integrity. The data or a digital fingerprint of this data is signed with the private key of the first pair of keys, to allow verification of this signature by third parties using the certificate and the public key of the first pair of keys.

A user can encrypt data using a second pair of keys to keep it confidential. A user can derive from the private key of the second pair of keys a symmetric key. The data is then encrypted using this symmetric key. This symmetric key is itself encrypted with the recipient's public key. The encrypted data and the encrypted symmetric key are sent to the recipient. The recipient can then decrypt the symmetric key using their private key, and then decrypt the data using the symmetric key.

The third pair of keys can be used for authentication.

For example, a solution of this type is known by the acronym "PKI" corresponding to the English expression "public key infrastructure".

The documents FR 2912578, FR 2922702 illustrate such solutions.

Although attractive, these technical solutions can prove to be difficult to implement.

A PKI-like solution involves the use of a certification authority to manage the various keys and certificates. To guarantee proper key management, cumbersome and complex processes are implemented. For example, a couple of keys have a limited lifespan. Obtaining a couple of replacement keys at the end of this lifespan necessarily involves seeking the certification authority. This certification authority is therefore always in demand.

In addition, the trust placed by users in a solution of this type is in fact linked to the trust placed in the certification authority. A difficulty therefore resides in the difficulty of finding a trusted third party who satisfies all the players, in particular in an international / intercontinental context.

In addition, the use of a centralized certification authority can pose a security problem. If this centralized certification authority is attacked, the security of the entire network is compromised.

In addition, the certification authority may include a receiver. The sequestering entity has the function of sequestering the keys used for data encryption, in order to restore them if necessary. There are multiple reasons for such an entity. Indeed, the loss of a private encryption key by its holder should not be permanent. In addition, an organization may wish to be able to decrypt documents when one of its members is no longer a member. Finally, in some countries, the law requires that encrypted data can be decrypted at the request of the national authorities.

In an international context, this last requirement can pose difficulties since each country tends to wish the sequestration on its own soil of keys encrypting the messages of its nationals.

Furthermore, if a user makes a software manipulation or configuration error during the verification of electronic signatures, the chain of trust making it possible to go back to the root certification authority may in certain cases be compromised.

The technical solutions of making available collected data, for example from aircraft, are more conventional. These solutions can consist in memorizing this data in several physically distinct places. Access to data is guaranteed even in the event of destruction of a storage location. For example, each actor can have their own copy.

However, synchronizing all the data can be tricky. Ensuring that the databases of different actors are up to date can be difficult and expensive.

The document FR3018379 does not belong to the field of the invention, and does not provide any solution to the problem posed. This document is cited for informational purposes only. Likewise, document US 2016/0283920 is known.

The technical solution known as Certcoin is also known. The system known as namecoin aims to manage domain names.

The following websites are also known:

- https://conference.hitb.org/hitbsecconf2013ams/materials/

HugoTeso Aircraft Hacking Practical Aero Series.pdf https://publications.airlines.org/ Spec42 Aviation Industry Standards for Digital Information Security

- https://datatracker.ietf.org/wg/pkix-charter.html https://letsencrypt.Org//2016/09/20/what-it-costs-to-run-lets· encrypt.html.

http://www.zdnet.fr/actualites/piratee-l-autorite-de-certificationdiginotar-est-en-faillite-39764136.htm

- https://threatpost.com/polish-planes-grounded-after-airline-hit-withddos-attack/113412/

- https://bdtechtalks.com/2017/01/11 / 11 / how-blockchain-can-improvecybersecurity /

- https://courses.csail.mit.edU/6.857/2014/f i les / 19-fromknecht-velicannyakoubov-certcoin.pdf

- https://bitcoin.org/bitcoin.pdf

- https://defensecontractormarketing.com/top-1 OO-aerospacecompanies-2015 /

- http://sancy.univ-bpclermont.fr/~lafourcade/PAPERS/PDF/KLL14.pdf

- http://emercoin.com/

The object of the present invention is therefore to propose a method for generating and managing double keys and exchanging data, in particular adapted to the aeronautical and space environment.

The invention relates to a method for storing and sharing integrated data between actors of a network, the method comprising a step of cryptography of the data by an asymmetric cryptographic method with double keys, each actor having at least one said double key.

A blockchain being implemented, a block comprising a digital fingerprint of the block which precedes it in the blockchain and at least one transaction which includes data to be shared, at least one block being an initialization block initializing the chain blocks and at least one block being a registration block for a new actor, at least one said actor being a major actor, at least one said actor being a subordinate actor and at least one said actor being a computer equipment, a said major player being authorized to request membership of said network of a new major player as well as of a new subordinate player and of new IT equipment, a said subordinate player being authorized to request membership of said network only of a new IT equipment, the process includes:

a step of initialization of the block chain which comprises an operation of memorizing said at least one initialization block in the block chain by a predetermined authority using at least one computer, said at least one block initialization comprising at least one said transaction which includes an identity registration of a major player,

a step for accepting a new actor which includes an operation of memorizing at least one block for registering a new actor in the block chain by a said major or subordinate actor using at least one computer, said at least one new actor registration block comprising at least one said transaction which includes an identity registration of said new actor,

Said identity record of a major / subordinate actor or IT equipment comprising identification data of this major actor / subordinate actor or IT equipment which includes at least one identifier of this major actor / subordinate actor or IT equipment, a public key of a double key called the double signature key of this major player / subordinate player or IT equipment intended for signing data, a public key of a double key called the double encryption keys of this major player / subordinate player or IT equipment intended for the signature of data, a public key of a double key called double revocation keys of this major player / subordinate actor or IT equipment intended for the revocation of at least the double encryption keys and the double keys of signature of this major player / subordinate player or IT equipment, said car no longer intervening at the end of the initialization stage or only intervening during a stage of reinitialization of an actor following a revocation of the double revocation keys of this actor.

The expression "each actor being associated with a double key comprising a private key and a public key" means that each actor has a private key known only to him, and a public key which corresponds to the private key.

The expression "block comprising a digital fingerprint of the block which precedes it" means that with the exception of the first block of the block chain, each block comprises the digital fingerprint of the block which precedes it in the block chain.

The expression “major player” designates a natural or legal person provided with at least one computer connected to the network to apply the process of the invention. Likewise, the expression "subordinate actor" designates a natural or legal person provided with at least one computer connected to the network to apply the method of the invention. The term “computer equipment” designates equipment connected to the network, such as for example an aircraft computer.

As a reminder, a blockchain is known by the English term "BlockChain". A blockchain is notably used in the financial sector and in particular in the bitcoin currency exchange system. Details on BlockChain technology can be found on the internet, for example at the following addresses https://blockchainfrance.net/, https://fr.wikipedia.org/wiki/Cha%C3%AEne_de_blocs, https: // fr.wikipedia.Org/wiki/Bitcoin#La_cha.C3.AEne_de_blocs

A blockchain is a distributed database that maintains a list of data protected against tampering or modification. The transactions represent the exchanges between the users of the network, and are stored within the blocks of the block chain. The different transactions recorded are grouped in blocks. After recording the recent transactions, a new block is mined by an actor qualified as a miner, ie generated, and analyzed. If the block is valid, the block can be time stamped and added to the block chain. The transactions are then visible throughout the network. Once added to the blockchain, a block can no longer be modified or deleted, which guarantees the authenticity and security of the network.

The present invention uses blockchain technology not to exchange currencies but at least to memorize the public keys of the double keys of the actors of a computer network. This network can be a private network and can bring together actors in the aeronautical and space field, each actor representing a node of the computer network and comprising at least one computer connected to the computer network. The blockchain is then stored on at least one computer of certain actors or even of all the actors.

The blockchain can be described as an “aero” blockchain when used within a network of actors in the aeronautics and space sector.

This block chain can be constructed in the usual way. The block construction protocol can be a protocol known to those skilled in the art implementing a computer. This protocol can be combined with a consensus method. A new block is inserted into the block chain only if a referencing number of actors have validated the block, for example via the processes known as the "proof of stake" or under the expression "proof of work> >.

The frequency of creation of the blocks in the block chain can be defined according to the number of actors on a time basis, or according to a minimum number of transactions to be contained in a block.

If the blockchain contains too many blocks to allow a complete copy of the blockchain on a laptop computer for example, the process can be based on the technology of cryptographic accumulators.

According to the invention, the block chain comprises at least one initialization block created and stored by a predetermined authority. This predetermined authority only intervenes at this stage of the process unlike a usual PKI system, or only intervenes at this stage of the process and to reinitialize an actor during a reinitialization stage following a compromise of a double key revocation of this actor.

According to one aspect, in the event of compromise of the private key of revocation of an actor, a complete cycle of new registration of this actor can be undertaken either only by major actors, or only by a predetermined authority and for example the authority requested during the initialization stage, either by major players and / or a predetermined authority.

The initialization of the blockchain is carried out by an authority which mines the first blocks of the blockchain. These first blocks are blocks called "initialization blocks" for convenience and contain the identity records of major players in the network. These major players are players with the power to register all types of players.

This authority can be a known body, for example one of the bodies known by the acronyms ICAO, FAA or EASA. Possibly, this authority can also take the form of a consortium of international companies perfectly identified as major players to avoid centralizing the power of initialization of the blockchain.

Following this initialization, major players can memorize acceptance blocks from a new player to introduce a new player, this new player can be a major player, a subordinate player or IT equipment. Registered subordinate actors can memorize acceptance blocks of a new actor only to introduce computer equipment into the network. “IT equipment” type actors cannot register new actors.

The registration of computer equipment is thus always done under the responsibility of a natural or legal person who is himself already registered and who is responsible for the actions related to this computer equipment.

Each identity record relating to an actor is visible to all the actors of the network and comprises at least three public keys of three double keys respectively for signature, encryption and revocation. The private keys of the double keys respectively for signing, encryption and revocation of an actor are in the possession of this actor.

In addition, an identity record includes at least one piece of information identifying the actor concerned. Such information may include an address of the actor, the name of the actor whether this actor is a legal or natural person or even IT equipment, an registration number of the actor ...

Consequently, the actors of the network can refer directly to the block chain memorized on their computers to obtain the public keys of the different actors as well as the information identifying them.

In addition, the key management is carried out by the actors themselves by requesting the blockchain at the end of the initialization step.

As a result, the notion of trusted third party may disappear completely at the end of the initialization step.

In addition, network players can then identify themselves by consulting the blockchain with a high level of assurance, the mechanisms for creating and managing keys being implemented in a decentralized, resilient and transparent manner.

All network players can also verify for themselves with a computer the reliability and authenticity of electronic transactions transmitted in the blockchain using the public keys available online in the blockchain.

In addition, the transactions stored in the block chain can include various data exchanged between the actors, and in particular aeronautical data as described above. This data can be signed or encrypted as needed using respectively the double signature and encryption keys.

The double revocation keys allows an actor to revoke and renew if necessary the double signature keys and the double encryption keys of this actor, in particular when these double keys are compromised or expired according to a digital identity management policy of the block chain.

This process may further include one or more of the following characteristics.

Said identity record of a major actor / subordinate actor or IT equipment can include an identification of a cryptographic signature algorithm associated with said double signature keys of this major actor / subordinate actor or IT equipment, an identification of a cryptographic encryption algorithm associated with said double encryption keys of this major player / subordinate player or IT equipment, an identification of a cryptographic revocation algorithm associated with said double revocation keys of this major player / subordinate player or IT equipment.

Thus, each actor in the network can easily determine the cryptographic algorithm to be used by consulting the blockchain with a computer.

According to one aspect, a said identity registration of a major actor / subordinate actor or IT equipment can include a validity date of said double signature keys of this major actor / subordinate actor or IT equipment, and a validity date of said double encryption keys of this major player / subordinate player or IT equipment.

Each validity date can include an expiration date or even a date of activation of the associated double key. This data is accessible to all stakeholders by consulting the blockchain with a computer.

According to one aspect, a so-called identity record of a major actor / subordinate actor or IT equipment can include a level of importance of this major actor / subordinate actor or IT equipment used during a block validation operation. by proof of stake created by this major player / subordinate player or IT equipment.

When a transaction is issued by an actor in the network, each actor can take the form of a miner to undermine a block. This block is then analyzed by computer by at least one other actor in order to be validated or invalidated. If the block is invalidated, the transaction is not recorded. On the other hand, if the block is validated, this block is memorized in the last position in the block chain.

Validation can be carried out via a consensus method, for example by proof of stake. The system known as validation of blocks by proof of stake favors the actors who have the most interests in the system through the level of importance. This level of importance can be measured based on annual results by company for example.

By way of illustration, two levels of importance can be defined, namely a high level of importance and a low level of importance. A block mined by an actor with a high level of importance can be introduced into the block chain after validation by another actor. On the other hand, a block mined by an actor having a low level of importance can be introduced into the block chain after validation of an actor having a high level of importance or after validation by at least two actors having a level of low importance.

Alternatively, a method of validating a “proof of work” type block can be implemented. For example, minor actors can be remunerated through paid subscriptions from actors, for example.

Alternatively, a block proof validation method of "proof of work" - "proof of stake" is possible. For example, the criteria applied to the proof of work method vary depending on the level of importance of the minor.

According to one aspect, at least one said identifier of a major actor / subordinate actor or IT equipment can include a name of this major actor / subordinate actor or IT equipment or an address of this major actor / subordinate actor or IT equipment.

The address can take the form of a physical address, or an address of an electronic mailbox for example.

A role of this major actor / subordinate actor or IT equipment in the network can also be defined, such as for example an aircraft manufacturer role, a maintenance technician role, a merchant role, an operational role ... .

According to one aspect, the identification data of an actor can include a level of assurance of this actor making it possible to indicate how this actor has been identified.

For example, the registration of new major players with the highest level of insurance is done on presentation of identity papers. For the registration of a subordinate actor with a lower level of assurance, an address of an electronic mailbox corresponding to a domain name verified by another blockchain may be sufficient. For example a string of type NameCoin described for example on the site https://namecoin.org/ can be used.

Thus, the actor who transmits a transaction to register a new actor indicates the level of assurance of this new actor.

According to one aspect, a said identity record of a major player / subordinate player or IT equipment includes a public key of a double key called "double authentication keys" of this major player / subordinate player or IT equipment intended for authentication of this major player / subordinate player or IT equipment.

An identity record can thus include several of the following attributes for an actor: identity of the actor (natural or legal person; IT equipment); address, role, "online" public key with a double signature key, "online" public key with a double encryption key, "online" public key with a double authentication key, “offline” public key of a double revocation key, associated cryptographic algorithms, level of assurance of registration, level of importance in the block validation process, validity dates of the double keys. This collection of attributes can be completed or modified according to the standards in force.

According to one aspect, if for a said major actor / subordinate actor or IT equipment at least two blocks of said block chain contain distinct information relating to the same data identifying this major actor / subordinate actor or IT equipment, said at at least two blocks having been inserted into said block chain at different times, said data identifying this major player / subordinate player or computer equipment which is in force at a current time presents the information contained in said at least two blocks on more recent.

The identification data of an actor may change. Therefore, to obtain the valid identification data at a given time, it is enough to access the blockchain with a computer. The most recent identification data is in fact the identification data in force.

For example, two different blocks contain the public signature key of an actor. The public signature key of an actor in force at a current time is the public signature key contained in the most recent block.

In addition, an actor can always have access to the old identification data of an actor if necessary, for example to decrypt the data contained in a transaction prior to the issuance of the new identification data.

According to one aspect, the operation of memorizing at least one registration block of a new actor can include the following operations:

- emission in said network of a request including a said identity record of said new actor, by executing with a computer of a recorded actor instructions stored in a memory for example,

- mining by a said actor of the block chain of a said identification block of a new actor including said identity record of said new actor, by executing with a computer of the minor instructions stored in a memory for example,

- validation of said block by at least one actor in the block chain distinct from the actor having carried out said mining, by executing with a computer instructions stored in a memory for example,

- and storage after said validation of said block in the block chain, by executing with a computer instructions stored in a memory for example.

In general, each separate transaction of an identity record made during the initialization step can follow this process. A transaction is sent over the network by an actor using a computer applying stored instructions. An actor playing the role of a miner receives the transaction and creates a block including the transaction with a computer by applying a predetermined mining algorithm. At least one other actor validates the block using a computer by checking predetermined points, possibly automatically using stored instructions, then the minor memorizes the block in the block chain of his computer when the required validations are acquired. The blockchain is then duplicated for example on each of the computers of the actors of the network, possibly automatically each computer consulting the network to update the blockchain.

In particular, a transaction relating to an identity registration is verified by: verifying the identity of the new actor according to the registration policy, verifying the cryptographic algorithms used, verifying the possession by the new actor of the private keys associated with the public keys of the recording.

According to one aspect, the method can include a key modification step during which a said actor modifies at least one said double key belonging to him including a valid public key and a valid private key, said modification step comprising the following operations:

- generation of a new double key including a new public key and a new private key, by executing with a computer of the actor concerned instructions stored in a memory for example,

- creation and transmission to the network, by executing with a computer of the actor concerned instructions stored in a memory for example, of a transaction called "identification transaction" comprising an identifier of said actor and the public key in force as well that the new public key and a cryptographic algorithm associated with this new public key, said identification transaction comprising said new public key and said identifier digitally signed with the current private key as well as said identifier digitally signed with the new private key,

- insertion of said identification transaction in a new block of the block chain, by executing with at least one computer of another actor instructions stored in a memory for example.

Thus, an actor can modify his double signature keys, his double encryption keys or if necessary his double authentication keys by applying this process. An actor does not need to use a third party authority to make this change.

To insert an identification transaction in a new block, validation of the identification transaction may be required.

According to one aspect, said operation of inserting said identification transaction in a new block of the block chain can then include:

- a phase of verification of said transaction Identification through at least one actor of said network which includes:

o a verification that said public key in force belongs to the actor having said identifier by consulting the blockchain with a computer, by executing with a computer of a minor actor instructions stored in a memory for example, o a first decryption with a computer and the public key in force of said new public key and of said identifier digitally signed by the private key in force, by executing with a computer of a minor actor instructions stored in a memory for example, o a determination of a first equivalence between said new public key and said identifier obtained by said first decryption and respectively the current public key and the identifier stored in the identification transaction, by executing with a computer of a minor actor instructions stored in a memory for example, o a second decryption with a computer r and the new public key of said identifier digitally signed by the new private key, by executing with a computer of a minor actor instructions stored in a memory for example, o a determination of a second equivalence between said identifier obtained by said second decryption and the identifier stored in the identification transaction, by executing with a computer of a minor actor instructions stored in a memory for example, o a validation of said identification transaction in the presence of the first equivalence and the second equivalence, by executing with a computer of a minor actor instructions memorized in a memory for example,

- a phase of creating a new block including said identification transaction in the event of validation, by executing with a computer of a minor actor instructions stored in a memory for example.

The identity transaction issued is thus verified during the verification phase by an actor called "minor actor" different from the actor having issued the identity transaction. In particular, this minor actor checks at least: the identity-public key correspondence in force by interrogation with a computer of the last block of the block chain containing the public key concerned, the signature made with the public key in force, the signature made with the new public key.

Once these verifications have been made, a new block containing the identification transaction may be mined by the minor actor. When at least one actor has validated the new block mined by a consensus method, the new block is memorized in the block chain of the minor actor. The blockchain is moreover duplicated on each of the computers of the actors of the network.

According to one aspect, the method may include a revocation step during which a said actor revokes at least one said double key belonging to him including a valid public key and a valid private key, said revocation step comprising the following operations:

- generation of a new double key including a new public key and a new private key, by executing with a computer of the actor concerned instructions stored in a memory for example,

- creation and transmission, by executing with a computer of the actor concerned instructions stored in a memory for example, towards the network of a revocation transaction comprising an identifier of said actor and the public revocation key of this actor and the key current public order to be revoked as well as the new public key and a cryptographic algorithm associated with this new public key, said revocation transaction comprising said new public key and said identifier digitally signed with the private revocation key as well as said identifier digitally signed with the new private key,

- insertion of said revocation transaction in a new block of the block chain, by executing with at least one computer of a minor actor instructions stored in a memory for example.

Thus, an actor can revoke his double signature keys, his double encryption keys or if necessary his double authentication keys by applying this process. An actor does not need to use a third party authority to make this change.

To be inserted in a new block, validation of the revocation transaction may be required.

According to one aspect, said operation of inserting said revocation transaction in a new block of the block chain can include:

- a phase of verification of said revocation transaction by at least one actor of said network which includes:

o a verification that said public revocation key belongs to the actor having said identifier by consulting the blockchain with a computer, by executing with a computer of a minor actor instructions stored in a memory for example, o a first decryption with a computer and the public revocation key of said new public key and of said identifier digitally signed by the private revocation key, by executing with a computer of a minor actor instructions stored in a memory for example, o a determination of a first equivalence between said new public key and said identifier obtained by said first decryption and respectively the current public key and the identifier stored in the revocation transaction, by executing instructions stored in a memory with a computer of a minor actor for example, o a second decryption with an o computer and the new public key of said identifier digitally signed by the new private key, by executing with a computer of a minor actor instructions stored in a memory for example, o a determination of a second equivalence between said identifier obtained by said second decryption and the identifier stored in the revocation transaction, by executing with a computer of a minor actor instructions stored in a memory for example, o validation of said new block in the presence of the first equivalence and the second equivalence, in performing with a computer of a minor actor of

instructions example, stored in a memory through a phase of creation of a new block including said

revocation transaction in case of validation, by executing with a computer of a minor actor instructions stored in a memory for example.

The revocation transaction issued is thus verified during the verification phase by an actor called "minor actor" different from the actor having issued the identity transaction. Once the required verifications have been made, a new block containing the revocation transaction may be undermined by the minor actor. When at least one actor has validated the new block mined by a consensus method, the new block is memorized in the block chain of the minor actor. The blockchain is moreover duplicated on each of the computers of the actors of the network.

According to one aspect, the method can comprise a step of sequestering keys which comprises the following operations for a said actor:

- creation of a copy of the double encryption keys for this actor, by executing with a computer instructions stored in a memory for example,

- encryption of the copy with a public key of a double encryption key of a security officer of said actor to obtain an encrypted element, by executing with a computer instructions stored in a memory for example,

- then encryption of the element encrypted with a public key encryption of a major actor different from said actor, by executing with a computer instructions stored in a memory for example.

No dedicated escrow authority is then required. The recourse to the sequestration key of a network actor is done on the basis of a double agreement of the security officer of this actor, plus the agreement of the major actor possessing the private key corresponding to the public encryption key used to encrypt the encrypted item.

An alternative will be based on the principle known under the English expression "shared secret" developed by Adi Shamir and described at the following address:

https://en.wikipedia.org/wiki/Shamir's_Secret_Sharing

According to one aspect, in order to digitally encrypt data and transmit them to a said actor called "recipient", the data being contained in a transaction called "data transaction", the method can include the following operations: consultation of the block chain for obtain the current encryption public key assigned to the recipient of the data, and encryption of the data with said recipient's public encryption key.

To digitally sign data, an actor called "sender" uses his private signature key to digitally sign the data, another actor says "recipient" consulting said blockchain to obtain the sender's public signature key in order to decrypt the data signed by the sender.

In addition, the data exchanged can be written in blocks of the block chain to be traced and stored in a decentralized manner.

Depending on the type of implementation chosen, the blocks can contain a fingerprint of the data exchanged and / or the data exchanged themselves.

To record in the block chain a transaction called "signed data transaction", said signed data transaction comprising data to be exchanged which are digitally signed, the data to be exchanged including original data or a digital fingerprint of the original data called "first emission fingerprint ”obtained by a hashing method, the method can include the following operations, possibly carried out using a computer executing stored instructions:

- encryption of the data to be exchanged which is to be digitally signed by signing it with the private signature key of a said actor called "sender", to obtain said data to be exchanged which is digitally signed,

- sending to the network of the signed data transaction including the data to be exchanged which are digitally signed,

- creation of a block called "new block" by a said actor called "minor", said new block comprising at least one digital fingerprint of the last block in the block chain and said signed data transaction,

- validation of the new block by at least one said actor,

- insertion of the new block in the block chain after said validation.

Such a signed data transaction may then contain a number, the identity of the issuer, the date and time of the transaction, the type of transaction, the data fingerprint or the original data signed by the issuer.

Original data can be processed to be entered in one or more blocks depending on their sizes.

Alternatively, the original data is transmitted in the form of a digital fingerprint, for example by applying a known hashing algorithm such as the SHA256 algorithm. In this case, it is not the original signed data which is written in a block but a digital fingerprint signed with this original data. Optionally, the original data can be transmitted by another communication channel, possibly not secure, or with the digital fingerprint. In this type of implementation, the original data can reach the recipient with the corresponding registration number in order to be able to find this registration in the block chain.

According to one aspect and when the data to be exchanged takes the form of a said first transmission fingerprint, said miner having received said original data, the method includes a verification operation carried out before building the new block, possibly using from a computer executing stored instructions. The verification operation includes the operations of:

- consultation of said blockchain to obtain the public signature key in force of the sender,

- decryption, with the sender's public signature key in force, of the data to be exchanged which is digitally signed to obtain the said first transmission fingerprint,

- creation of a digital fingerprint called "control fingerprint" of the original data,

- comparison of the control print and said first transmission print,

- rejection of the transaction in the presence of a difference between the control print and said first transmission print.

A transaction can thus be validated before insertion into a block by verifying the signature and the address of the owner through this procedure. If the control fingerprint and said first transmission fingerprint differ, the minor can deduce that the data to be exchanged were not correctly signed. The minor then rejects the transaction, for example by memorizing it elsewhere.

Optionally, the minor can also verify that the transaction date corresponds to the current date.

When the data to be exchanged takes the form of a so-called first transmission fingerprint, a recipient can do the following:

- verification of said signed data transaction, possibly using a computer executing stored instructions:

o by consulting said blockchain to obtain the public signature key in force from the sender, o by decrypting, with the public signature key in force from the sender, the data to be exchanged which are digitally signed to obtain said first transmission fingerprint, o by making a digital fingerprint known as the "control fingerprint" of the original data, o by comparing the control fingerprint and said first transmission fingerprint,

- verification that the block of the block chain containing said transaction of signed data has been validated, by executing with a computer instructions stored in a memory for example,

- disregarding said signed data transaction if the control fingerprint and said first transmission fingerprint are different or if said block of the block chain containing said signed data transaction has not been validated.

So when a recipient wants to ensure the authenticity and integrity of data recorded and received, this recipient calculates the footprint of the original data and compares it with the footprint contained in the appropriate block. The other information of the recording does not have to be checked because it was already checked before the mining of the corresponding block.

According to one aspect, to record in the block chain a transaction called "encrypted data transaction", said encrypted data transaction comprising data to be exchanged which is digitally encrypted, the data to be exchanged including original data or a fingerprint digital source data called "second transmission fingerprint" obtained by a hash method, the encrypted data transaction being intended for a said actor called "recipient", the method includes the following operations, possibly performed with stored instructions :

using a computer running

- consulting the blockchain to obtain the current public encryption key assigned to the recipient,

- creation of a symmetric key and encryption of the data to be exchanged with this symmetric key to obtain data to be exchanged digitally encrypted with said symmetric key

encryption of the symmetric key using the recipient's public encryption key to obtain a symmetric key digitally encrypted with said public key,

sending the encrypted data transaction to the network, said encrypted data transaction including said digitally encrypted exchange data with said symmetric key and said symmetric key encrypted digitally with said recipient's public key,

- creation of a block called "new block" by an actor called "minor", said new block comprising at least one imprint of the last block of the block chain, said encrypted data transaction,

- validation of the new block by at least one actor,

- insertion of the new block in the block chain.

When the data to be exchanged takes the form of the second transmission fingerprint, a recipient having received the original data, said method comprises the following operations, possibly using a computer executing stored instructions:

- verification of said encrypted data transaction by:

o decryption using the private encryption key in force of the recipient of the symmetric key encrypted with said public encryption key of the recipient, o decryption using said symmetric key of the data to be exchanged encrypted with said symmetric key to obtain the second fingerprint transmission, o production of a digital fingerprint known as the "verification fingerprint" of the original data, o comparison of the verification fingerprint and said second transmission fingerprint,

- disregarding said encrypted data transaction if the verification fingerprint and said second transmission fingerprint are different.

In one aspect, at least one data transaction includes the identity of the sender and / or a registration number and / or a date.

Furthermore, the method makes it possible to automate certain actions. This property is designated under the English name "Smart Contract".

For example, a maintenance procedure may require the application of binding procedures to download new software to be implemented on an aircraft. An operator must verify the authenticity and integrity of the software to be downloaded on board the avionics system.

When the data to be downloaded is present in the blockchain of the invention, this data to be downloaded has in fact been verified. The maintenance operations required for this download were therefore carried out upstream, which facilitates the operator's work.

The method can also make it possible to give access to certain resources according to the role and / or the level of assurance of an actor registered in his identity registration.

In addition to a method, the invention relates to a data exchange system. This data exchange system comprises for each actor of the network at least one computer for implementing this method, at least one computer of at least one actor memorizing the block chain.

The invention and its advantages will appear in more detail in the context of the description which follows with an example given by way of illustration with reference to the single figure. This single figure represents a data exchange system according to the invention.

Figure 1 shows a data exchange system 1 within a computer network 2. This network 2 can be a private network. According to the illustrated example, network 2 brings together actors 5 from the aeronautics and space field. However, the invention is applicable to other fields, and for example to the automobile field, to the maritime field, etc. In the context of a network in the aeronautical and space field, the actors 5 can be aircraft manufacturers, operators using these aircraft, State organizations, manufacturers' suppliers, aircraft ...

Actors can be grouped into several groups according to their rights within the network. Thus, the players in the network are divided into major players, subordinate players and IT equipment, the expressions major players / subordinate players / IT equipment being used for convenience to distinguish these different groups of players. The term "actor" used alone can thus designate a major actor or a subordinate actor or IT equipment. A major player has the power to register a new player in the network, which can be another major player or a subordinate player or IT equipment. A subordinate actor has the power to register only IT equipment in the network. Finally, computer equipment is an electronic device capable of communicating with other actors, such as an on-board computer of an aircraft for example.

Each actor 5 can comprise at least one computer 10 connected to the network, this computer 10 executing stored instructions for implementing the method according to the invention, for example through usual software, logic circuits, etc. The computers of the actors communicate with each other and additionally have a memory unit.

This process implements blockchain technology. Thus, the network uses a block chain 20. This block chain 20 is stored in a memory of computers 10 of actors called "miners" for convenience. According to a variant, all the actors represent nodes of the network 2 and memorize the block chain 20. In addition, each actor 5 can use a computer program stored on his computer to consult the block chain 20, regardless of where this chain of blocks is memorized.

Conventionally, the block chain 20 comprises a plurality of blocks 25, one after the other. According to the example shown, the block chain 20 comprises at a current instant five blocks 251, 252, 253, 254, 255 extending from a first block 251 to the last block 255 created.

Each block 25 includes at least one transaction 35. Each transaction 35 includes data stored and made available to the network. This data can take the form of data as such, or a digital fingerprint of this data. An actor's computer 10 can in fact include hashing software for transforming data in order to obtain a digital fingerprint of this data by applying a conventional hashing algorithm. Such a digital fingerprint is sometimes called a "hash". Thus, the data can take the form of a computer file for example, or of a digital imprint of this computer file.

When transaction 35 includes the digital fingerprint of a data item, the data as such can also be included in the transaction. For example, a transaction includes computer software to be carried on an aircraft and a digital fingerprint of this computer software.

In addition, at least one transaction 35 may include information dating from the issuance of transaction 35, and / or the identity of the actor 5 having issued the transaction with his computer and / or a registration number which makes it possible to easily find the transaction.

Furthermore, at least one block 25 can include information 40 dating from the creation of this block 25.

Common software and time stamping methods can be used.

In addition, each block 25 may include a measure 50 of an amount of work that was required to produce the new block. The creation of a block can be undertaken by a computer 10 of the network 2 using a conventional consensus method, for example the method called "proof of work". Such a measure is sometimes called "nonce". Alternatively or additionally, a consensus method by proof of stake can be undertaken.

Furthermore, each different block of the first block 251 has a digital imprint 30 of the previous block. Thus, the second block 252 has a digital imprint of the first block 251, and so on.

According to the method of the invention, the network can make it possible to encrypt the data exchanged between the actors, by digitally signing the data according to a usual method using computers 10 or by digitally encrypting the data according to a usual method. using computers 10. In particular, the method may aim to use an asymmetric dual key cryptographic method. Each actor 5 is thus in possession of several double keys which each include a private key which corresponds to a public key, the private key / public key pair forming an asymmetric double key granted to this actor. The private key of an actor is except incident known only to this actor, while the public key is visible by the other actors.

Consequently, the method applied by the data exchange system 1 then includes an initialization step STP1 aimed at initializing the block chain.

During this initialization step STP1, a predetermined authority intervenes punctually to mine the first block 251 of the block chain with a computer, and possibly one or more blocks following this first block 251. These blocks mined by the predetermined authority are called for convenience "initialization blocks 26" to be easily distinguished from other blocks in the block chain.

The predetermined authority inserts with a computer into each initialization block 26 at least one transaction called for convenience "initialization transaction 36" by applying a usual algorithm.

This initialization transaction 36 includes an identity record 84 assigned to an actor. Each actor identified in an identity record of an initialization transaction 36 is called a "major actor" to be distinguished from the other actors.

The initialization transaction 36 can also include a registration number 81, the identity 82 of the authority, dating information 83 of the initialization transaction 36 may include the date or even the time of this transaction. initialization 36 ...

According to one aspect, an identity record 84 of an actor comprising identification data of this actor which includes at least one identifier A, B, C of this actor. An identifier of an actor can take the form of a name A of this actor, an address B of this actor or even a role C of this actor within the network.

In addition, the identification data of this actor includes a public key D of a double key called the double signature keys of this actor, a public key E of a double key called the double encryption keys of this actor, a key public F of a double key called double revocation key for this actor.

Optionally, the identification data of this actor includes a public key G of a double key called double authentication keys.

Optionally, the identification data of this actor includes an identification H of the cryptographic algorithms associated with these double keys D, E, F, G, namely respectively an identification of a cryptographic signature algorithm associated with said double signature keys of this actor, an identification of a cryptographic encryption algorithm associated with said double encryption keys, an identification of a cryptographic revocation algorithm, and an identification of a cryptographic authentication algorithm.

Optionally, the identification data of this actor includes a validity date I of certain double keys, namely respectively a validity date of said double signature keys, a validity date of said double encryption keys and a validity date of said double authentication keys.

Optionally, the identification data of this actor includes a level of importance J of this actor and / or a level of assurance K of this actor.

To implement the initialization step, the predetermined authority can execute instructions stored on a computer. Consequently, the predetermined authority activates software applying a usual algorithm within a computer to undermine each initialization block, by placing in each initialization block at least one digital fingerprint of the last block of the block chain and one or more identity record (s) relating respectively to one or more major player (s). Optionally, the identification data can be digitally signed with a private key of a double key which belongs to the predetermined authority.

The predetermined authority no longer intervenes at the end of this initialization stage, or can intervene punctually only during a reinitialization stage.

In addition, at the end of this initialization step, the registration of new actors is carried out by implementing a step of acceptance of a new STP2 actor. This step is illustrated by the second block 252 of the block chain. The step of accepting a new actor STP2 includes an operation of memorizing at least one block of registration of a new actor 29 by a so-called major or subordinate actor using at least one computer. Such a registration block for a new actor 29 notably comprises at least one said transaction 34 which includes an identity record for said new actor.

To memorize a new actor, an actor already registered requires the execution of instructions memorized on his computer to send in said network a request including an identity record 84 of the new actor.

Another actor in the network mines a block of a so-called new actor identification block 29 which includes this identity record 84 of the new actor, by executing instructions stored on his computer. Possibly the network operator who mines the block performs checks before mining the block. For example, this actor verifies the identity of the new actor and / or verifies the cryptographic algorithms used and / or verifies the possession by the new actor of the private keys associated with the public keys of the recording. If an error occurs, the transaction is ignored. Verifications can be automated by being performed by a computer.

If the identification block of a new actor 29 is mined, this identification block of a new actor 29 must then be validated by at least one actor in the block chain distinct from the actor having carried out said mining.

For example, the identification block is sent according to the arrows F1 in the network for validation according to usual methods by at least one actor. Validation by a predetermined number of actors may be required. For example, the validation of a block may require the validation of the block by at least two actors housed on two different continents. The proof of stake method can be implemented using the level of importance of the network players, if necessary. When the new block is validated by an actor, this actor sends this information according to the arrows F2 in the network using a computer and suitable software.

After validation, the identification block of a new actor 29 is stored in the block chain. The blockchain can be automatically duplicated on each of the computers on the network in the usual way.

In addition, the identification data can also be modified according to an embodiment.

Thus, the method can include a modification step

STP3 illustrated with the third block 253. During this stage of modification STP3, an actor 5 can modify his identification data by replacing the identification data in force of this actor called for convenience “old identification data”, by identification data for convenience, "new identification data".

During a key modification step STP3, an actor modifies at least one so-called double key belonging to him including a public key in force to be modified and a private key in force to be modified. This modification can be undertaken if necessary before the expiration of a validity date associated with the double keys, for example.

Thus, an actor can request a computer to execute stored instructions in order to generate a new double key including a new public key and a new private key. This actor can request a computer to execute stored instructions in order to create and send to the network an identification transaction 87 comprising an identifier A, B, C of said actor and the public key in force as well as the new public key and an algorithm. cryptographic associated with this new public key. The identification transaction includes said new public key and said digitally signed identifier with the current private key as well as said digitally signed identifier with the new private key. This identification transaction can then be inserted by a minor in the usual way in a new block of the block chain, the third block according to the example given.

To insert the identification transaction in a new block, the minor can first check this identification transaction. Thus, the minor requests a computer to execute instructions making it possible to verify that the public key in force belongs to the actor having said identifier by consulting the blockchain with a computer. In addition, the minor performs a first decryption with a computer of the new public key and the digitally signed identifier using the current public key, then determines the presence or absence of a first equivalence between said new public key and said identifier obtained by said first decryption and respectively the current public key and the identifier stored in the identification transaction.

The minor performs a second decryption with a computer of the digitally signed identifier using the new public key, then determines the presence or absence of a second equivalence between said identifier obtained by said second decryption and the identifier stored in the identification transaction.

The miner validates the identification transaction in the presence of the first equivalence and the second equivalence, and then mines the new block according to a usual method.

This new block is introduced in the usual way in the block chain, possibly by applying a consensus method to require the validation of a referencing number of actors.

Likewise, the method can also include an STP4 revocation step to revoke at least a double key of an actor including a public key in force to be revoked and a private key in force to be revoked.

Thus, an actor can request a computer to execute stored instructions in order to generate a new double key including a new public key and a new private key. This actor can request a computer to execute stored instructions in order to create and send to the network a revocation transaction 88 comprising an identifier A, B, C of said actor, the public revocation key of this actor and the public key in force as well. as the new public key and a cryptographic algorithm associated with this new public key. The revocation transaction includes said new public key and said digitally signed identifier with the private revocation key as well as said digitally signed identifier with the new private key. This revocation transaction can then be inserted by a minor in the usual way in a new block of the block chain, the third block according to the example given.

To insert the revocation transaction in a new block, the minor can first check this revocation transaction. Thus, the minor requests a computer to execute instructions making it possible to verify that the public revocation key belongs to the actor having said identifier by consulting the blockchain with a computer. In addition, the minor performs a first decryption with a computer of the new digitally signed public key and identifier using the public revocation key, then determines the presence or absence of a first equivalence between said new public key and said identifier obtained by said first decryption and respectively the current public key and the identifier stored in the revocation transaction.

The minor performs a second decryption with a computer of the digitally signed identifier using the new public key, then determines the presence or absence of a second equivalence between said identifier obtained by said second decryption and the identifier stored in the revocation transaction.

The minor validates the revocation transaction in the presence of the first equivalence and the second equivalence, and then mines the new block according to a usual method.

The blockchain can also store data to be exchanged which differs from the identification data.

Thus, a transaction called "data transaction 37" for convenience may contain data called "data to be exchanged" of another order, for example aeronautical data.

To digitally sign data, an actor called "sender" requests a computer using his private signature key to digitally sign the data, using a usual algorithm for example. Another actor called "recipient" can then consult said block chain with a computer program of a computer 10 to obtain the public signature key of the sender in order to decrypt the data signed by the sender.

For example, the method makes it possible to record in the block chain a transaction known as a “signed data transaction” during a step STP5. The signed data transaction includes digitally signed data to be exchanged, the data to be exchanged including original data 85 and / or a digital fingerprint of the original data called "first transmission fingerprint 86".

A sender can then encrypt the data to be exchanged by signing it with his private key to obtain data called "signed data to be exchanged".

According to an option, a sender can sign the original data to obtain the signed data to be exchanged.

According to another option, the sender uses a usual hashing algorithm with a computer to obtain the first send fingerprint 86. The sender then signs with his private signature key this first send fingerprint to obtain the data to be exchanged signed. The signed data transaction can then include the signed data to be exchanged in the form of a first signed transmission fingerprint. The original unsigned data can also be included in the transaction or transmitted by another channel to a recipient, for example from hand to hand, by mail ...

The sender then sends the signed data transaction including the signed data to be exchanged to the network with a computer.

A player called "minor" of the network then creates a block called "new block" for convenience using a usual algorithm and a calculator, this new block comprising at least one digital imprint of the last block of the blockchain, said signed data transaction, or even a measure of the amount of work that was required to produce the new block.

This new block is sent according to the arrows F1 in the network for validation according to usual methods by at least one actor. Validation by a predetermined number of actors may be required. For example, the validation of a block may require the validation of the block by at least two actors housed on two different continents.

When the new block is validated by an actor, this actor sends this information according to the arrows F2.

After validation, the new block is inserted in the last position in the block chain.

When the data to be exchanged is of the "first transmission footprint" type and if minors have received the original data in parallel, the process may include a verification phase carried out before building the new block.

Therefore, a minor can consult with a computer program of a computer the blockchain to obtain the public signature key in force of the sender. The miner decrypts the data to be exchanged signed with this public signature key, by applying a usual algorithm for example, to obtain the first transmission fingerprint. At the same time, the miner makes a digital fingerprint known as the "control fingerprint" of the original data with a computer and compares the control fingerprint and the first transmission fingerprint.

If there is a difference (s) between the control print and the first transmission print, the new block is not created, for example.

If the block is created, a user can request the block chain to access the signed data transaction.

Thus, the recipient requests a computer program from a computer to consult the blockchain in order to extract the public signature key in force from the sender, namely the public signature key in force when the the transaction concerned.

The recipient implements a decryption algorithm to decrypt the data to be exchanged signed with this public signature key, in order to obtain the data to be exchanged unsigned.

Optionally, when the data to be exchanged takes the form of the first transmission fingerprint, the unsigned data to be exchanged takes the form of the first transmission fingerprint.

In addition, the recipient can verify the transaction of signed data before using the data concerned.

In fact, the recipient can make a digital fingerprint of the original data received, also known as the "control fingerprint for convenience," and compare the control fingerprint and the first transmission fingerprint.

This recipient also observes the block chain to verify that the block of the block chain containing the signed data transaction has been validated.

Consequently, the recipient ignores the encrypted data transaction if the control fingerprint and the first transmission fingerprint are different and / or if said block of the block chain containing said signed data transaction has not been validated.

For example, if the original data relates to software to be carried on an aircraft, an operator does not install the software.

According to another aspect, the method can make it possible to digitally encrypt data and to transmit them to a so-called "recipient" actor.

A sender can then consult the blockchain with a computer program of a calculator to extract the public encryption key in force assigned to the recipient of the data.

In addition, the sender creates a symmetric key, for example from a usual method and its double encryption keys.

Such a symmetric key is sometimes called the “transfer key”.

The sender then encrypts the data to be exchanged with the symmetric key, using a possibly standard encryption algorithm, which minimizes computation times. In addition, the sender encrypts the symmetric key with the recipient's public encryption key using an encryption algorithm, for example common, to obtain a digitally encrypted symmetric key.

According to an option, a sender can then encrypt original data to obtain the encrypted data to be exchanged.

According to another option, the sender uses a standard algorithm with a calculator to obtain a fingerprint known as the "second emission footprint" of the original data. The sender then encrypts this second transmission fingerprint with the symmetric key to obtain the encrypted data to be exchanged.

The encrypted data to be exchanged is possibly sent by another channel to the recipient.

The encrypted data to be exchanged and the encrypted symmetric key are also sent to the network to record the transaction in the block chain. Such a transaction is said for convenience “transaction of encrypted data”. The encrypted data transaction can thus include the data to be exchanged encrypted with said symmetric key and the symmetric key encrypted with said recipient's public key. The original data can be included in the transaction or transmitted by another channel to a recipient, for example from hand to hand, by mail ...

The sender then sends the encrypted data transaction including the data to be exchanged and the encrypted symmetric key to the network with a computer.

A so-called “minor” actor in the network then creates a so-called “new block”, this new block comprising at least one digital fingerprint of the last block in the block chain, said encrypted data transaction, or even a measurement of a quantity of work that was required to produce the new block.

This new block is sent according to the arrows F1 in the network for validation according to usual methods by at least one actor. When the new block is validated by an actor, this actor sends this information according to the arrows F2. After validation, the new block is inserted in the last position in the block chain.

Thus, the recipient can request the blockchain to access the encrypted data transaction. The recipient implements a decryption algorithm to decrypt the symmetric key contained in the transaction with his private encryption key. Then, the recipient decrypts the encrypted data to be exchanged present in the transaction with said symmetric key.

When the data to be exchanged takes the form of the second transmission fingerprint, the recipient thus obtains the second transmission fingerprint.

In addition, the recipient can make a digital fingerprint of the original data received, also known as the "verification fingerprint" for convenience, and compare the verification fingerprint and the second transmission fingerprint.

This recipient also observes the block chain to verify that the block of the block chain containing the signed data transaction has been validated.

Consequently, the recipient ignores the encrypted data transaction if the verification fingerprint and said second transmission fingerprint are different or if said block of the block chain containing said encrypted data transaction has not been validated.

According to another aspect, the method can include a step of sequestering STP6 keys for each actor. During this stage, an actor creates a copy 90 of his double encryption keys. Consequently, this copy 90 is encrypted using a computer executing stored information and a public key of a double key of a security officer of said actor. The copy thus encrypted is then again encrypted with a public encryption key of a major actor different from said actor having created the copy 90.

Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to identify exhaustively all the possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

In particular, the same block can comprise transactions of various natures. For example, a block may include a data transaction required by one actor and a revocation transaction required by another actor.

Claims (20)

1. Method for sharing data between actors (5) of a network, said method comprising a step of encrypting the data by an asymmetric cryptographic method with double keys, each actor (5) having at least one said double key, characterized in that, a block chain (20) being implemented, a block (25) comprising a digital fingerprint (30) of the block which precedes it in the block chain (20) and at least one transaction (35) which includes data to be shared, at least one block being an initialization block (26) initializing the blockchain and at least one block being a registration block for a new actor, at least one said actor (5) being a major actor, at least one said actor (5) being a subordinate actor and at least one said actor (5) being a computer equipment, a said major actor being authorized to require membership of said network of a new major actor as well as of a subordinate actor born and from new IT equipment, a said subordinate actor being only authorized to require membership of said network of new IT equipment, the method comprises: - an initialization step (STP1) of the block chain which comprises an operation of memorizing said at least one initialization block (26) in the block chain by a predetermined authority using at least one computer , said at least one initialization block (26) comprising at least one said transaction (36) which includes an identity record (84) of a major player, block chain which includes a storage operation - a step of accepting a new actor (STP2) in the at least one block for registering a new actor (29) in the block chain by a said major or subordinate actor using '' at least one computer, said at least one new actor registration block (29) comprising at least one said transaction (34) which includes an identity record (84) of said new actor, a said record of identity (84) of a major player / subordinate or IT equipment comprising data identifying this major player / subordinate player or IT equipment which includes at least one identifier of this major player / subordinate player or IT equipment, a public key of a double key called double signature keys of this major player / subordinate player or IT equipment intended for the signature of data, a public key of a double key called double encryption keys of this major player ur / subordinate actor or IT equipment intended for the signature of data, a public key of a double key called double revocation keys of this major actor / subordinate actor or IT equipment intended for the revocation of at least the double encryption keys and the double signature keys of this major player / subordinate player or IT equipment, said authority no longer intervening at the end of the initialization stage or only intervening during a reinitialization stage of an actor following a revocation of the double revocation keys for this actor. 2. Method according to claim 1, characterized in that a said identity record (84) of a major actor / subordinate actor or computer equipment comprises an identification of a cryptographic signature algorithm associated with said double signature keys of this major player / subordinate player or IT equipment, an identification of a cryptographic encryption algorithm associated with said double encryption keys of this major player / subordinate player or IT equipment, an identification of a cryptographic revocation algorithm associated with said double revocation keys for this major player / subordinate player or IT equipment. 3. Method according to any one of claims 1 to 2, characterized in that a said identity record (84) of a major actor / subordinate actor or IT equipment includes a validity date of said double signature keys of this major player / subordinate player or IT equipment, and a validity date of said double encryption keys for this major player / subordinate player or IT equipment. 4. Method according to any one of claims 1 to 3, characterized in that a said identity record (84) of a major actor / subordinate actor or IT equipment comprises a level of importance of this major actor / subordinate actor or IT equipment used during a validation operation of a block by proof of stake created by this major actor / subordinate actor or IT equipment. 5. Method according to any one of claims 1 to 4, characterized in that said at least one said identifier of a major actor / subordinate actor or IT equipment includes a name of this major actor / subordinate actor or IT equipment or a address of this major player / subordinate player or IT equipment. 6. Method according to any one of claims 1 to 5, characterized in that said identification data of an actor include a level of assurance of this actor making it possible to indicate in which way this actor has been identified. 7. Method according to any one of claims 1 to 6, characterized in that a said identity record (84) of a major actor / subordinate actor or IT equipment comprises a public key of a double key called " double authentication keys ”of this major player / subordinate player or IT equipment intended for the authentication of this major player / subordinate player or IT equipment. 8. Method according to any one of claims 1 to 7, characterized in that said operation of memorizing at least one registration block of a new actor (29) comprises the following operations: - transmission in said network of a request including a said identity record (84) of said new actor, - mining by a said actor of the block chain of a said identification block of a new actor including said identity record (84) of said new actor, - validation of said block by at least one actor in the block chain distinct from the actor having carried out said mining and storage after said validation of said block in the block chain. 9. Method according to any one of claims 1 to 8, characterized in that the method comprises a key modification step (STP3) during which a said actor modifies at least one said double key belonging to him including a valid public key and a private key in force, said modification step comprising the following operations: - generation of a new double key including a new public key and a new private key, - creation and transmission to the network of a transaction called "identification transaction" comprising an identifier of said actor and the public key in force as well as the new public key and a cryptographic algorithm associated with this new public key, said transaction identification comprising said new public key and said identifier digitally signed with the current private key as well as said identifier digitally signed with the new private key, - insertion of said identification transaction in a new block in the block chain. 10. Method according to claim 9, characterized in that said operation of inserting said identification transaction in a new block of the block chain comprises: - a phase of verification of said identification transaction by at least one actor of said network which includes: o a verification that said valid public key belongs to the actor having said identifier by consulting the blockchain with a computer, o a first decryption with a computer and the current public key of said new public key and said digitally signed identifier by the private key in force, o a determination of a first equivalence between said new public key and said identifier obtained by said first decryption and respectively the current public key and the identifier stored in the identification transaction, o a second decryption with a computer and the new public key of said identifier digitally signed by the new private key, o a determination of a second equivalence between said identifier obtained by said second decryption and the identifier stored in the identification transaction, o validation of said identification transaction in p resence of the first equivalence and the second equivalence, - a phase of creating a new block including said identification transaction. 11. Method according to any one of claims 1 to 10, characterized in that the method comprises a revocation step (STP4) during which a said actor revokes at least one said double key belonging to it including a valid public key and a private key in force, said revocation step comprising the following operations: - generation of a new double key including a new public key and a new private key intended to replace the revoked double key including a valid public key and a valid private key, - creation and transmission to the network of a revocation transaction comprising an identifier of said actor and the public revocation key of this actor and the public key in force to be revoked as well as the new public key and a cryptographic algorithm associated with this new key public, said revocation transaction comprising said new public key and said identifier digitally signed with the private revocation key as well as said identifier digitally signed with the new private key, - insertion of said revocation transaction in a new block of the block chain. 12. Method according to claim 11, characterized in that said operation of inserting said revocation transaction in a new block of the block chain comprises: - a phase of verification of said revocation transaction by at least one actor of said network which includes: o a verification that said public revocation key belongs to the actor having said identifier by consulting the blockchain with a computer, o a first decryption with a computer and the public revocation key for said new public key and said digitally signed identifier by the private revocation key, o a determination of a first equivalence between said new public key and said identifier obtained by said first decryption and respectively the current public key and the identifier stored in the revocation transaction, o a second decryption with a computer and the new key public said login sign digitally by the new private key, o a determination of a second equivalence between said identifier obtained by said second decryption and the identifier stored in the revocation transaction, o validation of said new block in the presence of the first equivalence and the second equivalence , - a phase of creation of a new block including said revocation transaction. 13. Method according to any one of claims 1 to 12, characterized in that said method comprises a step of sequestering keys (STP6) which comprises the following operations for a said actor: - creation of a copy of the double encryption keys for this actor, - encryption of the copy with a public key of a double encryption key of a security officer of said actor, then encryption with a public encryption key of a major actor different from said actor. 14. Method according to any one of claims 1 to 13, characterized transaction transaction in that to record in the block chain a so-called "signed data transaction", said signed data comprising data to be exchanged which are digitally signed, the data to be exchanged including original data or a fingerprint digital of the original data known as the “first transmission fingerprint” obtained by a hashing method, the method includes the following operations: - encryption of the data to be exchanged which is to be digitally signed by signing it with the private signature key of a said actor called "sender", to obtain said data to be exchanged which is digitally signed, - sending to the network of the signed data transaction including the data to be exchanged which are digitally signed, - creation of a block called "new block" by a said actor called "minor", said new block comprising at least one digital fingerprint of the last block in the block chain and said signed data transaction, - validation of the new block by at least one said actor, - insertion of the new block in the block chain after said validation. 15. The method of claim 14, characterized in that, the data to be exchanged taking the form of a said first emission imprint, said miner having received said original data, the method comprises a verification operation carried out before constructing the new block including the operations of: - consultation of said blockchain to obtain the public signature key in force of the sender, - decryption, with the sender's public signature key in force, of the data to be exchanged which is digitally signed to obtain the said first transmission fingerprint, - creation of a digital fingerprint known as the "control fingerprint" of the original data, - comparison of the control fingerprint and said first transmission fingerprint. 16. Method according to claim 15, characterized in that, the data to be exchanged taking the form of a so-called first transmission imprint, a recipient performs the following operations: - verification of said signed data transaction: o by consulting said blockchain to obtain the public signature key in force from the sender, o by decrypting, with the public signature key in force from the sender, the data to be exchanged which are digitally signed to obtain said first transmission fingerprint, o by making a digital fingerprint known as the “control fingerprint” of the original data, o by comparing the control fingerprint and said first transmission fingerprint, - verification that the block of the block chain containing said signed data transaction has been validated, - disregarding said signed data transaction if the control fingerprint and said first transmission fingerprint are different or if said block of the block chain containing said signed data transaction has not been validated. 17. Method according to any one of claims 1 to 16, characterized in that in order to record in the block chain a transaction called "encrypted data transaction", said encrypted data transaction comprising data to be exchanged which are digitally encrypted, the data to be exchanged including original data or a digital fingerprint of the original data known as the “second transmission fingerprint” obtained by a hash method, the encrypted data transaction being intended for a said actor called “recipient”, the method comprises the following operations: - consulting the blockchain to obtain the current public encryption key assigned to the recipient, - creation of a symmetric key and encryption of the data to be exchanged with this symmetric key to obtain data to be exchanged digitally encrypted with said symmetric key, encryption of the symmetric key using the recipient's public encryption key to obtain a symmetric key digitally encrypted with said public key, sending the encrypted data transaction to the network, said encrypted data transaction including said digitally encrypted exchange data with said key symmetrical and said digitally encrypted symmetric key with said recipient's public key, - creation of a block called "new block" by an actor said "Minor", said new block comprising at least one footprint of the last block in the blockchain, said block transaction encrypted data, - validation of the new block by at least one actor, - insertion of the new block in the block chain. 18. The method as claimed in claim 17, characterized in that, the data to be exchanged taking the form of the second transmission fingerprint, a recipient having received the original data, said method comprises the following operations: - verification of said encrypted data transaction by: o decryption using the private encryption key in force of the recipient of the symmetric key encrypted with said public encryption key of the recipient, o decryption using said symmetric key of the data to be exchanged encrypted with said symmetric key to obtain the second fingerprint transmission, o production of a digital fingerprint known as the "verification fingerprint" of the original data, o comparison of the verification fingerprint and said second transmission fingerprint, 5 - not taking into account said encrypted data transaction if the verification fingerprint and said second transmission fingerprint are different. 19. Method according to any one of claims 14 to 18, characterized in that at least one data transaction 10 includes the identity of the sender or a registration number or a date. 20. Data exchange system (1), characterized in that said data exchange system (1) comprises for each actor (5) of the network (2) at least one computer (10) for implementing said method according to any one of claims 1 to 19, at least one computer of at least one actor (5) memorizing said block chain.