WO2018121797A1

WO2018121797A1 - Trust network-based decentralized public key management method and management system

Info

Publication number: WO2018121797A1
Application number: PCT/CN2018/074647
Authority: WO
Inventors: 朱岩
Original assignee: 北京科技大学
Priority date: 2016-12-26
Filing date: 2018-01-31
Publication date: 2018-07-05
Also published as: CN107070644A; CN107070644B

Abstract

The present invention primarily relates to the field of information security technology, and specifically relates to a novel decentralized public key management method and trust model, the method being constructed on a distributed data network platform like blockchain or P2P, ensuring each node of the platform is capable of participating in maintaining full life cycle management of a user public key, and recording a every status change in a user public key during a life cycle in ledger form. The present method can add public key records which have passed verification to a consistent public key storage structure of a platform to be saved; all public key records of the same user may be arranged from first to last in order of time to generate a public key log chain, and an authentication chain and a trust network may be formed based on a recommender signature; efficient public key search may be implemented based on a user identifier. The present invention ensures convenient and accurate issuance and acquisition of a user public key, ensures an acquired public key is valid, correct, consistent, and not deceptive, and can act as infrastructure to support authentication, encryption, integrity and accountability services.

Description

Decentralized public key management method and management system based on trust network

Technical field

The invention mainly belongs to the field of information security technology, and particularly relates to a decentralized public key management method and management system based on a trust network.

Background technique

In recent years, with the wide application of new technologies such as mobile smart devices and cloud computing, people are communicating more and more through the Internet. E-commerce and online transactions are becoming more and more popular, and human beings are moving towards the digital society. In order to protect the data confidentiality, integrity, usability and authenticity of various network activities in the digital society, various modern cryptography technologies have been widely adopted, especially public key cryptography, which has become the core of security for the Internet and the entire digital society. Compared with traditional symmetric cryptography, public key cryptography not only enables data encryption and message authentication, but also implements functions such as user identity authentication, digital signature, secure computing, key exchange, and verifiable secret sharing to ensure new Internet services. Development has laid a solid foundation for security.

The existing public key cryptography technology is built on PKI (Public Key Infrastructure), which is an infrastructure that supports public key management and provides "public key certificate" issuance and authentication services. Users can use the PKI platform to provide The security services implement and develop a variety of security features and applications based on public key cryptography. It can be said that the PKI framework has become the foundation and credibility of the modern Internet. However, the existing PKI architecture is dominated by government and companies. PKI-based public key management is far from being popularized on the Internet. At the general user level, PKI is rarely accepted, limiting the general public's need for privacy protection and other security services. The reasons why the PKI architecture cannot be popularized are: 1) the user's real-name authentication completes the issuance of the public key certificate, violating the principle of Internet anonymity; 2) the charging cost is too high for the general public; 3) the storage and retrieval service of the certificate is not provided. Another public key management technology is the PGP (Perfect Privacy) architecture, which is a technology that is spontaneously formed by users on the Internet and exchanges public keys between friends that users are familiar with or trust. Also because the organization is loose, it is not widely used.

Summary of the invention

In view of the above problems, the present invention provides a decentralized public key management method and management system based on a trust network. The public key management method can support infrastructure for authentication, encryption, integrity, and accountability services.

The invention is achieved by the following technical solutions:

A decentralized public key management method, wherein the decentralized public key management method adds all verified public key records to a consistent public key storage structure in a decentralized network platform for storage;

For all public key records under the same user ID in the public key storage structure, the method can generate a public key log chain, and the public key log chain can sequentially access the same user in order from back to front in time. Identify all relevant public key records;

The method can form an authentication chain based on the recommender signature in the public key record, the authentication chain can form a trust network, the trust network can record the delivery process of the recommendation relationship and realize the transmission of the trust relationship.

The consistent public key storage structure refers to that all nodes in the decentralized network platform participate in maintaining and storing the same user public key record set. The structure of the public key record includes the following structure:

1) Status information: including a forward pointer pointing to the previous public key record, the forward pointer is used to generate a public key log chain in chronological order and record the change of the public key record state; The forward pointer refers to the location information of the previous log of the record in the system, and may be the record address information or the hash value of the record;

2) Public key information: used to store related information of the user's public key; including public key length and cryptographic parameter list;

3) Certificate information: used to store information related to the use of the user's public key; including: certificate version, serial number, owner, expiration date; the owner information of the certificate information may be signed or claimed by any name, but must be Guarantee the full platform uniqueness of the signature or logo. The method of signature or identification includes real name, pseudonym, email address, website address, uniform resource locator URL, and so on.

The signature or logo pseudonym method used can implement the user's "anonymity". The implementation method includes using the hash name of the user's real name as the owner's signature or identification ID to ensure uniqueness. The unidirectionality of the Hash function guarantees the known signature. Unable to guess the real name.

4) signature list: for storing a digital signature of the above three aspects of information by the recommender or the public key owner, the signature list including at least one digital signature, each digital signature containing a pointer to the signer's public key record; signature The list can also include the signature type and signature;

Each digital signature can be used as a recommendation for a different referrer. A pointer to the signer's public key record is stored in each signature, so that the pointer can be used to obtain the recommender's public key, and the public key is used to verify the validity of the signature. If the verification is passed, it indicates that the recommendation is valid; otherwise it indicates that the recommendation is invalid and the signed information is not trusted. The security of this type of recommendation comes from the unforgeability of the signature.

The public key record can record public key certificates used by various public key cryptosystems, and the public key certificates include: X.509, PKI certificate, PGP certificate, and self-certificate. The public key certificate includes public key information, certificate information, and a list of signatures. The self-certificate refers to a certificate formed by the public key record owner calculating the signature by using the public key in the record.

The generation of the public key log chain includes the following steps:

1) Public key record verification: each node in the centralized network platform verifies the public key record submitted by the user;

2) generating a public key log chain: storing the verified public key record in a consistent storage structure of the decentralized network platform; generating a public key log chain according to the forward pointer in the status information, the public key log The chain can access all public key records associated with the public key in order from the head node in order from time to time. The owner of the public key log chain uses an arbitrary and unique character string as a user identifier, and the user identifier can use the hash value of the user's real name as a pseudonym to implement user anonymity.

The change of the public key record status refers to a protocol executed by changing the public key record status, and the protocol includes: a registration protocol, an update protocol, and a revocation protocol.

The registration protocol is used for authenticity verification of a public key record of a user and generation of a public key log chain; the registration protocol includes the following process:

1) Trust request phase: the public key owner generates a public key record and sends a trust request;

2) Public key verification phase: each node of the network platform verifies the public key credibility;

3) Signature collection phase: The public key owner collects the list of recommenders' signatures and sends a registration request;

4) Record generation phase: each node of the network platform verifies the signature in the registration request, and writes the public key record into the public key storage structure after passing the verification;

5) Log chain generation phase: Each node of the network platform establishes a head node of the public key log chain in the lookup table, and links the aforementioned public key record to the head node of the public key log chain.

In step 2), the verification of the validity of the public key by each node of the network platform is a validity verification process of the public key owner credibility verification and the held public key. Public key owner credibility verification can be verified by trust metrics such as friend relationship, trust relationship, trust calculation model, etc. The public key validity verification process includes encrypting the secret by public key and sending it to the public key holder for decryption and return. The way to verify in a secret way.

The update protocol is mainly used for user password update and upgrade, that is, replacing the old key with a new one. If the certificate has expired, it can be upgraded within the specified time without re-registration. The update protocol includes the following process:

1) Update request phase: the public key owner generates an updated public key record, and signs the update public key record with the old private key and sends an update request;

2) Record generation phase: each node of the network platform verifies the validity of the signature in the updated public key record by using the old public key in the public key log chain, and records the new public key after passing the verification;

3) Log chain change phase: Each node of the network platform links the updated public key log to the head node of the public key log chain in the public key lookup table.

The revocation agreement is used by the public key owner to initiate an application to revoke and discard the public key certificate. After the public key is revoked, it cannot be activated and reused, and can only be re-registered to apply for a new certificate. The revocation agreement includes the following process:

1) The revocation request phase: the public key owner generates the revocation public key record and signs the revocation public key record with the private key and sends the revocation request;

2) Record generation phase: each node of the network platform verifies the validity of the signature in the revoked public key record by using the public key in the public key log chain, and records the revoked public key record after passing the verification;

3) Log chain change phase: Each node of the network platform links the undo public key log to the head node of the public key log chain in the public key lookup table.

The generation of the authentication chain based on the trust network is specifically as follows:

Each public key record signature list stores at least one recommender signature, and each of the recommender signatures is a recommendation certificate of the recommender, and each recommender signature stores a signer public key record pointer, according to the signer The public key record pointer can form an authentication chain.

The authentication chain can form a trust network, and the trust relationship supported by the trust network includes direct trust, hierarchical trust, and indirect trust relationship. The method for obtaining the trust relationship includes: negotiating trust by members in the decentralized network platform, and issuing the certificate according to a third-party trusted certificate authority (such as a PKI certificate authority CA).

The method is also capable of retrieving a user's public key based on the user identification in the public key record.

The retrieval of the user public key depends on a public key retrieval structure, which is composed of a lookup table and a list of head nodes of the public key log chain; the lookup table uses the user identifier of the public key owner as a search key. The methods for constructing the lookup table include: a hash lookup table, a binary search tree, a B tree, a B+ tree, and a lexicographic index table.

The user ID is retrieved based on the user identifier in the public key record, specifically:

1) Retrieval request phase: the requester generates and sends a query request according to the user ID of the public key to be queried;

2) Lookup table retrieval stage: each node of the network platform relies on the keyword retrieval method of the lookup table to find the item corresponding to the user identifier, and extracts the head node of the public key log chain from the item;

3) Log chain search phase: Each node of the network platform searches in order from the head node of the public key log chain to obtain the most recent valid public key record, and performs the trustworthiness of the public key record obtained by the search according to the public key trust model. Metric, output the public key record and the credibility measurement result;

4) Consistency check phase: The requester receives a specified number of public key records and credibility measurement results, and compares the received query results; if they are consistent, determines the availability of the public key and returns the public key. ; otherwise, it returns "failed".

The credibility of the public key in the public key record can be measured by the public key log chain and the record information in the authentication chain. According to the metric, the public key credibility can be divided into different trust levels, and the trust level includes: fully trusted The edge is credible, effective but not credible and invalid.

The public key trust model in step 3) is an algorithm or function, algorithm or function for measuring the credibility of the public key record according to the recommender list, the public key validity period, and the public key state change information in the public key record. The output is a credibility metric; the determining the availability of the public key refers to whether the public key record can be used depending on whether the credibility metric is greater than or equal to the security requirement of the public key operation. For example, the credibility measure of the public key record is edge trusted, the security requirement of the public key operation is completely trusted, and the edge trust is less than fully trusted, then the public key record will not be suitable for use.

A decentralized public key management system based on trust network.

The public key management system includes a decentralized network platform and a consistent public key storage structure with network-wide consistency. The centralized network platform is constructed by a distributed data system, including: a blockchain network, a P2P network, and a distribution. a database system, a multi-party secure computing system; the consistent public key storage structure is configured to store a public key record that is verified.

In this decentralized network, there is a peer relationship between nodes, no central node, and each node has a network-consistent consistent storage structure, which is used for "billing" The form records the various state changes of the public key of the user (including individuals, companies, enterprises, etc.) in the life cycle, wherein the public key life cycle includes the whole process of generating, publishing, updating, and canceling the public key. Here, "consistency" means that all nodes in the network platform will participate in the maintenance of the user's public key's full lifecycle management, and establish a reliable correspondence between the identity and the public key through the consensus mechanism of the large-scale node, the public key storage structure It is also multi-copy, but maintains the consistency, integrity, and non-changeability of data between multiple copies.

The consistent public key storage structure of the present invention is used to store information of a user's public key and record state changes in chronological order, and is called "public key record", "public key log" or "public key certificate". The public key record is submitted by the public key owner (or holder) to the system, and after being verified by the system, it is added to the decentralized network platform for storage.

Advantageous technical effects of the present invention

The method of the invention enables a user in the network to efficiently, conveniently and accurately verify, query and obtain the public key of a certain user (represented by an identity), and at the same time ensure the validity, correctness and consistency of the obtained public key. Not deceptive. At the same time, the security risk of public key management lies in how to guarantee the credibility of the public key. Since the information obtained in the Internet is not reliable, the present invention guarantees the credibility and authenticity of the public key certificate.

The method has the following characteristics:

1) Decentralized management using a centralized network platform, capable of supporting any number of certificate institutions or users to participate in certificate management;

2) Forming an authentication chain supporting the trust network, and performing credibility verification on the public key record obtained by the user;

3) Provide fast search and storage and access services for the user's public key;

4) Public key record, supporting public key life cycle management in the form of time bookkeeping;

5) Public key log chain, providing integrity and accountability services for public key certificates;

6) Identifying anonymity, allowing users to anonymously issue and obtain public key certificates;

7) Compatible with existing PKI and PGP architectures, with good scalability and strong security.

The invention has wide application value, including a secure, reliable and efficient key management solution for any public key cryptosystem, including identity authentication, key exchange, encryption, signature, secure computing and other security services, and Meeting the key management needs of the government, enterprises, military, schools, hospitals and other large-scale user groups will drive the development of the entire Internet security industry in China and promote the establishment of a more secure and reliable Internet trust mechanism.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a system configuration diagram of a public key management framework in the present invention.

2 is a flow chart showing the execution of a registration protocol in the present invention.

Figure 3 is a flow chart showing the execution of an update protocol in the present invention.

Figure 4 is a flow chart showing the execution of the revocation protocol in the present invention.

Figure 5 is a flow chart showing the execution of the public key retrieval protocol in the present invention.

Figure 6 is a block diagram of an information storage structure based on a blockchain in the present invention.

detailed description

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Rather, the invention is to cover any alternatives, modifications, and equivalents and embodiments of the invention. Further, in order to provide a better understanding of the present invention, the specific details are described in detail in the detailed description of the invention. The invention may be fully understood by those skilled in the art without a description of these details.

Example 1

1) Decentralized platform construction

This embodiment is constructed on the basis of a blockchain system. As shown in FIG. 6, the blockchain network includes the following entities:

1 system member P:={P ₁ ,..., P _n }: each member P _i is an independent execution node of the system and stores a copy of the blockchain BC;

2 distributed network net: a P2P network that ensures that members in the system are connected to each other;

3-block storage structure BC:={B ₁ ,...,B _n }: The blockchain is a distributed storage structure composed of a number of data blocks B _i , each data block B _i :={hdr _i ,body _i } It consists of a "block header hdr _i " and a "data store body _i " containing a certain number of data records;

4 Consensus Agreement: An agreement to ensure that all members of the blockchain system collaborate and obtain common results, such as mining mechanisms, and the agreement of the Byzantine.

Given the hash function Hash: {0,1}*→{0,1}l, the data structures used in the block storage structure include:

1 block header hash table HTable: a singly linked list used to organize all block headers {B ₁ ,...,B _n }, the list pointer ptr=Hash(B _i ) is the hash function value of the previous block data, ie B _i+1 :={ptr,block_info,...,root};

2 Record Hash Tree HTree: A binary tree used to organize all data records {cert ₁ ,...,cert _m } in the data store body _k . The leaf node is the hash value Hress(cert _i ) of the data record cert _i The tree node node _i stores the Hash function value of the subordinate node (node _2i , node _2i+1 ), that is, node _i =Hash(node _2i , node _2i+1 ), and the root node root=node _{1 is} stored in the area. Block head B _k .

All records {cert _i } in this blockchain are stored in the relational database system and searched with Hash(cert _i ) as the key or pointer address.

2) Public key record structure

In this embodiment, as shown in FIG. 6, information for storing a user public key pk in each data record cert _i is called a public key record or a public key certificate. The public key record structure is defined as follows:

1 state information state_info: = { forward pointer forward_ptr, operation type op_type, etc.};

2 public key information pk_info: = {public key length pk_length, type pk_type, parameter list para_list, etc.};

3 certificate information cert_info: = {certificate version version, serial number serial_num, owner's user ID holderID, expiration date POV, etc.};

4 signature information sig_info: = {list size size, number of signatures sig_num, signature record table sig_list, etc.}; wherein the signature record table sig_list: = {recommended pointer Intro_ptr, signature type sig_type, signature sig, etc.}.

In the above definition, the state information before the state_info is used to store this public key pointer forward_ptr cert _i recording address information in a block chain, the previous record of this public key (e.g., cert _j), i.e., a public key record chain (See below) The hash pointer of the previous block, namely forward_ptr=Hash(cert _j ). The public key information pk_info and the certificate information cert_info in the public key record are consistent with the two parts of the common X.509 or PGP public key digital certificate.

The signature information sig_info is used to store a digital signature for data including the block information state_info, the public key information pk_info, and the certificate information cert_info. However, unlike the usual X.509 public key digital certificate, the signature list sig_list can store multiple signatures, and in some cases can also store "self-signed", that is, the public key certificate is performed with the certificate holder's private key. signature.

In order to achieve user anonymity, the owner's user ID holderID may be the hash value of the owner's real identity, ie holderID=Hash(holderID).

3) Public key retrieval structure

The public key lookup table is constructed by a Hash lookup table, which enables the retrieval of public key certificates. As shown in Figure 1, the Hash lookup table is defined as follows:

1, cryptography collision free Hash function HashMap: {0, 1} ^* → [0, m-1], used to convert the owner "identifier holderID" into the address in the random Hash lookup table t←HashMap(holderID);

2. A pointer array A[0:m-1] of length m, each array unit storing a pointer of the "collision linked list", that is, A[i]=Link _i for storing in the form of "collision linked list Link _i " a list of public key records corresponding to each hash value, if a certain matrix unit has no corresponding record, then store NULL;

3. The collision list Link _{i is} used to store a linked list of all public key records mapped to the unit A[i], and each item in the list contains a "public key certificate chain" header node link _i,j := {ID,active,ptr}, where, if link _t,j .ID=holderID, then the pointer link _i,j .ptr stores the first record storing the public key record chain Cert_Link _i,j in the blockchain The cert address Hash(cert) (ie link _{i, j} .ptr=Hash(cert)) and the basic information of the public key record chain.

4. The public key log chain Cert_Link _i,j :={link _i,j ,cert ₁ ,...,cert _t } records the usage record of the public key identifier holderID, where the link header is link _i,j .

a) The first one is cert _1, by link _{i, j} hash address pointer _{link i, j .ptr = Hash (} cert 1) find the record;

b) The second recording is cert _2, cert by the hash address pointer _{cert. 1} _{1 .forward_ptr} = Hash (cert ₂₎ to locate the record;

c) repeat the above process, the kth record is cert _k , which can be found by the cert _k-1 hash pointer cert _k-1 .forward_ptr=Hash(cert _k );

d) The process is up to the last record, its forward pointer is empty, ie cert _t .forward_ptr=NULL.

It can be seen that the public key certificate chain Cert_Link _i,j :={link _i,j ,cert ₁ ,...,cert _t } is started by a node link _{i,j in the} link list Link _i , and is recorded by the public key certificate. The "forward pointer forward_ptr" constitutes a public key record singly linked list, and the public key certificate chain records all the information of the public key certificate.

4) Public key retrieval protocol based on user identification (as shown in Figure 5):

Step 1: Retrieve the request phase

The requester A generates and sends a query request according to the identifier reqID of the public key to be queried;

Step 2: Hash search phase

Network platform each node (including the local node) computing t ← HashMap (reqID), the lookup table extraction items Link in _{Hash t ← A [t] =} A [HashMap (reqID)] corresponding to the "collision list" Link _t: = {link _{In t,1} ,...,link _t,k }, link _t,j .ID=reqID is compared item by item. If the jth entry is true, the link _t,j is extracted, which is the head node of the "public key log chain" Cert_Link _t,j ; otherwise, it returns "failure".

Step 3: Log chain search phase

Find each public key record in turn from the header node link _{t,j of the} "public key log chain" Cert_Link _t,j :={link _t,j ,cert ₁ ,...,cert _m } to get the nearest valid public key. Record cert _k and trust the model according to the public key, for example using the formula

Trust=(cert _k .sig_num+m)·left(cert _k .POV)

Where cert _k .sig_num indicates the number of recommender signatures in the public key record, m indicates the length of the public key log chain, left(cert _k .POV) indicates the remaining validity period length, and trust(cert _k ) trust metric value is four categories. : Fully trusted L3, edge trusted L2, valid but not trusted L1, invalid return trust metric L0. Finally, the public key record and trust metric (cert, trust(cert _k )) are output.

Step 4: Consistency Check Phase

After the requester A receives the specified number (such as at least 5) of the platform query return result {(cert, trust(cert _k ))}, the requester A compares the results. If they are consistent, the availability of the public key is determined according to the trust metric trust(cert _k ), and the public key cert.pk_info is returned; otherwise, "failed" is returned.

For example, the security requirement for public key operation is L2. If trust(cert _k )=L3>L2, the public key is available. Conversely, if trust(cert _k )=L1<L2, the public key is unavailable. It should be noted that even if the public key is not available by the above method, the user can finally decide whether to use the public key.

4) Three operating protocols (as shown in Figures 2, 3, 4)

The public key record cert operation type refers to the type of protocol executed by this record, including: registration protocol Protocol_Regist, update protocol Protocol_Update, and revocation protocol Protocol_Revoke.

The three main protocols are described below:

1 registration agreement Protocol_Regist (as shown in Figure 2):

In the first step, the registered user A (identified as holderID) generates a public/private key pair (pk _A , sk _A ), and generates a “certificate registration request” cert _A for pk _A according to the certificate record cert format, and passes the blockchain. The network net is sent to all system members in the form of a "trust request";

The second step, each block chain network members P _k (referred to as referees) to select the "Trust request" public key pk _A for authentication, if authentication is successful, P _k with its own private key sk _k Signing sig _k =sign(sk _k , cert _A ), and returning the signature sig _k and the personal public key record pointer as the recommender pointer Intro_ptr _k to the registration applicant A;

The authentication method here is: the recommender P _k sends a public key pk _A using the registrant to encrypt the secret message m to obtain c=Encrypt(pk _A , m), and sends it to the registration applicant's mailbox, and the registration applicant A uses the private key sk _A decrypts the secret information m=decrypt(sk _A , c) and passes the information m back to the recommender P _k .

In the third step, the registration applicant A puts the signature {sig _k } into the public key certificate cert after collecting enough {sig _k } of the recommender (for example, setting up enough for at least 5 signatures). _A 's signature list sig_list is used as a trust basis and is again submitted to the blockchain network in the form of a "registration request";

A fourth step, the block chain network (each node) is recommended by the author's public key certificate cert _A signature review {sig _k}, i.e. one by one with the signature sig _k Intro_ptr _k points to authenticate the public key pk _k And according to the "block generation method", it is added to cert _A to the current block B _i of the blockchain for storage.

In the fifth step, the Hash index value t is calculated according to t←Hash(holderID) in the Hash lookup table, and the collision list Link _t ←A[t] pointed out by the tth item A[t] in the pointer array A, and Link _t :={link _t,1 ,...,link _t,k }; verify ID _t , _j =holderID one by one according to the linked list pointers ptr _t,1 ,...,ptr _t,k , if there is no identical item, add new A link and use it as the head node of the public key certificate chain Link _t :={link,link _t,1 ,...,link _t,k }, and point the forward pointer in the node to the newly generated area of the previous step. The block, link.ptr=Hash(cert _A ), constructs the public key certificate chain Cert_Link _t .

In the above protocol, the trust structure refers to a public key trust relationship formed by a "recommendation relationship" composed of a plurality of recommenders _Pk signatures when a public key is registered in the blockchain. This kind of trust relationship is transitive, that is, subject A learns from the trust of subject B to subject C, and forms an indirect trust relationship between subjects A and C.

2 update the protocol Protocol_Update (as shown in Figure 3):

In the first step, the public/private key pair of public key owner A is (pk _A , sk _A ), which generates a new public/private key pair (pk' _A , sk' _A ) and uses the public key. the new public key certificate format pk _'a encapsulated obtained cert' _a, of cert _'a sign sig' _a with the old private key sk _a, and sends it to "update request" block chains to form a network;

In the second step, the blockchain network (in each node) reviews the submitted public key certificate cert' _A , that is, the signature sig' _A is verified by the old public key pk _A in the replaced block, and the approval is followed by The block building method adds cert' _A to the current block of the blockchain for storage.

In the third step, each node of the network platform adds a new record cert' _A to the "public key log chain" header node in the public key lookup table. The process is as follows: in the Hash lookup table, the Hash index value t is calculated according to t←Hash(holderID), and the collision list Link _t ←A[t] pointed out by the tth item A[t] in the pointer array A, and Link _t :={link _t,1 ,...,link _t,k }; verify ID _t,j =holderID one by one according to the linked list pointers ptr _t,1 ,...,ptr _t,k until the first match link _{t is found, k: = {ID, active,} ptr}, assigning the hash pointer to the new record ptr cert 'cert _a forward pointer _{_{of' a .forward_ptr = link t, k}} .ptr, and then change the link _{t, k} .ptr = Hash(cert' _A ), thereby adding the new record cert' _A to the "public key log chain" Cert_Link _t,k :={link _t,k ,cert' _A , cert ₁ ,...,cert _t }.

3 Cancel the protocol Protocol_Revoke (as shown in Figure 4):

In the first step, the public key owner A fills in an empty certificate cert _A and fills in the operation type as "undo", then the private key sk _A is signed to sign the empty certificate sig _A , and it is in the form of "revoked request" Sent to the blockchain network;

In the second step, the blockchain network (in each node) reviews the submitted public key certificate cert _A , that is, the public key pk _A in the forward block authenticates the signature sig _A. If the audit is passed, cert _{A is} added to the current block of the blockchain for storage according to the block building method.

In the third step, each node of the network platform adds the revocation record cert _A to the "public key log chain" header node in the public key lookup table, and the process is the third step of the Protocol_Update protocol.

5) The overall structure of the system (as shown in Figure 1)

Combining the various structures and protocols in the above-described decentralized public key management method based on the trust network, a decentralized public key management system based on the trust network can be constructed. The system is shown in FIG. 1 . The system is described as follows:

1) The decentralized storage structure uses a blockchain network. Figure 1 depicts a blockchain consisting of six blocks BC={B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B ₆ } A structure in which each block includes B _i :={hdr _i , body _i }. The six block headers are {hdr ₁ , hdr ₂ , hdr ₃ , hdr ₄ , hdr ₅ , hdr ₆ }, respectively, which form a block head list through the block chain pointer.

2) corresponding to the data store of each block body B _i _i, Figure 1 shows a body comprising a public key CERT _i, _i recorded in the data store. For convenience, we name each public key record by public key name PK _A (representing user A's public key) and operation type (Regist registration, Update update, Revoke revocation).

3) The right side of Figure 1 shows a public key log chain lookup table consisting of a hash lookup table. As described in the above 3) public key retrieval structure, the lookup table is composed of a hash map HashMap, m pointer arrays A[0:m-1], and three collision list tables Link _i .

4) Public key log chain construction: The head node of the public key log chain is stored in each node of the collision list Link _i in the hash lookup table, and is linked into a singly linked list by the forward_ptr in each public key record. As shown in Figure 1, for user A's public key lookup, user A's public key log chain node is first obtained by link _m-3,1 ←A[HashMap(A)], and then user A's is obtained along the chain pointer. Public key log chain

Cert_Link _A :={link _m-3,1 , PK _A (Revoke), PK _A (Upate), PK _A (Regist)}.

Through the above public key log chain, the public key goes through the process from registration to update and finally to logout.

5) Trust network: The recommender or owner signature Sig _i in the cert _i is recorded by the public key to constitute the trust transfer relationship and network of the public key. As shown in Figure 1, when the public key of user A is registered, there are signatures Sig _R1 and Sig _{R2 of} two recommenders (users R1 and R2 respectively); continue to query the public key records of the two recommenders, and they know that they have one common The recommender R signed them Sig _R and Sig _R' . According to the above relationship, a trust network is constructed: R←R1←A and R←R2←A, where ← represents a trust relationship, that is, R←R1 indicates that the credibility of R1 is derived from R. According to the above trust relationship, a more complex trust network can be constructed.

Claims

A decentralized public key management method based on a trust network, characterized in that the decentralized public key management method adds all verified public key records to a consistent public key storage structure in a decentralized network platform Save in

For all public key records under the same user ID in the public key storage structure, the method can generate a public key log chain, and the public key log chain can sequentially access the same user in order from back to front in time. Identify all relevant public key records;

The method can form an authentication chain based on the recommender signature in the public key record, the authentication chain can form a trust network, the trust network can record the delivery process of the recommendation relationship and realize the transmission of the trust relationship.
The method for decentralized public key management based on a trust network according to claim 1, wherein the decentralized network platform is constructed by a distributed data system, including: a blockchain network, a P2P network, and a distribution. Database system, multi-party secure computing system.
The trust network-based decentralized public key management method according to claim 1, wherein the consistent public key storage structure refers to that all nodes in the decentralized network platform participate in maintenance and storage in the same manner. User public key record set, the public key record includes:

1) Status information: including a forward pointer for pointing to the previous public key record, the forward pointer is used to generate a public key log chain in chronological order and record the change of the public key record state;

2) Public key information: used to store related information of the user's public key;

3) Certificate information: used to store information related to the use of the user's public key;

4) Signature list: used to store the digital signature of the above three aspects of information by the recommender or the public key owner. The signature list includes at least one digital signature, and each digital signature includes a pointer to the signer's public key record.
The trust network-based decentralized public key management method according to claim 3, wherein the public key record is capable of recording a public key certificate used by various public key cryptosystems, and the public key certificate Including: X.509, PKI certificate, PGP certificate, self-certificate.
The trust network-based decentralized public key management method according to claim 1, wherein the trust relationship supported by the trust network comprises a direct trust, a hierarchical trust, and an indirect trust relationship.
The trust network-based decentralized public key management method according to claim 5, wherein the trust relationship obtaining method comprises: a member negotiation by a decentralized network platform, and a third-party trusted authentication mechanism Issued.
The method for decentralized public key management based on a trust network according to claim 1, wherein the credibility of the public key in the public key record can be measured by the record information in the public key log chain and the authentication chain. According to the metric, the public key credibility can be divided into different credibility levels, and the credibility level includes: completely credible, edge trusted, valid but not trusted, invalid.
The method for decentralized public key management based on a trust network according to claim 1, wherein the generating of the public key log chain comprises the following steps:

1) Public key record verification: each node in the centralized network platform verifies the public key record submitted by the user;

2) generating a public key log chain: storing the verified public key record in a consistent storage structure of the decentralized network platform; generating a public key log chain according to the forward pointer in the status information, the public key log The chain can access all public key records associated with the public key in order from the head node in order from time to time.
The trust network-based decentralized public key management method according to claim 1, wherein the owner of the public key log chain uses an arbitrary and unique character string as a user identifier, and the user identifier can be a user. The hash value of the real name is used as a pseudonym to implement user anonymity.
The trust network-based decentralized public key management method according to claim 1, wherein the authentication chain generation method is: storing at least one recommender signature in each public key record signature list, each of which The recommender signature is a recommendation certificate of the recommender, and each poster signature holds a signer public key record pointer, and the signer public key record pointer can form an authentication chain.
The method for decentralized public key management based on a trust network according to claim 1, wherein the method is further capable of realizing retrieval of a user's public key based on a user identifier in the public key record.
The trust network-based decentralized public key management method according to claim 11, wherein the retrieval of the user public key is dependent on a public key retrieval structure, and the public key retrieval structure is composed of a lookup table and The head node list of the public key log chain is composed; the lookup table uses the user ID of the public key owner as a search key, and the method for constructing the lookup table includes: a hash lookup table, a binary search tree, a B tree, a B+ tree, and a lexicographical order. direction chart.
The trust network-based decentralized public key management method according to claim 12, wherein the public key retrieval structure can implement fast user public key retrieval based on the user identifier, specifically:

1) Retrieval request phase: the requester generates and sends a query request according to the user ID of the public key to be queried;

2) Lookup table retrieval stage: each node of the network platform relies on the keyword retrieval method of the lookup table to find the item corresponding to the user identifier, and extracts the head node of the public key log chain from the item;

3) Log chain search phase: Each node of the network platform searches in order from the head node of the public key log chain to obtain the most recent valid public key record, and performs the trustworthiness of the public key record obtained by the search according to the public key trust model. Metric, output the public key record and the credibility measurement result;

4) Consistency check phase: The requester receives a specified number of public key records and credibility measurement results, and compares the received query results; if they are consistent, determines the availability of the public key and returns the public key. ; otherwise, it returns "failed".
The trust network-based decentralized public key management method according to claim 13, wherein the public key trust model is based on a list of recommenders, a public key validity period, and a public key status in the public key record. The change information measures the credibility of the public key record, and the output is a credibility measure; the determining the availability of the public key refers to whether the credibility measure is greater than or equal to the security requirement of the public key operation, and returns the public key record. Can it be used?
The de-centralized public key management method based on the trust network according to claim 3, wherein the change of the public key recording state refers to a protocol executed by changing the public key recording state, and the protocol includes: Registration agreement, update agreement, cancellation agreement.
The trust network-based decentralized public key management method according to claim 15, wherein the registration protocol is used for credibility verification and public key log chain generation of user public key records; The agreement includes the following process:

1) Trust request phase: the public key owner generates a public key record and sends a trust request;

2) Public key verification phase: each node of the network platform verifies the public key credibility;

3) Signature collection phase: The public key owner collects the list of recommenders' signatures and sends a registration request;

4) Record generation phase: each node of the network platform verifies the signature in the registration request, and writes the public key record into the public key storage structure after passing the verification;

5) Log chain generation phase: Each node of the network platform establishes a head node of the public key log chain in the lookup table, and links the aforementioned public key record to the head node of the public key log chain.
The trust network-based decentralized public key management method according to claim 15, wherein the update protocol is used for user password update and upgrade; and the update protocol includes the following process:

1) Update request phase: the public key owner generates an updated public key record, and signs the update public key record with the old private key and sends an update request;

2) Record generation phase: each node of the network platform verifies the validity of the signature in the updated public key record by using the old public key in the public key log chain, and records the new public key after passing the verification;

3) Log chain change phase: Each node of the network platform links the updated public key log to the head node of the public key log chain in the public key lookup table.
The de-centralized public key management method based on the trust network according to claim 15, wherein the revocation protocol is used by the public key owner to actively apply for revocation and discarding the public key certificate, and after the public key is revoked Unable to activate and reuse; the revocation agreement includes the following process:

1) The revocation request phase: the public key owner generates the revocation public key record and signs the revocation public key record with the private key and sends the revocation request;

2) Record generation phase: each node of the network platform verifies the validity of the signature in the revoked public key record by using the public key in the public key log chain, and records the revoked public key record after passing the verification;

3) Log chain change phase: Each node of the network platform links the undo public key log to the head node of the public key log chain in the public key lookup table.
A decentralized public key management system based on a trust network, characterized in that the public key management system comprises a decentralized network platform and a consistent public key storage structure with network-wide consistency, the centralized network platform The blockchain network, the P2P network, or the distributed database system; the consistent public key storage structure is configured to store the verified public key record.