TWI593267B - Certificateless public key management method with timestamp verification - Google Patents

Description

Voucher-free public key management method with time stamp verification

The invention relates to a voucher-free public key management method with time stamp verification, in particular to a management method for realizing the non-repudiation of a voucher-free public key by means of a fair third party time stamp verification.

At the same time as the continuous development of computer technology today, in order to ensure the security of data transmission using computers and network communication, encryption of data files and digital signatures have become indispensable technologies. In the traditional public key cryptosystem, the sender encrypts the transmitted data by using the key, and the recipient must have the same key to decrypt the received data and obtain the original data content. However, in this way, the sender's public key needs to be credential to ensure its reliability, and the large storage space and calculation time required to manage the voucher become the biggest problem of the traditional public key cryptosystem.

In order to solve the above problem of the public key cryptosystem, an encryption system based on user identity authentication is proposed, which uses the public information of the user, such as an email, a phone number, an identity card number, etc. to generate a public key, the user's key. It is generated by the Private Key Generation Center (PKG). This method can save the procedure of the public key certificate. Avoiding the problem of credential management, but this key generation center can generate the user's complete key, thus deriving the problem of key escrow. If the data of the key generation center is stolen, the security of the encryption system will also be Was questioned.

In response to the above problem, SSAl-Riyami, KGPaterson, "Certificateless public key cryptography", Asiacrypt 2003, Springer-Verlag, LNCS 2894, pp. 452-473, 2003 proposes a voucher-free cryptosystem, as shown in Figure 1. The user terminal 10 transmits the personal identification number 12 to the Key Generation Center (KGC) 11 by using a mobile phone or a computer, and the key generation center 11 calculates a personal user data 13 to generate a partial user key 13 . The partial user key 13 is transmitted back to the user terminal 10. The user terminal 10 sets the secret value and combines the partial user key 13 to form a complete key 14, which does not require a certificate, and does not need to worry about the key. The production center 11 grasps the complete key 14. However, this cryptosystem still has a problem in key management. The user terminal 10 can change the set secret value to generate an infinite number of complete keys 14 by itself, and the key generation center 11 can also randomly select the secret value to forge multiple groups. The complete key 14, thus creating a multi-key condition, cannot be guaranteed to be non-repudiation.

As described above, the inventor of the present invention contemplates and designs a voucher-free public key management method with time stamp verification to improve the lack of the prior art, thereby enhancing the implementation and utilization of the industry.

In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a voucher-free public key management method with time stamp verification to solve the problem that the conventional key cryptosystem cannot ensure its non-repudiation.

According to an aspect of the present invention, a voucher-free public key management method with time stamp verification is provided, which is applicable to signature and verification during file transfer in a communication network, and the method comprises the following steps: setting by a key generation center The master key and the public system parameters; the master key set by the key generation center and the public system parameter, plus the identification code of the user end, extract part of the key and transmit it to the user end; the user end sets the secret value The private key is generated by the secret value and the partial key, and the public key is generated by the secret value and the system parameter; the public key is transmitted to the fair third party, and the fair third party performs the operation by the time stamp to generate the partial public key. The verification parameter is transmitted back to the user end; the user end transmits the public key and part of the public key verification parameter to the verifier, and the verifier performs a set of bilinear operations to verify whether the public key passes the verification; the user end The voucher-free signature is generated by the private key, the secret value and the system parameter, and transmitted to the verifier through the communication network; the verifier uses the public key and the system parameter to verify the voucher-free signature Correctness.

Preferably, the disclosed system parameters may include an additive group of elliptic curves, a multiplicative group of elliptic curves, a hash function, and a public key of a key generation center.

Preferably, the time stamp can be recorded in the impartial third party.

Preferably, the time stamp can be operated to generate a time stamp parameter, and the time stamp parameter includes a one-way hash function value of the fair third party master key and the time stamp glue operation.

Preferably, the partial public key verification parameter may include a first public key verification parameter and a second public key verification parameter.

Preferably, the first public key verification parameter may include a fair third party master key, a time stamp parameter, and a generator of the addition loop group.

Preferably, the second public key verification parameter may include a time stamp parameter and a one-way hash function value of the public key.

As described above, the voucher-free public key management method with time stamp verification according to the present invention may have one or more of the following advantages:

(1) The voucher-free public key management method with time stamp verification can effectively solve the problem that the user end generates multiple sets of unauthenticated keys, thus causing management problems and ensuring that the actually generated keys can be fair. Third-party time stamp records are non-repudiation.

(2) The certificate-free public key management method with time stamp verification can solve the problem of key escrow system key escrow, and prevent the key generation center from randomly selecting the secret value to forge the complete key, and improve the key cryptosystem. safety.

10, 30‧‧‧User end

11, 22, 31‧‧‧ Key Generation Center

12‧‧‧Personal Identification Number

13‧‧‧Part user key

14‧‧‧Complete key

20, 34‧‧‧Recipients

21‧‧‧Transporter

23, 33‧‧‧ Fair third parties

32‧‧‧Complete key

PK‧‧‧ public key

A‧‧‧Second public key verification parameters

T‧‧‧first public key verification parameters

T‧‧‧ time stamp parameters

S1~S7, S6’, S7’‧‧‧ steps

Figure 1 is a schematic diagram of a conventional certificate-free public key management method.

2 is a flow chart of the method for managing a voucher-free public key with time stamp verification according to the present invention.

Figure 3 is a schematic diagram of the voucher-free public key management method with time stamp verification of the present invention.

FIG. 4 is a schematic diagram of a method for encrypting and decrypting a voucher-free public key with time stamp verification according to the present invention.

Figure 5 is a schematic diagram of the fair third party time stamp verification method of the present invention.

Figure 6 is a schematic diagram of a method of verifying a public key of the present invention.

The technical features, contents, advantages and advantages of the present invention will be understood by the reviewing committee, and the present invention will be described in detail with reference to the accompanying drawings. The subject matter is only for the purpose of illustration and description. It is not intended to be a true proportion and precise configuration after the implementation of the present invention. Therefore, the scope and configuration relationship of the attached drawings should not be interpreted or limited. First described.

Please refer to FIG. 2, which is a flowchart of the voucher-free public key management method with time stamp verification according to the present invention. As shown in the figure, the voucher-free public key management method includes the following steps (S1~S7):

Step S1: setting the master key and exposing system parameters by the key generation center. The key generation center may perform an algorithm by the server, select a security parameter, generate a master key that only the key generation center can know, and generate a public system parameter, wherein the public system parameter may include an addition group of the elliptic curve. , the multiplicative group of elliptic curves, the hash function, and the public key of the key generation center.

Step S2: extracting part of the key and transmitting it to the user by using the master key set by the key generation center and the public system parameter, plus the user's identification code. The key generation center executes the algorithm to generate a key by using the aforementioned master key, the public system parameter, and the user's identification code, and the key is a partial key of the user. Here, the user's identification code can be used to disclose information to the user, including phone number, email, ID card number, and the like. After the partial key is generated, the user can extract the partial key and perform subsequent setting steps.

Step S3: The user sets a secret value, and the private key is generated by the secret value and the partial key, and the public key is generated by the secret value and the system parameter. This step is performed on the user side. The secret value selected by the user, combined with the extracted partial key and the public system parameters, can be combined to generate the private key and the public key.

Step S4: The public key is transmitted to the fair third party, and the fair third party performs the operation of the time stamp to generate a partial public key verification parameter, which is transmitted back to the user. In order to prevent the user from selecting different secret values to generate a large number of key authentication keys, the user must first transmit the generated public key to a server of a fair third party, and the fair third party adds the time stamp to perform the operation, and generates a partial public The key verification parameters are passed back to the user. At this time, the fair third party will record the time stamp added by each verification as the verification credential. The time stamp used in the present invention does not only refer to a time-related message stamp, but has a time stamp that can be understood by a person of ordinary skill in the art, and can also be a stamp that is not related to time, such as arbitrarily generated garbled characters. The time stamp used in the verification, whether or not related to time, can be stored in a fair third party as a record of verification.

Step S5: The user transmits the public key and part of the public key verification parameter to the verifier, and the verifier performs a set of bilinear operations to verify whether the public key passes the verification. After obtaining the partial public key verification parameters, the user transmits the public key together with the partial public key verification parameters to the verifier. The verifier must perform a set of bilinear function operations after receiving, and check whether the public key is passed. The public key of the fair third party verification, if it is, can be used as the public key of the verification signature; if not, the user must be notified to retransmit the verified public key.

Step S6: The user generates a certificate-free signature for a file by using a private key, a secret value, and a system parameter, and transmits the certificate to the verifier. After the user authenticates the public key through a fair third party, if the signature file needs to be transmitted to the verifier, the document can be signed by the private key, the secret value and the system parameter, and the certificate-free signature is generated and then transmitted. To the verifier.

Step S7: The verifier verifies the correctness of the voucher-free signature through the public key and the system parameter. After receiving the verifier, the certifier can confirm whether the received voucher is correct by receiving the public key verified. If it is correct, confirm that the voucher is valid, and the file is a valid document signed correctly; If the signature fails to pass the verification, the user is notified that the certificate-free signature cannot be verified, and the new certificate-free signature must be re-transmitted for verification.

The above-mentioned various key and signature file management methods are applicable to file transfer in a communication network, that is, through a communication network between a host computer and a certifier side host or a computer, or a key generation center and Transmit and receive between fair third party servers. At the same time, in response to the above-mentioned steps of exempting the voucher, in addition to being applied to the transfer of the file, the identity of the sender is also applied to the encryption and decryption of the file. For example, the step of signing the file in step S6 is changed to the certifier side to encrypt the file, and the ciphertext is generated, and then transmitted to the user end. When the signature verification is performed in step S7 and the user side decrypts the file, the step of the voucher-free public key management method may be converted to the encryption and decryption of the file.

Please refer to FIG. 3, which is a schematic diagram of a voucher-free public key management method with time stamp verification according to the present invention. As shown, the voucher-free public key management method includes a receiver 20, a sender 21, a key generation center 22, and a fair third party 23. First, the key generation center 22 performs step S1 to set the master key and disclose system parameters. The steps performed here are the same as those of the previous embodiment, and therefore the details of the steps are referred to the description of FIG. 1 without repeating the description. Then, in step S2, the master key is extracted and the system parameters are disclosed to the transmitter terminal 21. The transmitter terminal 21 is the user terminal of the previous embodiment, and may be a user's computer, mobile phone or the like. The sender 21 selects the secret value of the individual by itself in step S3, and generates a public key and a private key based on the secret value. At this time, the transmitter 21 must perform step S4 to transmit the generated public key to the fair third party 23 The server performs time stamp verification. At this time, the third party 23 records the time stamp information, and generates a partial public key verification parameter to be transmitted back to the transmitter terminal 21. Next, the sender 21 transmits the generated public key and part of the public key verification parameter transmitted by the impartial third party 23 to the receiver 20, and the receiver performs step S5 to verify whether the public key is verified by the time stamp of the impartial third party 23. The receiver 20 can also be a receiver computer, a mobile phone, or the like. After the above steps are completed, the transmitter 21 can perform the certificate-free signature of step S6, and generate a certificate-free signature for the file to be transmitted to the receiver 20 by using the private key and the secret value, and then use the communication network. It is passed to the receiver end 20. Finally, the receiver 20 performs the step S7 by using the previously received public key to verify the correctness of the certificate-free signature, thereby eliminating the voucher signature as the basis for the correctness of the document.

In the actual situation, the transmitter 21 must perform the preparation procedures of the above steps S1 to S4 before signing the file, and generate its own public key, private key and partial public key verification parameters. Then, the public key and public key verification parameters are transmitted to the receiver 20 for verification. After the recipient has completed the verification of the public key, the transmitter 21 can use the originally generated private key to perform the file or file to be transmitted. The signature is transmitted to the receiver 20, and after the recipient 20 receives the signature and the file, the verified public key can be used to verify the document signature, thereby confirming the correctness of the file. Similarly, the step of signing the file may also be applied to the encryption and decryption of the file. As shown in FIG. 4, it is a schematic diagram of the method for encrypting and decrypting the voucher-free public key with time stamp verification of the present invention. . The content of step S1 to step S5 is similar to that of the foregoing embodiment, so the description is not repeated. The difference is that step S6' is changed to the recipient side to encrypt the file, and the verified public key is used to encrypt the file to generate a secret. After the text is transmitted to the transmitter side, the original receiver side performs the verification to the step S7' to decrypt the ciphertext by the sender side, that is, the encrypted key is decrypted by using the original generated private key. Original file The original signature method is applied to the encryption and decryption of the file, so that the voucher-free public key management method with time stamp verification can also be applied to the encrypted file.

Please refer to FIG. 5, which is a schematic diagram of the fair third party time stamp verification method of the present invention. As shown in the figure, the user terminal 30 transmits the personal identification code to the key generation center 31, and the key generation center 31 generates a partial key back to the use by calculating the master key and the public system parameters. End 30, this part is similar to that shown in Fig. 1 and therefore will not be described again. When the user terminal 30 receives the partial key, the complete key 32, including the private key and the public key, can be generated according to the secret value selected by the user. However, instead of directly generating a certificate-free signature for the recipient to verify, the public key PK is sent to the fair third party 33 for time stamp verification, and the partial public key verification parameters T and A generated by the fair third party 33 operation. Then pass back to the user end 30.

The fair third party 33 described herein is a mechanism independent of the key generation center 31, which can store the time stamp data for verification, and provides a record of the time stamp verification as evidence in the event of a dispute arising from the subsequent encryption process, thereby avoiding the user. Unlimited selection of secret values to generate a public key, signed with an unverified key. When the fair third party 33 performs the operation, the time stamp parameter may be generated by using the selected time stamp, and the stamp parameter may be represented by t=H ₁ (s∥timestamp), where s is the master key of the impartial third party. Timestamp is a time stamp, ∥ is a sticky operation, H ₁ is a one-way hash function, H ₁ (X) is the hash value of message X, H ₁ : {0, 1} * → Zq *. Therefore, the timestamp parameter can be a one-way hash function value of a fair third-party master key and a time-stack glue operation. At a time stamp parameter may further generate a first public key to verify the operational parameters of a public key and a second authentication parameters T A, where the first public key of the authentication parameter T = stP, wherein P ₁ is a point G, the system One parameter in the parameter, and G ₁ is an addition cycle group, which is a parameter in the third-party system parameters; and the second public key verification parameter A=t H ₂ (PK), where H ₂ is a one-way hash function , H ₂ (X) is the hash value of the message X, and H ₂ : G ₁ → G ₁ .

Please refer to FIG. 6 again, which is a schematic diagram of the method for verifying the public key of the present invention. As shown in the figure, the user terminal 30 transmits the public key PK, the partial public key verification parameter including the first public key verification parameter T and the second public key verification parameter A to the receiver end 34, and the receiver end is provided by a group. A bilinear operation is performed to verify whether the public key PK has passed verification. A bilinear function is a property of an elliptic curve, from one group to another, G ₁ is an additive cycle group on an elliptic curve, G ₂ is a multiplicative cycle group on an elliptic curve, and the order of G ₁ and G ₂ The order is the same prime number q, where P is the generator of G ₁ . Bilinear pairing can be expressed as: e: G ₁ × G ₁ → G ₂ and should have the following three properties: (1) bilinear: for any integer x, y Z*q, there exists e(xP, yP)=e(P,P) ^xy ,P G ₁ ; (2) Non-degenerate: Assuming P is a generator of G ₁ , then e(P, P) is the generator of G ₂ ; (3) Computability: P, Q G ₁ , there is a polynomial time efficient algorithm to calculate e(P, Q) G ₂ .

After receiving the public key PK, the first public key verification parameter T and the second public key verification parameter A, the receiver side 34 performs a set of bilinear operations e(A, P _pub )=e(H(PK), T ) to verify the public key, where P _pub is the public key of the third party, and the value in the system parameter is P _pub = sP. If the results of the two bilinear functions are equal, it is confirmed as the authenticated public key PK, and the client 30 can then generate a certificate-free signature for the file by the private key, and transmit it to the receiver 34, and the recipient End 34 uses the authenticated public key PK to verify the correctness of the voucher-free signature.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

S1~S7‧‧‧ steps

Claims (6)

A voucher-free public key authentication management method with time stamp verification is applicable to signature and verification of file transfer in a communication network, and the method comprises the following steps: setting a master key by a key generation center and a public system parameter; the master key set by the key generation center and the public system parameter, plus a user end identification code, extract a part of the key and transmit to the user end; via the use Setting a secret value by using the secret value together with the partial key to generate a private key, and generating a public key by using the secret value and a system parameter; transmitting the public key to an impartial third party, The unbiased third party generates a part of the public key verification parameter by using a time stamp to be transmitted back to the user end; the user end transmits the public key and the part of the public key verification parameter to a verifier. Performing a set of bilinear operations by the verifier to verify whether the public key passes the verification; the user end generates a voucher-free signature for a file by using the private key, the secret value, and the system parameter, and The pass The network transmits to the verifier; and the verifier verifies the correctness of the voucher-free signature through the public key and the system parameter; wherein the partial public key verification parameter includes a first public key verification parameter and a The second public key verification parameter. The method for managing certificate-free public key authentication with time stamp verification as described in claim 1, wherein the disclosed system parameter includes an additive group of elliptic curves, The multiplicative group of elliptic curves, the hash function, and one of the key generation centers expose the key. The method for managing a certificate-free public key certificate with time stamp verification as described in claim 1 of the patent application scope, wherein the time stamp is recorded in the impartial third party. The method for managing a certificate-free public key authentication with time stamp verification as described in claim 1, wherein the time stamp is operated to generate a time stamp parameter, wherein the time stamp parameter includes a fair third party master key and the time One of the one-way hash function values. The voucher-free public key authentication management method with time stamp verification as described in claim 4, wherein the first public key verification parameter includes a fair third party master key, the time stamp parameter, and an addition cycle group A generator. The voucher-free public key authentication management method with time stamp verification according to claim 4, wherein the second public key verification parameter includes the time stamp parameter and a one-way hash function value of the public key.