KR20180089951A - Method and system for processing transaction of electronic cash - Google Patents

Abstract

Disclosed are an electronic cash transaction method and a system thereof, capable of safely and easily performing a peer-to-peer (P2P) electronic cash movement without using a server connected to a network. According to the present invention, the method comprises: a step in which a receiving side module designates an amount of electronic cash to be requested and generates a random number; a step in which the receiving side module generates a first cryptogram based on the amount and the random number; a step in which a transmitting side module generates a second cryptogram based on the first cryptogram; a step in which an issuing side module decrypts the second cryptogram with a transmitting side public key and a receiving side public key; a step in which the issuing side module generates a third cryptogram based on the second cryptogram; a step in which the receiving side module decrypts the third cryptogram with the transmitting side public key and an issuing side public key; and a step in which the receiving side module determines whether a result of decrypting the third cryptogram is equal to the amount and the random number, wherein the transmitting side public key, the issuing side public key and the receiving side public key are generated as an odd number by an F function.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic money transaction method and system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic money transaction method and system, and more particularly, to an electronic money transaction method and system that enable electronic money to be used more easily in P2P transactions.

Block Chain, also known as bit coin security technology, is also called a public transaction book, and is a technique to prevent hacking that may occur when trading with electronic money (virtual currency).

The traditional electronic money transfer / payment method is centralized to keep all transaction records on the central server, while the block chain sends transaction details to all users participating in the transaction and contrasts them to prevent data tampering have.

The existing electronic money transfer / payment method described above requires book management and should be processed in a central server through a network. Book management requires the resources of the data store, and a server system connected to the network is necessary to be processed at the central server.

On the other hand, each user using the block chain has to store not only his / her transaction history but also transaction details of all other users involved in the transaction, thus causing storage space problems. So, in some cases, an intermediate server may be utilized. In this case, an intermediate server connected to the network must be separately provided.

In addition, since the block chain uses individual distributed ledgers, when a transaction occurs, it is necessary to update the record of the transactions in all the distributed ledgers. At this time, as the number of users using the block chain increases, the time required to update the record details in all the users' ledgers becomes longer, and a problem occurs that a lot of time is required to be completed.

On the other hand, since the existing prepaid charging card must have a cryptographic key on the receiving side, a hardware device such as a SAM (Secure Access Module) is necessarily required. However, the present SAM has a problem in that it can acquire money by accessing all the cards.

Prior Art 1: Korean Patent No. 10-1637854 (a public key certificate-based issuing system based on a block chain, an authorized certificate issuing method based on a block chain using the same, and a public key certificate authentication system based on a block chain) Authorized certificate authentication method based on block chain) Prior Art 2: Korean Registration No. 10-1233925 (ID-based encryption and signing device and method, secret key issuing server and method) Prior Art 3: Korean Patent No. 10-1660627 (Method and Apparatus for Protecting Encrypted Money Transactions) Prior Art 4: Korean Patent No. 10-0358426 (Electronic Cash Transaction Method)

Disclosure of Invention Technical Problem [8] The present invention has been proposed in order to solve the above-described problems of the related art, and provides an electronic money transaction method and system that can safely and easily move electronic money between P2Ps without using a server connected to a network. There is a purpose.

In order to achieve the above object, an electronic money transaction method according to a preferred embodiment of the present invention is a transaction method which is requested by a receiving side module for electronic money issued by a issuing side module and paid by a transmitting side module, The module designating an amount of electronic money to be requested and generating a random number; The receiving module generating a first ciphertext based on the amount and the random number; The transmitting module generating a second cipher text based on the first cipher text; The issuing side module decrypting the second cipher text with the transmitting public key and the receiving public key; The issuer-side module generating a third ciphertext based on the second ciphertext; The receiving module decrypting the third cipher text with a transmitting public key and a issuing public key; And a step in which the receiving module decides whether the result of decoding the third cipher text matches the amount and the random number, and wherein the transmitting side public key, the issuing side public key, and the receiving side public key Are generated in an odd number by the F function.

The F function may be a single function or a hash function that outputs an odd number for all input values.

The transmitting side public key, the issuing side public key, and the receiving side public key have the same common factor N (N = p * q, p = 2p '+ 1, q = 2q' + 1 Is a prime number, and p and q are different prime numbers).

The step of decrypting the second cipher text with the transmission side public key and the reception side public key may include extracting the amount corresponding to the decryption and updating the information of the amount storage unit in the issuing side module.

The third ciphertext may be passed to the receiver module via the transmitter module.

Wherein the step of determining whether the decryption result of the third ciphertext matches the amount and the random number includes the step of determining whether the decryption result of the third ciphertext matches the amount and the random number, And updating the information of the amount storage unit in the side module.

An electronic money transaction system according to a preferred embodiment of the present invention is a transaction system that is requested by a receiving side module for an electronic money issued by a issuing side module and paid by a transmitting side module, A random number generator for generating a random number; A receiving key storage unit for storing a receiving side secret key; And generating a ciphertext using the receiving secret key and transmitting the ciphertext to the transmitting module, and transmitting the final ciphertext corresponding to the ciphertext sequentially encrypted through the transmitting module and the issuer module And a process processor for decrypting the decrypted cipher text with the transmission side public key and the issuing side public key and determining whether the result of decoding the final cipher text matches the amount and the random number, The public key is generated in an odd number by the F function.

The transmitting side public key and the issuing side public key have the same common factor N (N = p * q, p = 2p '+ 1, q = 2q' + 1 And q may be different prime numbers).

Side module, the issuing-side module decrypts the encrypted ciphertext again with the transmitting-side public key and the receiving-side public key in accordance with the cipher text in the receiving-side module being re-encrypted in the transmitting-side module, Is an odd function generated by an F function, the F function is a single function or a hash function that outputs an odd number for all input values, and the receiving side public key is a function of the transmitting side public key and the issuing side public key A common factor (N) can be used.

The receiving key storage unit may be located in a universal subscriber identity module (USIM) or a trust zone of the receiving module.

An electronic money transaction system according to another preferred embodiment of the present invention is a transaction system that is requested by a receiving side module for an electronic money issued by a issuing side module and paid by a transmitting side module, A issuing key storage unit for storing a side secret key; And a first ciphertext based on the amount requested by the receiving module and a random number generated by the receiving module, the second ciphertext being encrypted with a second ciphertext in the transmitting module, And a process processor for generating a third cipher text by using the issuing secret key and transmitting the second cipher text to the receiving module via the transmitting module, The receiving side public key is generated by an F function in an odd number.

Wherein the process processing unit generates and provides a common factor that can be commonly used in the transmitting module and the receiving module, and the transmitting public key and the receiving public key use the same common factor, (P 'and q' are prime numbers, p and q are different prime numbers, and N is a common factor).

Wherein the receiving side module determines whether the result of decoding the third cipher text by the transmitting side public key and the issuing side public key matches the amount and the random number, the issuing side public key is generated in an odd number by the F function, The F function is a single function or a hash function that outputs an odd number for all input values, and the issuing public key can use a common factor used by the transmitting public key and the receiving public key.

The issue key storage unit may be located in a universal subscriber identity module (USIM) or a trust zone of the issuer-side module.

According to the present invention having such a configuration, the amount to be paid at the receiving side is specified, and a random number is generated to start the transaction. That is, the starting point of the transaction is not the sender and the issuer but the receiver.

Since the issuing public key, the transmitting public key, and the receiving public key use the same common factor (N) in mutual transactions, the CA (Certification Authority) (CA), the RA Registration Authority). In other words, by using ID-based cryptography for reliable identification between both parties, a server such as a CA (Certification Authority) (CA) or RA (Registration Authority) It can be verified directly by the terminal without being dependent on it. Thus, by using ID-based cryptography for authentic identity verification between both parties, it is possible to prevent fraud by public key exchange in the conventional public key cryptosystem.

Since the random numbers are associated with each other in a one-to-one correspondence with respect to all the amounts, if the random number of the corresponding amount is compared with the first generated random number as a result of decoding at the receiving end, the transaction is not performed. The problem of payment can be solved.

1 is a configuration diagram of an electronic money transaction system according to an embodiment of the present invention.
2 is a flowchart illustrating an electronic money transaction method according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a configuration diagram of an electronic money transaction system according to an embodiment of the present invention.

The electronic money transaction system according to the embodiment of the present invention includes an issuer terminal 10, a transmitting terminal 20, and a receiving terminal 30. Here, the issuer terminal 10, the transmitting terminal 20, and the receiving terminal 30 are represented as a issuing module or a issuing module, a transmitting module or a transmitting module, a receiving module, or a receiving module It can be done. On the other hand, the issuer terminal 10, the transmitting terminal 20, and the receiving terminal 30 may be electronic money transaction devices.

1, the issuing company terminal 10 and the transmitting terminal 20 are connected by a network (not shown), and the transmitting terminal 20 and the receiving terminal 30 are connected by a network (not shown).

The issuing company terminal 10 and the transmitting terminal 20 can perform data communication with each other and the transmitting terminal 20 and the receiving terminal 30 can perform data communication with each other.

The term " network " includes both a wired communication network and a wireless communication network. The term " communication network "

The issuer terminal 10 is a terminal of an issuer (service provider) for providing an application (app) capable of trading electronic money between P2Ps.

The issuer terminal 10 can issue electronic money. Here, it is assumed that the issuer is reliable.

The issuing company terminal 10 can generate a common factor N that can be commonly used by the transmitting terminal 20 and the receiving terminal 30. [ The issuing company terminal 10 sends the generated common factor N to the transmitting terminal 20 and the receiving terminal 30. [

For example, the issuer terminal 10 generates a prime number p = 2p '+ 1 and a prime number q = 2q' + 1, where p 'and q' are prime numbers and p and q are prime numbers different from each other. Here, the common factor (N) = p * q. In other words, multiplying two different prime numbers (p, q) can be called a common factor (N). The common factor N may be stored in the transmitting terminal 20 and the receiving terminal 30 and used in the encryption, decryption and authentication steps. The value of (p-1) * (q-1) may be phi (phi) (N). Phi (phi) (N) may be a secret key generation factor.

The issuer terminal 10 can receive and decrypt the cipher text generated in the transmitting terminal 20. [ Here, the cipher text generated at the transmitting terminal 20 is generated by encrypting the cipher text generated at the receiving terminal 30 with the transmitting private key of the corresponding transmitting terminal 20. The cipher text generated by the receiving terminal 30 is transmitted to the recipient terminal 30 through a data A∥R (that is, a sequence) obtained by concatenating the amount A requested by the receiving terminal 30 and the random number R And encrypted with the receiving side secret key. Therefore, the cipher text generated by the receiving terminal 30 may be referred to as a first cipher text or a first cipher text, and the cipher text generated by the transmitting terminal 20 may be referred to as a second cipher text or a second cipher text.

In decrypting the cipher text (second cipher text) generated by the transmitting terminal 20, the issuing company terminal 10 transmits the second cipher text to the transmitting side public key e2, N corresponding to the transmitting side secret key, Side public key e1, N corresponding to the key.

The issuer terminal 10 decrypts the second cipher text, extracts the amount, and updates the internal amount storage unit.

Also, the issuer terminal 10 may generate a third cipher text (or a third cipher text) in which the second cipher text is encrypted with the issuer secret key of the issuer terminal 10.

The issuer terminal 10 transmits the third cipher text to the transmitting terminal 20.

The issuer terminal 10 may include a issued key storage unit 11, a money storage unit 12, a process processing unit 13, and an interface unit 14.

The issued key storage unit 11 stores the secret key of the issuer terminal 10.

The amount storage unit 12 stores the amount requested from the receiving terminal 30 to the transmitting terminal 20. That is, the issuer terminal 10 can decrypt the cipher text (second cipher text, a result obtained by encrypting the first cipher text generated by the receiving terminal 30 with the transmitting secret key) generated by the transmitting terminal 20. The amount storage unit 12 stores the amount extracted through such decryption (i.e., the amount requested to the transmitting terminal 20).

Also, the amount storage unit 12 can be updated based on the extracted amount.

It is preferable that the issue key storage unit 11 and the amount storage unit 12 are located in a universal subscriber identity module (USIM) or a trust zone of the issuer terminal 10, as needed. A USIM or a trust zone can be said to be a memory area inaccessible to the user. The issuing secret key and the amount are security sensitive information. When the issued key storage unit 11 and the money storage unit 12 are located in the USIM or the trust zone, access to the issuer secret key and the amount of money can be blocked.

The process processing unit 13 controls the overall operation of the issuer terminal 10.

The process processing unit 13 generates a common factor N that can be commonly used by the transmitting terminal 20 and the receiving terminal 30 and transmits the common factor N to the transmitting terminal 20 and the receiving-side terminal 30, respectively.

The process processing unit 13 can generate the issuing secret key. The process processing unit 13 stores the issuing secret key in the issuing key storage unit 11. [ Of course, unlike the case where the process processing unit 13 generates the issuing secret key, the issuing secret key may be preset in the designing stage of the issuer terminal 10. [

The process processing unit 13 may perform operations such as increasing or decreasing the amount of money in the amount storage unit 12. [

The process processing unit 13 transmits the second cipher text from the transmitting terminal 20 to the transmitting side public key e2, N corresponding to the transmitting side secret key and the receiving side public key e1, N ). ≪ / RTI > To this end, the process processing unit 13 may store the transmitting public key and the receiving public key.

The first cipher text generated by the receiving terminal 30 is a data A∥R (that is, a sequence) obtained by concatenating the amount A requested by the receiving terminal 30 and the random number R And encrypted with the receiving side secret key. The second cipher text in the transmitting terminal 20 is the above-mentioned first cipher text encrypted with the transmitting secret key. Accordingly, the process processing unit 13 first decrypts the second cipher text with the transmission side public key corresponding to the transmission side secret key, and then decrypts the second cipher text with the reception side public key corresponding to the reception side secret key again.

By this decryption, the process processing unit 13 can extract the amount in the second cipher text, and can update the amount storage unit 12 based on the extracted amount. Through this decryption procedure, the process processing unit 13 can accurately grasp the amount requested by the receiving-side terminal 30 to the transmitting-side terminal 20.

The process processor 13 generates a third cipher text by encrypting the second cipher text with the issuer secret key of the issuer terminal 10 and transmits the third cipher text to the transmitting terminal 20 via the interface unit 14 Lt; / RTI > At this time, since the random number R in the receiving terminal 30 is an unpredictable random number, the process processing unit 13 can not generate a random number equal to the random number R generated in the receiving terminal 30. Accordingly, the process processing unit 13 can not forge or modify the sequence (amount A (A) ∥ random number R) originally generated at the receiving terminal 30. The receiving terminal 30 will not receive the amount because the random number is different even if the forgery and falsification is performed. This can solve the double payment problem.

The interface unit 14 can perform wire / wireless communication with the transmitting terminal 20.

The interface unit 14 can receive the second cipher text from the transmitting terminal 20 and apply it to the process processing unit 13. [

Further, the interface unit 14 can transmit the third cipher text from the process processing unit 13 to the transmitting terminal 20.

The interface unit 14 includes a communication module (not shown) that can perform communication such as Wi-Fi communication, Bluetooth communication, NFC (Near Field Communication), and the like with the transmitting terminal 20. On the other hand, the interface unit 14 may transmit the third cipher text using the QR code.

Although the process processing unit 13 and the interface unit 14 are configured to be independent from each other in FIG. 1, the interface unit 14 may be included in the process processing unit 13, if necessary.

The transmitting terminal 20 can encrypt the cipher text generated by the receiving terminal 30 (i.e., the first cipher text). When encrypting in the transmitting terminal 20, the transmitting terminal 20 can generate the second cipher text by encrypting the first cipher text with the transmitting private key of the transmitting terminal 20 concerned.

The transmitting terminal 20 transmits the generated second cipher text to the issuer terminal 10.

The transmitting side terminal 20 transfers the third cipher text from the issuing company terminal 10 to the receiving side terminal 30.

The receiving side terminal 30 is opposed to the transmitting side terminal 20 only and therefore the receiving side terminal 30 can not receive the electronic money of the predetermined amount from the receiving side terminal 30 As a means of payment.

The transmitting side terminal 20 can communicate with the issuing company terminal 10 or the receiving side terminal 30 through Wi-Fi communication, Bluetooth communication, NFC (Near Field Communication), or the like. Accordingly, the transmitting terminal 20 may include a communication module for communicating with the issuing company terminal 10 or the receiving terminal 30, or the like. If necessary, the transmitting terminal 20 may transmit the second cipher text using the QR code.

The transmitting side terminal 20 may be various smart devices such as a smart phone, a smart note, a tablet PC and the like as a wireless communication device which is guaranteed to be portable and mobility.

The above-described transmitting terminal 20 may include a transmission key storage unit 21, a process processing unit 22, and an interface unit 23.

The transmission key storage unit 21 stores the secret key of the transmitting terminal 20.

If necessary, the transmission key storage unit 21 may be located in a universal subscriber identity module (USIM) or a trust zone of the transmitting terminal 20. A USIM or a trust zone can be said to be a memory area inaccessible to the user. The sender secret key is security sensitive information. By placing the transmission key storage unit 21 in the USIM or the trust zone, it is possible to block a hacker or the like from accessing the transmitting side secret key.

The process processing unit 22 controls the overall operation of the transmitting terminal 20.

The process processing unit 22 can generate the transmitting secret key, and stores the generated transmitting secret key in the transmission key storing unit 21. [ Of course, the transmitting side secret key may be preset in the design stage of the transmitting side terminal 20, unlike the case where the process processing unit 22 generates the transmitting side secret key.

The process processing unit 22 can encrypt the cipher text (i.e., the first cipher text) generated in the receiving terminal 30. [ That is, the process processor 22 can generate the second cipher text by encrypting the first cipher text with the transmitting secret key. At this time, since the random number R in the receiving terminal 30 is an unpredictable random number, the process processing unit 22 can not generate the same random number as the random number R generated in the receiving terminal 30. Accordingly, the process processing unit 22 can not forge or modify the sequence (amount A (A) ∥ random number R) originally generated by the receiving side terminal 30. The receiving terminal 30 will not receive the amount because the random number is different even if the forgery and falsification is performed. This can solve the double payment problem.

The process processing unit 22 transmits the generated second cipher text to the issuer terminal 10 through the interface unit 23.

The process processing unit 22 controls the interface unit 23 so that the third cipher text from the issuer terminal 10 can be transmitted to the receiving terminal 30. [

The interface unit 23 can perform wire / wireless communication with the issuer terminal 10 and the receiving terminal 30. [

The interface unit 23 may transmit the second cipher text generated by the process processing unit 22 to the issuer terminal 10 and may transmit the third cipher text from the issuer terminal 10 to the receiving terminal 30 .

The interface unit 23 includes a communication module (not shown) that can perform communication such as Wi-Fi communication, Bluetooth communication, and NFC (Near Field Communication) with the issuer terminal 10 and the receiving terminal 30 . On the other hand, the interface unit 23 may transmit the third cipher text using the QR code.

1, the process processing unit 22 and the interface unit 23 are independently configured. However, the interface unit 23 may be included in the process processing unit 22, if necessary.

The receiving side terminal 30 generates a random number. At this time, the random number has an unpredictable value in the issuer terminal 10 and the transmitting terminal 20.

In the case of the electronic money such as the conventional bit coin, the sending side tries to pay the electronic money of a predetermined amount to only one person, but there is a possibility of the double payment that the electronic money is paid again to another person by mistake.

That is, in the conventional method, the sender became the subject of the transaction and remitted electronic money of a predetermined amount. This causes the problem of double payment as described above.

However, in the embodiment of the present invention, the receiving side terminal 30 becomes the subject of the transaction start. That is, the receiving terminal 30 specifies the amount to be received, generates a random number, generates a first cipher text based on the specified amount and the random number, and transmits the first cipher text to the transmitting terminal 20. Thereafter, the transmitting terminal 20 encrypts the first cipher text and sends it to the issuer terminal 10 as a second cipher text, and the issuer terminal 10 encrypts the second cipher text to form a third cipher text, 30). The receiving terminal 30 determines that the transaction is a normal transaction when the amount and the random number according to the decryption result of the third cipher text are the same as the amount and the random number used for creating the first cipher text, . However, if the amount and the random number according to the result of decrypting the third cipher text are not equal to the amount and the random number used in creating the first cipher text, it is determined that the transaction is abnormal and the transaction is not performed (i.e., the electronic money is not received).

As described above, if the receiving terminal 30 generates a random number and utilizes it as a cipher text, the problem of double payment can be effectively solved.

In this way, the receiving terminal 30 can generate the first cipher text by encrypting the amount to be paid from the transmitting terminal 20 and a predetermined random number using the receiving private key of the receiving terminal 30.

The receiving side terminal 30 transmits the first cipher text to the transmitting side terminal 20.

The receiving side terminal 30 can decrypt the third cipher text received from the issuing terminal 10 via the transmitting side terminal 20. [ At this time, the receiving side terminal 30 decrypts the third cipher text into the issuing public key e3, N corresponding to the issuing private key and the receiving public key e1, N corresponding to the receiving secret key. Then, the receiving side terminal 30 determines whether the amount and the random number included in the decoded result (for example, the decrypted message) coincide with the amount and the random number used in generating the first ciphertext. According to the determination result, the receiving side terminal 30 can update the amount storage unit and complete the transaction.

The receiving side terminal 30 can communicate with the transmitting side terminal 20 via Wi-Fi communication, Bluetooth communication, NFC (Near Field Communication), or the like. Accordingly, the receiving terminal 30 may include a communication module for communicating with the transmitting terminal 20, and the like. If necessary, the receiving-side terminal 30 may scan the cipher text on the QR code with a QR code scanner and decode it.

The receiving terminal 30 may be a terminal installed at an affiliated store. If necessary, the receiving terminal 30 may be a smart device such as a smart phone, a smart note, a tablet PC, or the like.

In the embodiment of the present invention described above, it is preferable that the transmitting side public key e2, N, the issuing side public key e3, N and the receiving side public key e1, N are generated in an odd number by the F function. That is, in order to use all kinds of identifiers as key values of the public key, it is preferable to generate the transmitting public key, the issuing public key, and the receiving public key in an odd number. The F function is a hash function or hash function that outputs an odd number for all input values.

For example, the sender public key e2, N, the issuer public key e3, N, and the receiver public key e1, N may be generated in the following manner. First, a prime number p = 2p '+ 1, a prime q = 2q' + 1, where p 'and q' are prime numbers, and p and q are different prime numbers. Let phi (phi) (N) = (p-1) * (q-1) be N (common factor) = p * q. The exponents e1, e2, and e3 of each public key are an integer that is greater than 1 and less than or equal to phi (N), and is different from py (N) (indicating that there is no common divisor except for 1 between multiple numbers) And it is preferable to make the number of the data to be an odd number so that all data (for example, an identifier) can be used as a key value. If the exponents e1, e2, and e3 are set to an odd number, all kinds of identifiers can be used as public keys.

Of course, from the selected exponents e1, e2, and e3, a number d that satisfies d = 1 / e mod? (Phi) (N) is calculated. The d thus calculated becomes a secret key (private key). That is, d made on the basis of e1 can be the secret key of the receiving terminal 30, d made on the basis of e2 can be the secret key of the transmitting terminal 20, and d May be the secret key of the issuer terminal 10.

The reason why the public key should be an odd number is as follows. (N) = (p-1) * (q-1), the public key e ( e1, e2, and e3 must have a relationship of "small" with Φ (phi) (N) (principle of RSA cryptography). The secret key d is defined as the reciprocal of the public key e, d = 1 / e mod Φ (phi) (N). If e and Φ (phi) (N) (1 / e) will not appear.

(Phi) (N) = (p-1) (1) is obtained again by taking the example as p = 2 * p '+ 1 and q = 2 * q' + 1 in the above example, ) * (q * 1) = (2 * p '+ 1-1) * (2 * q' + 1-1) = '. That is, Φ (phi) (N) is always a multiple of 4. Therefore, to select the public key e that will always be "small" with phi (phi) (N), we make odd number e. When e is an odd number by the F function, it is always "small" with Φ (phi) (N) which is a multiple of 4.

And, the unison function is a function that makes x1! = X2 ==> F (x1)! = F (x2) under all conditions and the hash function under certain conditions. That is, the public key e is different for each user identifier. If the user identifiers are different and the public keys are the same, it is impossible to identify them as different users. For example, in the case of F (x) = x2 (not a monotone function), if the identifier of A is -1 and the identifier of B is 1, the public key becomes equal to 1. F (x) = 2 * x + 1, F (X) = 2 * logx + 1, F Can be defined.

The receiving terminal 30 includes a random number generating unit 31, a receiving key storing unit 32, a money storing unit 33, a process processing unit 34, and an interface unit 35.

The random number generation unit 31 can generate the random number R. [ Here, the method of generating the random number R may use any one or more of various conventional random number generation methods.

The reception key storage unit 32 stores the secret key of the reception-side terminal 30.

The amount storage unit 33 stores the amount information requested or requested by the transmitting terminal 20 and the updated information upon receipt of a predetermined amount from the transmitting terminal 20. [

The receiving key storage unit 32 and the amount storage unit 33 may be located in a universal subscriber identity module (USIM) or a trust zone of the corresponding receiving terminal 30. [ A USIM or a trust zone can be said to be a memory area inaccessible to the user. The receiving secret key and the amount are security sensitive information. When the reception key storage unit 32 and the money storage unit 33 are located in the USIM or the trust zone, access to the secret key of the reception side and the amount of money by the hacker or the like can be blocked.

The process processing unit 34 controls the overall operation of the receiving side terminal 30.

The process processing unit 34 designates the amount A to be paid from the transmitting terminal 20 and transmits data (A) obtained by concatenating the specified amount A and the random number R from the random number generating unit 31 A? R) with the secret key of the receiving side to generate the first cipher text.

The process processing unit 34 transmits the first cipher text to the transmitting terminal 20 via the interface unit 35. [

Meanwhile, the process processing unit 34 can decrypt the third cipher text received from the issuer terminal 10 via the interface unit 35 via the transmitting terminal 20. At this time, the process processing unit 34 decrypts the third cipher text with the issuing public key corresponding to the issuing secret key and the receiving public key corresponding to the receiving secret key.

The process processor 34 judges whether or not the amount A 'and the random number R' of the decoded result (for example, a decrypted message) coincide with the amount A and the random number R used in generating the first ciphertext do.

The process processing unit 34 can update the amount storage unit 33 according to the determination result to complete the transaction.

The interface unit 35 can perform wire / wireless communication with the transmitting terminal 20.

The interface unit 35 can transmit the first cipher text generated by the process processing unit 34 to the transmitting terminal 20 and receive the third cipher text transmitted through the transmitting terminal 20. [

The interface unit 35 includes a communication module (not shown) that can perform communication such as Wi-Fi communication, Bluetooth communication, NFC (Near Field Communication) and the like with the transmitting terminal 20. On the other hand, the interface unit 35 may transmit the first cipher text using the QR code.

1, the process processing unit 34 and the interface unit 35 are independently configured. However, the interface unit 35 may be included in the process processing unit 34 as needed.

Hereinafter, an electronic money transaction method according to an embodiment of the present invention will be described with reference to the flowchart of Fig.

The receiving side terminal 30 designates the amount A to be paid from the transmitting side terminal 20 and generates a random number R therefor (S10).

The receiving side terminal 30 generates the first cipher text E1 by encrypting the data A∥R (i.e., sequence) in which the amount A and the random number R are concatenated with the receiving side secret key (S12). A common factor (N) will be used when generating the first cipher text (E1).

Then, the receiving-side terminal 30 transmits the first cipher text E1 to the transmitting-side terminal 20 (S14).

Accordingly, the transmitting terminal 20 encrypts the received first cipher text E1 with the transmitting secret key to generate the second cipher text E2 (S16). A common factor (N) will be used when generating the second cipher text (E2).

Then, the transmitting terminal 20 transmits the second cipher text E2 to the issuing company terminal 10 (S18).

Accordingly, the issuer terminal 10 decrypts the second cipher text E2 with the transmission side public key and the reception side public key. That is, the issuer terminal 10 first decrypts the second cipher text E2 with the transmission side public key corresponding to the transmission side secret key, and transmits the decoding result (for example, the decryption message) to the receiving side corresponding to the receiving side secret key Decrypts it with the public key. With this decryption, the issuer terminal 10 can extract the amount A in the decrypted text for the second cipher text E2, and updates the amount storage unit 12 based on the extracted amount A. Through this decryption procedure, the issuer terminal 10 can accurately grasp the amount requested by the receiving terminal 30 to the transmitting terminal 20. [ Then, the issuer terminal 10 encrypts the second cipher text E2 with the issuer secret key of the issuer terminal 10 to generate a third cipher text E3 (S20). A common factor (N) will be used when generating the third cipher text (E3).

In step S20, it is assumed that the transmission side public key and the reception side public key are generated in an odd number by the F function. That is, in order to use all kinds of identifiers as key values of the public key, it is preferable to generate the transmitting public key and the receiving public key in an odd number. The F function is a hash function or hash function that outputs an odd number for all input values.

Then, the issuer terminal 10 transmits the third cipher text E3 to the transmitting terminal 20 (S22).

The transmitting terminal 20 transmits the third cipher text E3 to the receiving terminal 30 (S24).

The receiving side terminal 30 decrypts the third cipher text E3. At this time, the receiving-side terminal 30 decrypts the third cipher text E3 with the issuing-side public key corresponding to the sending-side public key and the issuing-side private key corresponding to the sending-side private key. That is, the receiving side terminal 30 first decrypts the third cipher text E3 with the transmitting side public key corresponding to the transmitting side secret key, and sends the decryption result (e.g., decrypted message) again to the issuing side corresponding to the issuing side secret key Side public key. The receiving side terminal 30 determines whether the amount A 'and the random number R' contained in the final decoding result coincide with the amount A and the random number R used in generating the first ciphertext . If the result of the determination is affirmative, the transaction storage unit 33 is updated and the transaction is completed (S26). Here, the update of the amount storage unit 33 and the completion of the transaction may mean receiving the corresponding amount and updating the amount information of the amount storage unit 33.

In the above step S26, it is assumed that the transmitting side public key and the issuing side public key are generated in an odd number by the F function. That is, in order to use all kinds of identifiers as the key value of the public key, it is preferable that the transmitting public key and the issuing public key are generated in an odd number. The F function is a hash function or hash function that outputs an odd number for all input values.

On the other hand, if the amount A 'and the random number R' included in the decrypted result at the receiving terminal 30 do not match the amount A and the random number R used in generating the first ciphertext, You will not receive the money.

According to the embodiment of the present invention described above, the amount A to be paid at the receiving side can be specified, and a random number can be generated to start the transaction.

That is, the starting point of the transaction is not the issuer terminal 10 and the transmitting terminal 20, but the receiving terminal 30 is the starting point of the transaction and generates information for the transaction, and the issuing public key and the transmitting public key And the receiving side public key use the same common factor N, there is no need to inquire public key authentication to a server such as CA (Certification Authority) (CA) or RA (Registration Authority) It is very efficient because it can be verified immediately by the terminal.

Since the random numbers are associated with all the amounts A in a one-to-one correspondence, if the random number of the corresponding amount A is compared with the first random number generated as a result of decoding at the receiving end, This is not only straightforward, but also solves the problem of double payment.

In addition, the above-described electronic money transaction method of the present invention can be implemented as a computer-readable code on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like. The computer readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner. And, functional programs, codes and code segments for implementing the above method can be easily inferred by programmers of the technical field to which the present invention belongs.

As described above, an optimal embodiment has been disclosed in the drawings and specification. While specific terms have been employed herein, they are used for the purpose of describing the invention only and are not used to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: Issuer terminal
11: issued key storage unit
12, 33: an amount storage unit
13, 22, 34: process processor
14, 23, 35:
20: transmitting side terminal
21: Transmission key storage unit
30: Receiving terminal
31:
32: Receive key storage unit

Claims (18)

Designating an amount of electronic money to be requested by the receiving side module and generating a random number;
The receiving module generating a first ciphertext based on the amount and the random number;
The transmitting module generating a second cipher text based on the first cipher text;
The issuing side module decrypting the second cipher text with the transmitting public key and the receiving public key;
The issuer-side module generating a third ciphertext based on the second ciphertext;
The receiving module decrypting the third cipher text with a transmitting public key and a issuing public key; And
And a step in which the receiving module determines whether the result of decoding the third cipher text matches the amount and the random number,
Wherein the transmitting side public key, the issuing side public key, and the receiving side public key are generated in an odd number by an F function. The method according to claim 1,
Wherein the F function is a single function or a hash function that outputs an odd number for all input values. The method according to claim 1,
The transmitting side public key, the issuing side public key, and the receiving side public key have the same common factor N (N = p * q, p = 2p '+ 1, q = 2q' + 1 Is a prime number, and p and q are different prime numbers). The method according to claim 1,
The step of decrypting the second cipher text with the transmitting public key and the receiving public key includes:
And a step of extracting an amount corresponding to the decryption and updating the information of the amount storage unit in the issuing side module. The method according to claim 1,
And the third ciphertext is transmitted to the receiver module via the transmitter module. The method according to claim 1,
Wherein the step of determining whether the decryption result of the third cipher text matches the amount and the random number includes:
And updating the information of the amount storage unit in the receiver module based on the decrypted amount when the result of decoding the third cipher text matches the amount and the random number. . A computer-readable recording medium on which a computer program for performing the electronic money transaction method according to any one of claims 1 to 6 is recorded. A computer program stored in a computer-readable recording medium for performing the electronic money transaction method according to any one of claims 1 to 6. A trading system which is requested by the receiving side module for the electronic money issued by the issuing side module and paid by the transmitting side module,
Wherein the receiving-
A random number generator for generating a random number;
A receiving key storage unit for storing a receiving side secret key; And
Generates a ciphertext using the receiving secret key, and transmits the encrypted ciphertext to the transmitting module, and receives the final ciphertext according to the ciphertext being sequentially encrypted through the transmitting module and the issuer module And decrypting the decrypted cipher text using the transmission side public key and the issuing side public key, and determining whether the result of decoding the final cipher text matches the amount and the random number,
Wherein the transmitting side public key and the issuing side public key are generated in an odd number by an F function. The method of claim 9,
Wherein the F function is a monotone function or a hash function that outputs an odd number with respect to all input values. The method of claim 9,
The transmitting side public key and the issuing side public key have the same common factor N (N = p * q, p = 2p '+ 1, q = 2q' + 1 And q are different prime numbers). The method of claim 11,
The issuer-
Side cryptographic module decrypts the encrypted ciphertext with the transmitting-side public key and the receiving-side public key to extract the amount of the encrypted ciphertext according to the ciphertext in the receiving-side module being re-encrypted in the transmitting-side module,
The receiving side public key is generated in an odd number by an F function, and the F function is a single function or a hash function that outputs an odd number with respect to all input values,
Wherein the receiving side public key uses a common factor (N) used by the transmitting side public key and the issuing side public key. The method of claim 9,
The reception key storage unit stores,
Is located in a universal subscriber identity module (USIM) or a trust zone of the corresponding receiving-side module. A trading system which is requested by the receiving side module for the electronic money issued by the issuing side module and paid by the transmitting side module,
The issuer-
A issuing key storage unit for storing the issuing secret key; And
The first ciphertext based on the amount requested by the receiving module and the random number generated by the receiving module is encrypted with the second ciphertext in the transmitting module and the second ciphertext is received with the transmitting public key And a process processor for generating a third cipher text using the issuing secret key and transmitting the second cipher text to the receiving module via the transmitting module,
Wherein the transmission side public key and the reception side public key are generated in an odd number by an F function. 15. The method of claim 14,
Wherein the F function is a monotone function or a hash function that outputs an odd number with respect to all input values. 15. The method of claim 14,
Wherein the process processor generates and provides a common factor that can be commonly used by the transmitting module and the receiving module,
Wherein the common key and the common key are identical to each other, the common key and the common key are N = p * q, p = 2p '+ 1, q = 2q' Is a prime number, p and q are different prime numbers, and N is a common factor). 18. The method of claim 16,
Wherein the receiving module determines whether the result of decoding the third cipher text by the transmitting public key and the issuing public key matches the amount and the random number,
The issuing public key is generated in an odd number by an F function, and the F function is a single function or a hash function that outputs an odd number with respect to all input values,
Wherein the issuing-side public key uses a common factor used by the transmitting-side public key and the receiving-side public key. 15. The method of claim 14,
The issuing key storage unit stores,
And is located in a universal subscriber identity module (USIM) or a trust zone of the issuer-side module.

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