RU2656578C1 - Method for generating encryption keys - Google Patents

Abstract

FIELD: cryptography.

SUBSTANCE: invention relates to the field of information security of telecommunication systems and can be used to generate password-based encryption keys. Method for generating the encryption key is that a random number with a bit width of at least 32 bits is generated, the initial password is additionally generated in the form of a digital representation of symbolic or biometric information, and from the initial password and a random number with a bit width of at least 32 bits, a pseudo-random number is generated in the form of an array of round keys, for which they are cyclically encrypted at a given number of iterations on the cryptographic converter, after which the round keys array is checked for cryptographic strength by "strong key" criterion and the number of round keys that do not meet the "strong key" criterion and are discarded are simultaneously determined, and in the event that the number of discarded round keys does not exceed the mathematically calculated probabilistic number of such keys in the array of round keys, the received array of round keys is used as encryption keys, otherwise – either the password is modified or the random number is modified that is used to obtain a new array of round keys with their further check for cryptographic strength by the "strong key" criterion.

EFFECT: ensuring the generation of encryption keys with enhanced cryptographic stability.

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Description

The invention relates to the field of information security of telecommunication systems and can be used to generate encryption keys based on passwords.

A known method of generating encryption keys [M.A. Ivanov. Cryptography. M., KUDITS-IMAGE, 2001, p. 197-198], including the conversion of a random multi-bit binary number, called the time stamp and determined by the point in time, for example, by the time of the beginning of the communication session, according to a previously agreed cryptographic algorithm controlled by a secret key, which subscribers exchange beforehand over a secure communication channel.

The disadvantage of this method is the relatively high complexity caused by the need to transmit the secret key through a secure communication channel, which is an expensive element of secret communication systems.

There is also a method of generating encryption keys [M.A. Ivanov. Cryptography. M., KUDITS-IMAGE, 2001, p. 205] by repeatedly sequentially modifying the secret key in accordance with the one-way conversion algorithm.

The disadvantage of this method is the relatively low cryptographic strength, since when the current key is compromised, all subsequent data encryption keys are compromised.

In addition, methods are known for generating an encryption-decryption key [GOST 28147-89, British B-Grypt algorithm, US Standard DES, Japanese FEAL data encryption algorithm].

In these methods, the encryption-decryption key is generated by using a random number generator with some unpredictable factor, for example, the choice of bits from the timer, the generated numeric key is transmitted to network users and used as the base (initial value) of the pseudo-random sequence of numbers, and to encrypt the message, the output bitstream is summed modulo 2 with the source text.

However, these known methods-analogues of encryption-decryption key generation are also characterized by relatively high complexity caused by the need to transmit the secret key through a secure communication channel, which is an expensive element of secret communication systems.

,

, формируют ключи шифрования/дешифрования на приемной и передающей сторонах направления связи путем хэширования блока X₁ на передающей стороне направления связи и декодированного блока X₁ на приемной стороне направления связи.In addition to the above, there is a known method of generating an encryption key [RU 2295199, C1, H04L 9/14, 03/10/2007], according to which a random sequence is formed on the transmitting side of the communication direction in the form of three blocks X ₁ , X ₂ , X ₃ with lengths k ₁ , k ₂ , k _3, respectively, transmit it via the communication channel with errors to the receiving side of the communication direction (Y ₁ , Y ₂ , Y ₃ - received blocks), form blocks of check symbols C ₁ and C ₂ for blocks X ₁ and X _2, form a message S _{c1 + c2} by concatenating the blocks C ₁ and C _2, form authenticator w to the received message, ispol'uet yn AP-code and the block X ₃ is transmitted message S _{c1 + c2} and authenticator w over the communication channel without error on the receiving side communication destinations, on the reception side communication direction authenticate the received message S _{c1 + c2,} using AP-code and the block Y ₃ , the blocks of check symbols C ₁ and C ₂ are extracted from the received message S _{c1 + c2} , from the blocks Y ₁ , Y ₂ and blocks of check symbols C ₁ and C ₂ previously received via the error channel, decoded blocks are formed

,

form encryption / decryption keys on the receiving and transmitting sides of the communication direction by hashing the block X ₁ on the transmitting side of the communication direction and the decoded block X ₁ on the receiving side of the communication direction.

However, this method of generating the encryption-decryption key is also characterized by relatively high complexity and relatively low cryptographic strength, caused by the need to transmit data over the communication channel.

от которого содержит, по крайней мере, один простой множитель Y в виде ξ-разрядного двоичного числа, после чего генерируют произвольное многоразрядное двоичное число β и вычисляют второе многоразрядное двоичное число α открытого ключа по формуле

, для которого выполняется условие

, а для формирования образа R ключа шифрования у отправителя информации генерируют случайное σ-разрядное двоичное число W, а образ R ключа шифрования рассчитывают по формуле

, где t - показатель, предварительно заданный получателю и отправителю информации, причем для вычисления ключа шифрования К у получателя информации рассчитывают дополнительное многоразрядное двоичное число

, после чего ключ шифрования вычисляют по формуле

.The closest in technical essence to the proposed is a method of generating an encryption key [RU 2286022 C1, H04L 9/30, H04K 1/00, G09C 1/06, 10/20/2006], which consists in the fact that the recipient of the information form the public key in the form the first p and second α multi-bit binary numbers, transmit it to the sender of information, which form the image of the encryption key in the form of a multi-bit binary number R and transmit it to the recipient of information, where they calculate the encryption key in the form of a multi-bit binary number K, in this case, to form open to In the case of the recipient of information, the first multi-bit binary number p of the public key is calculated, the Euler function

from which it contains at least one prime factor Y in the form of an ξ-bit binary number, after which an arbitrary multi-bit binary number β is generated and the second multi-bit binary number α of the public key is calculated by the formula

for which the condition is satisfied

and to generate an image R of the encryption key, a random σ-bit binary number W is generated from the sender of information, and the image R of the encryption key is calculated by the formula

, where t is an indicator previously set to the recipient and sender of information, and to calculate the encryption key K, an additional multi-bit binary number is calculated from the recipient of information

after which the encryption key is calculated by the formula

.

The features of the method are that a simple factor Y is selected with a bit depth ξ in the range 64≤ξ≤256 bits, a bit capacity σ of a random multi-bit binary number w is selected from the condition σ≤ξ, the indicator t predefined for the receiver and sender of information is selected from the condition 2≤t ≤256, to calculate the first multi-bit binary number p of the public key, the first auxiliary prime factor in the form of a multi-bit binary number m is generated, a simple factor Y in the form of an ξ-bit binary number is generated and supplement noe even multi-digit random binary number and then calculating a second auxiliary prime factor n in the form of a random multi-bit binary number n = γ u + 1, and the first multi-digit binary number of the public key p is calculated as the product of the first and second m n auxiliary prime factors.

The disadvantage of the closest technical solution is the relatively narrow scope of its application, since it allows you to generate relatively low encryption keys encryption keys. This is because the complexity of computing keys from a password is determined by a fixed number of cryptographic conversion cycles, and the keys themselves are pseudo-random numbers. At the same time, there are no guarantees that the keys do not have hidden relationships that emerged from the algorithmic properties of the procedure for generating them, and when generating encryption keys, they are not checked for cryptographic strength, which can lead to cracking of encrypted information.

The problem that is solved in the proposed invention is the development of a method that allows you to generate encryption keys, characterized by increased cryptographic strength.

The required technical result is to expand the scope of the method in order to enable the formation of encryption keys with increased cryptographic strength.

The problem is solved, and the desired technical result is achieved by the fact that, in the method, which consists in generating a random number with a bit capacity of at least 32 bits, according to the invention, additionally generate the original password in the form of a digital representation of symbolic or biometric information, and from the original a password and a random number with a bit capacity of at least 32 bits form a pseudo-random number in the form of an array of round keys, for which they are cyclically encrypted at a given number of iterations on the cryptoconverter, after hours its array of round keys is checked for cryptographic strength using the “strong key” criterion, and at the same time, the number of round keys that do not meet the “strong key” criterion is determined and discarded, if the number of rejected round keys does not exceed the mathematically calculated probability number of such keys in the array round keys, then the resulting array of round keys is used in the form of encryption keys, otherwise - either modify the password or modify the random number that is used to receive tions of a new array of round keys with subsequent test of cryptographic criterion "strong key."

The proposed method for generating encryption keys is implemented as follows.

A password is supplied to the input of the cryptographic converter (for example, made in accordance with GOST R 34.13-2015), which is, in particular, a digital representation of either symbolic information or other, for example, biometric, and a random number received from a random number generator with a bit width excluding the ability to iterate over all options in a reasonable period, usually at least 4 bytes (32 bits). The password and a random number are cyclically encrypted on the cryptocurrency converter for a given number of cycles, for example, “gamma with data feedback” according to GOST R 34.13-2015 is calculated at a given number of iterations, after which the last received value is used as a pseudo-random number in the form of an array of round keys.

The resulting array of round keys is checked for cryptographic strength according to the "strong key" criterion. Moreover, the pseudo-random number consists of an array of round keys, usually from 8-16 “round keys”. For example, a 256-bit pseudo-random number consists of 8 32-bit round keys. Round keys verify the “strong” key criterion. The criterion may be the equality of the number of numbers “0” and “1” in the binary representation of the round key, the absence of the same groups of bits and other specific information, and to check the independence of the bits of the round key, a series criterion. The selection of criteria is determined by the requirements for strong keys in a particular cryptographic scheme.

If the round keys satisfy the requirement of the “strong key” criterion, then they are preliminarily entered into the storage area of the encryption keys. In parallel with this process, the number of unsuccessful cycles is being counted when the round keys do not satisfy the “strong key” criterion. After checking the entire array of the obtained round keys, the number of unsuccessful cycles is compared with the mathematically calculated admissible probabilistic number on a sequence of random numbers. If the numbers of unsuccessful cycles satisfy the requirements of a mathematically calculated probabilistic number, then non-discarded round keys are considered to be obtained in the process of sampling from a truly random sequence and are accepted as encryption keys that meet the “strong key” criterion. Otherwise, the round key array is considered to not meet this criterion, and either a password change or a random number modification is required, which are used to obtain the round key array and the procedure for checking it using the strong key criterion is repeated.

Claims (1)

A method of generating encryption keys, which consists in generating a random number with a bit depth of at least 32 bits, characterized in that it additionally generates an initial password in the form of a digital representation of symbolic or biometric information, and from a source password and a random number with a bit capacity of at least 32 bits form a pseudo-random number in the form of an array of round keys, for which they are cyclically encrypted at a given number of iterations on the cryptoconverter, after which the array of round keys is checked for cryptographic strength by the “strong key” criterion and at the same time determine the number of round keys that do not meet the “strong key” criterion and are discarded, and if the number of discarded round keys does not exceed the mathematically calculated probabilistic number of such keys in the array of round keys, then the resulting array of round keys the keys are used in the form of encryption keys; otherwise, they either modify the password or modify the random number that they use to obtain a new array of round keys with their subsequent verification rkoy on cryptographic criterion "strong key."