KR100497130B1 - Encryption method of binary code information - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to communications and computer engineering, and in particular to encryption methods and equipment for encrypting arithmetic data. The present invention comprises generating a data block of K or less including elements of a binary information code of P≥1, and converting the data block under the control of an encryption key. A novel element of the system is that a binary vector of D≥1 is additionally generated so that the data block is connected to a binary vector and a corresponding element of a binary information code. The binary vector is randomly or pseudo-randomly generated, and binary information is generated. It is associated with the corresponding element of the code, and that connection is the basis of the private key.

Description

Encryption method of binary code information

The present invention relates to the field of communications and computer engineering. More specifically, it relates to a method and apparatus for encrypting data.

The concepts used to explain the present invention are as follows.

The private key refers to binary information that only the authenticated user knows.

An encrypter is a combination of the basic processes of converting input data using a secret key that can be performed in the form of a computer program or as an independent unit.

Encryption is a process of converting digital information under the control of a secret key, and converts the original data into an encrypted sentence represented by a pseudo-random string that cannot be extracted from it without acquiring the key.

Decryption is the reverse process of encryption where the operator knows the encryption key and extracts the original information from the encrypted statement.

Binary vector means a specific on-off bit string such as, for example, noise or pseudo signals present on a communication link. In the present invention, a binary vector means a command bit string that is not converted into a desired signal or information by a receiver.

The pseudo random law for forming a binary vector refers to a law for generating an extended bit string based on an initial parameter and dividing the bit string into elements of a required size. Secret key or random number may be used as the first parameter. If the value is unknown, the output will be a random signal that is virtually indistinguishable.

Cryptography is a technique for calculating a secret key to solve encrypted information without authentication, or a method of obtaining such information without calculating a secret key.

Cryptographic resistance is a measure of the likelihood of data protection, and refers to the labor intensity given the number of basic operations that must be performed to return information from the ciphertext in the context of the operator acquiring the conversion algorithm without a secret key.

Many methods are known for encrypting data. For example, Cypher RC5 (R. Rivest, RC5 encryption algorithms, rapid software encryption, 2nd International Workshop (Ruven, Belgium, Dec. 14-16, 1994), Computer Science Lecture Notes v.1008, Springer-Verlag , 1995, pp86-96). According to this conventional method, the encryption of the data block is performed by a secret key, the data block is divided into lower data blocks, selectively alternated by a cyclic shift operation, and finally the modular 2 sum and the modular 2 of the current block. ³² Perform the sum. This block method is performed by an encryptor in the form of a computer program to enable a high encryption rate.

However, the above method can be used for differential and linear cryptography (Kaliski BS, Yin YL, RC5 cryptographic algorithms. Differential and linear cryptography. It doesn't show enough resistance, because such an encryption technique could allow an attacker to encrypt a specially selected text.

The method most similar to the patented block encryption method is described in US standard DES (US Standards, Data Encryption Standard, Federal Information Processing Standards Publication 46, 1997. 1). The method comprises the steps of forming a private key of a particular length, dividing the input information expressed in the form of a binary code into elements of 64-bit, generating the 64-bit data block, and controlling the blocks under the control of the secret key. It consists of a step of converting. Prior to conversion, each data block is divided into two 32-bit sub-blocks L and R, which are handled alternately during 16 similar rounds of conversion. A single transform round consists of a modular two sum that produces a substitution, exchange and subblock R. Each round ends by exchanging lower blocks R and L. The block ciphering method described above has a high conversion rate when performed by a special electronic circuit.

Unfortunately, the drawbacks that make up this method are problems when using this method, and it is possible to effectively apply various encryption techniques based on a specially selected input block of the original text. This drawback is due to the fact that in such cryptographic analysis, the analyst performed by the development of the statistical properties of the encryption algorithm is able to select the initial input text.

Accordingly, an object of the present invention is to provide a method for encrypting binary coded information by a given fixed private key, and to provide an encryption method for converting the original text into encrypted text of an undetermined structure, thereby providing a statistical method of encryption algorithm. It makes the detection of characteristics more difficult and increases the resistance of cryptographic analysis based on the selected original text.

1 is a schematic diagram showing a process of encrypting an original text P according to the present invention.

Fig. 2 is a block diagram showing the decryption process of encrypted text C.

3 shows the binary information code element P ₁ . P ₂ , ... P _i ... and the resulting binary vectors r ₁ , r ₂ , ... r _i , ... shows the division process.

4 schematically shows an input data block removed by connecting a binary vector to an element of a binary information code.

Fig. 5 is an encryption block diagram related to the second embodiment.

The problem consists of generating a secret key, generating a data block of K or less including elements of a binary information code of P≥1, converting the data block under the control of a secret key, and D≥1. The binary vector of is further generated, and the data blocks are generated by connecting the binary vector to the corresponding element of the binary information code.

The definition of blocks of text encrypted through such an operation depends not only on the structure of the secret key and binary information code element, but also on the structure of the binary vector, so that the definition of the encrypted text block is based on the given original text and the secret adopted. It is no longer fixed by the key. As a result, it is more difficult to extract statistical characteristics of the encryption algorithm, and the resistance of cryptographic analysis performed based on the selected original text is increased.

Another novel feature of the present invention is that these vectors are randomly generated. This enables random modulation of the encrypted text block and improves the resistance of cryptographic analysis by known methods.

Another feature is that binary vectors are pseudo-randomly generated and can be performed on a PC by generating a random number by software using the patented method without using any additional electronic circuitry.

Another novel feature is that binary vectors are associated with elements of the corresponding binary information code based on the secret key. This method introduces additional uncertainty in the creation of the data block, thereby increasing the resistance of the cryptographic system.

The present invention is easily understood by the general diagram of cryptographic transformation of the data block by the present invention shown in FIG. In Fig. 1, RNG is a random number generator, R is a random binary vector, P is an element of transformed binary information, E is an encryption unit, K is a secret key, C is an encrypted text output, and [│] is It is a symbol of linking action.

The element of binary information in the encryption system is connected to a randomly generated binary vector R and fed to the input of the encryption element E to produce a data block B = R | P that produces encrypted text C.

In the context of the present invention, the block generating the binary vector constitutes a part of the encryptor and is therefore not replaced, and the encryption algorithm is not altered by reverse analysis in the course of cryptographic analysis performed on the basis of the selected text. These provisions are typically required in conventional known encryptors. The structure of the binary vector changes in an unpredictable way in the encryption process, which is performed by a random number generator. Thus, an encrypted data block obtained by linking a binary vector to an input block cannot be previously selected or known. Therefore, there is almost no obstacle due to the infringement performed based on the selected initial text.

The authenticated user knows the encryption key, and he can restore the structure and input block of the binary vector using the appropriate algorithm. If the user discards only the binary vector, it does not contain any information sent, and he can completely recover what was intended for him.

2 is a block diagram showing a decoding process related to the present invention. The block of encrypted text is sent to the decoder D, and using the input secret key K, it is possible to recover the value of the data block B = R│P. The restored binary vector R, previously written and used in the encryption process, is erased bit by bit by modular 2 summation between R and the new random number output from the random number generator in the encryption system.

Random number generators of binary vectors can be performed, for example, by measuring the signal of a noise converter, which is a stochastic physics process or in many cases a specially designed electronic circuit. According to another embodiment, instead of the random number generator, a pseudo random number generator capable of obtaining a pseudo random number sequence of a desired size may be used by supplying a randomly selected binary number. Much is known about pseudorandom number generators. An example is (B. Schneier, Applied Cryptography, 2nd Edition, John Wiley & Sons, Inc., New York, 1966, pp416-418) if we elapsed between consecutive key strokes as an initial random number, for example. The use of such a generator makes it possible to realize the method proposed by the software if taking the value of the time interval.

In order to encrypt the lower block, the method described above or an approximation to the present invention can be used, and a block as described in US Patent No. 5,003, 596 (MCWood, Method for Encrypting and Transmitting Electronic Digital Data, March 26, 1991). You can also use an encryption method.

The technical flexibility of the present invention will be demonstrated by the following embodiments. For the sake of understanding, the embodiments will be given in the form of an algorithm consisting of logical records of a continuous process performing a particular embodiment of the proposed block encryption method.

Example 1

This embodiment shows a method of encrypting information represented in the form of binary code divided into 32 bit elements. Unit E guarantees the encryption performance of the 64-bit data block according to the prior art described above.

Algorithm 1: 32-bit block encryptor

1. Take the next 32-bit element of binary code information P. Generate a 32-bit random vector R and a data block B = R | (The symbol | is a sequential symbol.)

2. Encrypt the 64-bit data block using the prior art.

Example 2

This embodiment shows a method of encrypting information represented in the form of binary code subdivided into 12-bit elements. A known method of encrypting a 64-bit block B (B = X | Y) can be used. The encryption function is designated E (B) when encrypting block B, and is converted by the B ← E (B) rule. ← means assignment action. The following algorithm is used for the description of Example 2.

Algorithm 2: 48-bit block encryptor

1. Generate an encryption key.

2. Take the next 12 bit elements p ₁ , p ₂ , p ₃ and p ₄ of the binary information code, generate four random 20-bit binary vectors v ₁ , v ₂ , v ₃ and v _4, and create a data block P _{= p 1 │v 1 │p 2 │v} 2 │p 3 │v 3 │p generates ₄ │v _4.

3. Divide the data block P into two subblocks: P = X│Y, X = p ₁ │v ₁ │p ₂ │v ₂ , Y = p ₃ │v ₃ │p ₄ │v ₄

4. Convert the lower block X. X ← E (X)

5. Replace lower block X with lower block Y: Y: Y ⁺ X, ⁺ means modular 2 sum in bits.

6. Convert the lower block. Y ← E (Y)

7. Replace lower block Y with lower block X. X: X ← X ⁺ Y

8. Convert the lower block X. X: X ← E (X)

9. Replace lower block X with lower block Y. Y: Y ← Y ⁺ X

10. Convert lower block Y. Y: Y ← E (Y)

11. Replace lower block Y with lower block X. X: X ← X ⁺ Y

12. Send block X│Y to the output block of encrypted text.

Embodiment 2 is shown in Figs. In Figure 3, block 1 is a binary information code subdivided into 12-bit elements, and block 2 is a generated 20-bit vector sequence. 4 shows the generated data block definition. An overview of the conversion is shown in FIG. 5, where block E represents the encryption process according to the prior art.

Example 3

This embodiment shows the application of a secret key to a method of generating a 1024 byte data block B using a 32 bit element of a binary information code and a 32 bit random binary vector. The encryption process uses an existing encryptor "crab". (Kaliski BS, Robshaw MJB Rapid Block Encryptor Proposal, Rapid Software Encryption, Minutes of the Cambridge Safety Workshop, Computer Science Lectures, v.809, Springer-Verlag, 1994, pp.26-39, B.Schneier, Applied Cryptography, 2 edition, John Wiley & Sons, reference Inc., New York, 1966, pp.342-344) the cryptographic groups the 32-bit sub-block _{B 0, B 1, B 2} , ..., 1024-byte data blocks represented by the B ₂₅₅ It is used to convert the code, using a secret key in the form of a conversion table and 2048 subkeys Q ₀ , Q ₁ , Q ₂ , ..., Q ₂₀₄₇ with a 32-bit length. E is defined as the encryption function defined by the "Crab" encryptor. The following algorithm describes the procedure associated with Example 3.

Algorithm 3: 512 byte probabilistic encryptor

Input: 32-bit element of binary information code. 512-byte element of binary information code in the form p ₀ , p ₁ , p ₂ , ..., p ₁₂₇ .

Generate 128 random 32-bit binary vectors r ₀ , r ₁ , r ₂ , ..., r ₁₂₇ .

2. Integrate 32-bit binary vectors and 32-bit elements of binary information code into intermediate blocks.

(t ₀ │t ₁ │t ₂ │ ... │ t ₂₅₅ )

(t ₀ │t ₁ │t ₂ │ ... │t ₁₂₇ ) = (r ₀ │r ₁ │r ₂ │ ... │ r ₁₂₇ )

(t ₁₂₈ │t ₁₂₉ │t ₁₃₀ │ ... │t ₂₅₅ ) = (p ₀ │p ₁ │p ₂ │ ... │ p ₁₂₇ )

3. Using the following subkeys Q ₀ , Q ₁ , Q ₂ , Q ₃ and Q ₄ , the parameters u ₁ = Q ₀ mod 256, u ₂ = Q ₁ mod 256, u ₃ = Q ₂ mod 256, s (1) = Q ₃ mod 8, S (2) = Q ₄ mod 8

4. Set the initial counter value i to 0 and the 32-bit variable b ₀ = b ₁ = b ₂ = ... = b ₂₅₅ = 0.

5. Index h = [(u ₁ ⁺ i) ^{<<< s (1)} + u ₂ ] ^{<<< s (2) +} u ₃

6. Assign the value t _h to the variable b _i . : b _i ← t _h

7. If i ≠ 256, increase i by 1 and perform item 5. : i ← i + 1

8. Integrate the variable b _i into a 1024 byte data block. : B = b ₀ │b ₁ │b ₂ │ ... │b ₂₅₅

9. Encrypt block B using the encryptor "Crab". B: C = E (B), E is an encryption function of the encryptor.

Output: 1024-byte data block in encrypted text C

Items 2, 3, ..., 7 represent the process of linking elements of the binary information code to a binary vector based on the subkeys Q ₀ , Q ₁ , Q ₂ , Q ₃ , Q ₄ more precisely.

As described in the above embodiments, the block encryption method of the present invention is technically flexible and can achieve the object of pursuit well.

The above embodiments can be easily performed with a personal computer and can create a software encryption module with high resistance to infringement made using the initial text selected thereon.

By the above embodiments, the encryption method of the digital data of the present invention has been proved to be technically flexible, and the object to be pursued can be achieved.

The present invention can be performed by a PC, presenting the possibility of replacing expensive and complicated encryption equipment with a personal computer equipped with a software system capable of creating the basis of a high speed software encryption module and enabling rapid encryption.

Claims (4)

Forming a secret key; Forming one or more data blocks containing elements of a binary information code whose number is P≥1; Converting the data block under the control of a secret key; A binary code D, independent of the elements of the binary information code, wherein D> 1 is further generated and the data blocks are formed by connecting the binary vectors with corresponding elements of the binary information code How do you encrypt information? The method of claim 1, wherein the binary vector is generated randomly. 2. The method of claim 1 wherein the binary vector is generated as a pseudo random vector. 2. The method of claim 1 wherein the binary vector is associated with corresponding elements of a binary information code based on a secret key.