JPH10153955A - Ciphering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the ciphering device in which the degree of ciphering is increased without increasing the processing time by deforming the structure of a ciphering processing section or a decording processing section based on prescribed information. SOLUTION: A deforming section 20 consists of a ciphering function deforming section 20a and a ciphering function deforming information computing section 20b. In the example in which a common key X is used, an exclusive OR is taken for a corresponding stage information X (an arbitrary Xth stage) of a stirring processing section 3, which conducts a tracing in the section 20b and the key X for every bit and the result is set as Z. Define low-order 24 bits of Z as G and compute (i) which is computed by dividing Z with a number (n), that is the total number of stages (16 stages), obtaining a remainder Y of the division above and adding 1 to the remainder Y. Having received X, (i) and G, the section 20a is deformed and the result is thrown into an Xth stage stirring processing section 3X. In other words, ciphering function sections 41 to 4n are not in a fixed form and are deformed. A decoding function section of each stage used in a decoding is deformed in a same order as during a ciphering and is thrown in.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encryption device, and more particularly, to an encryption device capable of achieving high strength in a common key block encryption system.

[0002]

2. Description of the Related Art Conventionally, in communications in the commercial and financial fields such as e-commerce and electronic money, in various service fields such as a contactless commuter pass system, and in the information field such as e-mail on the Internet, confidentiality of communication contents and Encryption is used for authentication of a communication partner.

[0003] There are various encryption methods, but a sender and a receiver share a common key, encrypt plaintext using the common key, and further use the common key to encrypt plaintext. There are a DES cipher that decrypts and restores a plaintext, and a common key block cipher represented by the FEAL cipher.

FIG. 11 is a schematic configuration diagram of a typical encryption device for implementing the above common key block encryption method.
In this figure, [] indicates a decryption step, but the encryption will be described first.

In a plaintext block 1 formed by blocking a predetermined plaintext to be communicated into a predetermined number of bits (for example, 64 bits), the initial transposition unit 2 replaces the bit positions in accordance with a predetermined rule. Generated in a plaintext block with a new arrangement.

[0006] The plaintext block generated by the initial transposition unit 2 is divided into right and left, that is, divided into half the number of bits of the plaintext block (32 bits in the above example), and the right conversion process statement R0 is divided into two. And a left conversion process sentence L0. These process sentences R0 and L0 are configured to be input to the stirring processing unit 3.

[0007] The stirring section 3 has a plurality of stages (for example, 16 stages).
, That is, the first-stage agitation processing unit 31 to the n-th-stage agitation processing unit 3n, and the respective stage agitation processing units 31 to 3n include encryption function units 41 to 4n.
And exclusive OR sections 51 to 5n.

[0008] Each of the encryption function units 41 to 4n uses the fixed position intermediate keys (corresponding to the intermediate keys of the present invention) K1 to Kn obtained from the intermediate key generation unit 10 shown in FIG. It is processed.

The intermediate key generation unit 10 performs a predetermined process on a common key K consisting of predetermined bits (for example, 56 bits) in a key scheduling unit 10a, and outputs a fixed position consisting of a predetermined number of bits (for example, 48 bits). Intermediate keys K1 to Kn
Is configured to generate

[0010] Of the encryption function units 41 to 4n, an encryption function unit of an arbitrary stage (hereinafter referred to as an i-th encryption function unit 4
i. ) Will be described with reference to FIG.

The right conversion process statement Ri- of the i-th stage stirring processing unit 3i.
1 is linearly processed by the linear conversion unit 4A so as to have a predetermined number of bits (for example, 48 bits), and then, in the exclusive OR unit 4B, the i-th mixing processing unit obtained from the intermediate key generation unit 10 Exclusive OR processing is performed with the fixed position intermediate key Ki for 3i.

After this exclusive OR processing is performed, the data is divided into units of a fixed number of bits (in the above example, 4 units).
Each of the units is input to the corresponding non-linear processing box 4C1 to 4Cm, and each unit is converted into another fixed number of bits (for example, 8 bits of 4 bits).
)) Is nonlinearly processed. The data subjected to the non-linear processing in each of the non-linear processing boxes 4C1 to 4Cm is subjected to linear processing in the linear conversion section 4D to generate an encryption function output sentence Bi. In the following, the non-linear processing box 4C1
1, 4C2 will be described as S2.

The generated encrypted function output sentence Bi is
The exclusive OR unit 5i of the stage agitation processing unit 3i performs an exclusive OR operation with the left conversion process statement Li-1.

The same processing as that of the above-mentioned i-th stirring processing section 3i is performed from the first-stage stirring processing section 31 to the n-th stirring processing section 3i.
n, and the right conversion process sentence Rn and the left conversion process sentence Ln from the n-th stage agitation processing unit 3n at the last stage are transposed by the inverse initial transposition unit 6 that performs the reverse transposition process of the initial transposition unit 2. Thus, the encrypted ciphertext block 7 is generated.

The ciphertext block 7 received by the receiver is restored to a plaintext block by a method reverse to the above-mentioned encryption, that is, by using the steps indicated by [] in FIG. 11 and the stationary intermediate keys Kn to K1. Is done. Therefore, the encryption function units 41 to 4n in FIG. 8 become decryption function units 41 to 4n at the time of decryption.

[0016]

However, the above-mentioned conventional encryption device of the common key block cipher system has advantages such as a high encryption processing speed. However, in recent years, the computer performance has been dramatically improved and the decryption has been performed. There is a problem that the encryption strength has been relatively reduced with the advance of technology.

In order to solve such a problem, it is conceivable to increase the number of stages of the stirring processing unit, increase the number of bits of the common key, or take a chain between blocks. Each of these raises a new problem of increasing the processing time.

In the above-mentioned conventional encryption device of the common key block system, as shown in FIG. 13, since the configuration of the encryption function section of each stage is the same for each stage,
This includes the risk of being easily deciphered by a selective plaintext attack or the like.

The present invention has been made in order to solve the above-mentioned drawbacks, and an object of the present invention is to provide an encryption device capable of increasing the encryption strength without increasing the processing time. is there.

[0020]

In order to achieve the above object, a cryptographic apparatus according to the present invention converts a block-shaped plaintext or ciphertext consisting of a predetermined number of bits into a plurality of predetermined plaintexts or ciphertexts generated from a common key. In an encryption device of a common key block cipher system, in which an intermediate key is input to a predetermined plurality of stages of encryption processing units or decryption processing units to perform encryption or decryption, the encryption processing unit or the decryption processing unit Is provided with a deforming means for deforming the structure based on predetermined information. The modification means is based on the information of the common key. The deforming means is based on the information on the generated intermediate key. The modification means is based on information of a right conversion process statement of the encryption processing unit or the decryption processing unit. The modification means is based on the information on the common key and the information on the generated intermediate key. The modification means is based on information on the common key and information on a right conversion process statement of the encryption processing unit or the decryption processing unit. The deforming means is based on information on the generated intermediate key and information on a right conversion process statement of the encryption processing unit or the decryption processing unit. The deforming means is based on information on the common key, information on the generated intermediate key, and information on a right conversion process statement of the encryption processing unit or the decryption processing unit.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an encryption device according to an embodiment.

The same reference numerals are used for the same components as those in FIGS. 11 to 13 of the related art, and the description of these components will be duplicated.

In FIG. 1, reference numeral 20 denotes a transformation unit, which comprises an encryption function transformation unit 20a and an encryption function transformation information calculation unit 20b. The encryption function transforming unit 20a performs each of the encryption function units 4 based on the result of the encryption function transformation information computing unit 20b performing a predetermined computation process based on the information of the common key K.
The contents of the structures 1 to 4n can be modified.

Before describing the operation of the transformation unit 20, a description will be given with reference to FIGS. 13 and 2 to 4 in order to facilitate understanding of the modification of the structure of the encryption processing units 41 to 4n of the present invention. . For the sake of simplicity, one plaintext block is 64 bits (FIG.
The numbers in parentheses indicate the number of bits. FIG.
12 are the same. ), And the ciphertext block is also 64 bits, so the right half of the right conversion process sentence Ri-1 (i represents the i-th stage) is 32 bits, and the left half of the left conversion process sentence Li-1 (i Represents the i-th stage), the common key K has 32 bits except for the parity bit, and the fixed-position intermediate key Ki (i represents the i-th) has 48 bits. Each of the intermediate keys K1 to Kn to be input is also 48 bits, and each of the encryption function units 41 to 4n.
, The input side of the linear conversion unit 4A is 32 bits, and the output side is enlarged and transposed to 48 bits.
The number of Sm is eight, that is, m = 8, and each of the nonlinear processing boxes S1 to Sm receives 6 bits and has a nonlinear relationship.
Output the bit, and output the encryption function output statement Bi.
(I represents the i-th stage) is 32 bits, and the total number n of the stirring sections 3 is 16 stages. In the deforming section 20, any one or two or more of the modifications described below are mixed, and there are many types of the modifications. Therefore, the types of the modifications of the present invention are as follows. Is not limited to the description.

The basic form of each of the encryption function units 41 to 4n has the conventional structure (configuration) shown in FIG.
A first modification will be described. In the first example, as shown in FIG. 2, non-linear processing boxes S1 to Sm are selected.

The algorithm for this selection is G (one of G), which is one of the deformation information passed from the encryption function deformation information calculation unit 20b.
The four bits are divided into eight pieces of three bits each. The leftmost three bits are the first, and the rightmost three bits are the eighth. Next, 1 is added to the numerical value represented by each 3 bits to obtain a new numerical value. Further, the nonlinear processing boxes indicated by the new numerical values are selected and placed at the corresponding positions. For example, if the first new numerical value is j, the non-linear processing box Sj is brought to the first (the leftmost in FIG. 13). The encrypted function unit modified in this way is used in the agitation processing unit 3.

In a second modification, as shown in FIG. 3, the non-linear processing boxes S1 to Sm are rearranged. First, the rearrangement algorithm shown in FIG. 3A is based on i (one of which is described later in detail) which is one of the deformation information passed from the encryption function deformation information calculation unit 20b. In addition, this shows a case where i is an odd number, and the positions of the non-linear processing boxes S1 to Sm are, in order from the left side (that is, from the first), Si mod 8+
1, S (i + 2) mod 8 + 1, S (i + 4) mod 8+
1, S (i + 6) mod 8 + 1, S (i + 1) mod 8
+ 1, S (i + 3) mod 8 + 1, S (i + 5) mod
8 + 1, S (i + 7) mod 8 + 1. Here, i mod 8 + 1 is obtained by adding 1 to a remainder obtained by dividing i by 8.

FIG. 3B shows a case where i is an even number, and the positions of the non-linear processing boxes S1 to Sm are Si mod 8 + 1, S (i +
4) mod 8 + 1, S (i + 3) mod 8 + 1, S (i
+7) mod 8 + 1, S (i + 2) mod 8 + 1, S
(I + 5) mod 8 + 1, S (i + 6) mod 8 + 1,
This is the position of S (i + 1) mod 8 + 1. The encrypted function unit modified in this way is used in the agitation processing unit 3.

A third modification is a non-linear processing box S
The multipass / rotation of 1 to Sm is performed. This multi-pass / rotate algorithm is shown in FIG.
As shown in (1), the upper limit of the number of multiple passes (initial value 0 by the counter T1) of the non-linear processing boxes S1 to Sm is previously set to q. And this time, if q = 2,
Upon receiving the processing in the non-linear processing box, the counter T2 is incremented. If T <q, the enlarging / rotating processing is performed in the enlarging / rotating processing section 4C ', and the processing in the non-linear processing box is performed again. This process is repeated until T ≧ q is reached.

As shown in FIG. 4 (b), the processing of the enlargement / rotation processing unit 4C 'is performed by comparing the upper (left) 2 bit odd parity of the output 4 bits of each nonlinear processing box 4C. The even parity of the lower (right) 2 bits is provided at the upper position and is provided at the lower position, each having 6 bits, and 8 bits are collected to be 48 bits. Of the modification information passed from the encryption function modification information calculation unit 20b, Rotate right by i bits based on one i. The encrypted function unit modified in this way is used in the agitation processing unit 3.

Now, an example in which the operation of the transformation unit 20 uses the common key K will be described with reference to FIG. 1. First, the stirring processing unit 3 traced in the encryption function transformation information calculation unit 20b will be described. The exclusive OR for each bit of the corresponding stage information X (representing an arbitrary Xth stage) and the common key K is taken as Z. The lower 24 bits of Z are defined as G, and a value i obtained by adding 1 to a remainder Y obtained by dividing Z by the total number of stages n (16 stages) is calculated. That is, i = 1 + Y = 1 + (XORK) mod n.

Next, the X, i, and G are passed to the encryption function transforming section 20a, and the encryption function transforming section 20a transforms the encryption function section and inputs it to the X-stage agitation processing section 3X. In a specific numerical example, now K = 00000000000
00003A (hexadecimal notation), X = 000 in the first stage
When calculating the case of 000000000001 (upper-level extension, hexadecimal representation), i = 12 and G = 00003B (hexadecimal representation).

Various types of deformation can be used, such as selecting the above-mentioned nonlinear processing box, rearranging the nonlinear processing box, and performing multi-pass / rotation of the nonlinear processing box. When performing a modification for selecting S1 to Sm, the arrangement of the non-linear processing boxes S1 to Sm by G is S1, S1.
, S 1, S 1, S 1, S 1, S 8, S 4, and the modified encryption function section is input to the first-stage agitation processing section 31. In the following, the second and subsequent stirring processing sections 32-
3n is similarly calculated, deformed and input.

As described above, each of the encryption function units 41 to 4n
Is not fixed but deformed based on the information of the common key K, so that the encryption strength can be increased.

FIG. 5 shows an encryption function modification information calculation section 20b.
Is a fixed-position intermediate key (corresponding to the generated intermediate key of the present invention) K
The encryption function transformation unit 20a is operated based on the information of 1 to Kn.

An example of the operation of the transformation unit 20 will be described. First, it is assumed that the corresponding stage information X (representing an arbitrary X-th stage) of the agitation processing unit 3 traced in the encryption function transformation information calculation unit 20b. A bitwise exclusive OR with a position intermediate key KX (representing the X-th fixed position intermediate key and 49 bits or more is all 0) is taken as Z, and the lower 24 bits of Z are taken as G and I do. In addition, i is calculated by adding 1 to a remainder Y obtained by dividing this Z by the total number n of stages.
That is, i = 1 + Y = (X xor KX) mod n.

Next, the X, i, and G are passed to the encryption function deforming section 20a, and the encryption function deforming section 20a deforms the encryption function section and inputs it to the X-stage agitation processing section 3X. In a concrete numerical example, K1 = 000000
0000016 (upper-level extension, hexadecimal expression), and X = 000000000000001 (upper-level extension, 16
Calculate the case of (hexadecimal expression), i = 8, G = 0000017
(Hexadecimal representation). Here, as described above, when performing a modification for rearranging the non-linear processing boxes S1 to Sm, the arrangement is as follows: S1, S5, S4, S8, S3, S3
6, S7 and S2. Hereinafter, the calculation and deformation are similarly applied to the second and subsequent stages, and then input.

As described above, each of the encryption function units 41 to 4n
Is input based on the information of the fixed position intermediate keys K1 to Kn without being input in a fixed form, so that the encryption strength can be increased.

FIG. 6 shows an encryption function modification information calculation section 20b.
Operates the encryption function transformation unit 20a based on the information of the right conversion process statements R0 to Rn-1 of the stirring processing unit 3.

An example of the operation of the transformation unit 20 will be described. First, the corresponding stage information X (representing an arbitrary Xth stage) of the agitation processing unit 3 traced in the encryption function transformation information operation unit 20b is described. , The lower 24 bits of the right conversion process sentence RX (input to the encryption function unit at the X-th stage) are G,
The value i is obtained by adding 1 to a numerical value rX in which 5 bits or more are all 0 while leaving the lower 4 bits of the right conversion process sentence RX as it is. That is, i = rX + 1.

Next, the X, i, and G are transferred to the encryption function transformation unit 20a, which transforms the encryption function unit and inputs it to the X-stage agitation processing unit 3X. In a specific numerical example, R0 = 000001F
6 (hexadecimal notation), and when the first stage is calculated, i =
7, G = 0001F6 (hexadecimal notation).

Here, the multipass / rotate deformation of the non-linear processing boxes S1 to Sm will be described. First, upon receiving the first processing in the nonlinear processing box, among the four bits output from each of the nonlinear processing boxes S1 to Sm, the upper (left) two-bit odd parity is provided in the upper part, and the lower (right) two bits are provided. Are provided in the lower order, each having 6 bits, each of which has 6 bits, and 8 bits are collected into 48 bits. Based on i, which is one of the modification information passed from the encryption function modification information calculation unit 20b, i = It is rotated right by 7 bits. Then, since q = 2, it undergoes another processing in the nonlinear processing box. The transformed encryption function unit is input to the first-stage stirring processing unit 31. Hereinafter, the second and subsequent stages are similarly calculated, deformed and input.

As described above, each of the encryption function units 41 to 4n
Is not fixed, but is transformed on the basis of the information of the right conversion process statements R0 to Rn-1, so that the encryption strength can be increased.

FIG. 7 shows an encryption function modification information calculation section 20b.
Operates the encryption function transformation unit 20a based on the information of the common key K and the fixed position intermediate keys K1 to Kn.

An example of the operation of the transformation unit 20 will be described. First, the correspondence information X (representing an arbitrary X-th stage) of the agitation processing unit 3 traced in the encryption function transformation information calculation unit 20b is described. The exclusive OR for each bit of the common key K and the fixed-position intermediate key KX (representing the X-th fixed-position intermediate key, and 49 bits or more are all 0) is taken, and it is set as Z. Let 24 bits be G. Also, this Z
Is calculated by adding 1 to a remainder Y obtained by dividing the total number of steps by n. That is, i = 1 + Y = 1 + (K xor KX) mod n.

Next, the X, i, and G are transferred to the encryption function deforming section 20a, and the encryption function deforming section 20a deforms the encryption function section and inputs it to the X-stage agitation processing section 3X. In a specific numerical example, now K = 00000000000
00003A (hexadecimal notation), K1 = 00000000
00000016 (upper-level extension, hexadecimal representation), the first stage calculation yields i = 13 and G = 00002
C (hexadecimal notation).

Here, when a transformation for selecting the non-linear processing boxes S1 to Sm is performed, the arrangement of the non-linear processing boxes S1 to Sm by G is S1, S1, S1, S1, S1, S1.
1, S 1, S 6, and S 5, and the modified encryption function unit is input to the first-stage agitation processing unit 31. Hereinafter, the second and subsequent stages are similarly calculated, deformed and input.

As described above, each of the encryption function units 41 to 4n
Is not input in a fixed form, but is transformed based on the information of the common key K and the fixed position intermediate keys K1 to Kn, so that the encryption strength can be increased.

FIG. 8 shows an encryption function modification information calculation unit 20b.
Operates the encryption function transformation unit 20a based on the common key K and the information of the right conversion process statements R0 to Rn-1.

An example of the operation of the transformation unit 20 will be described. First, the corresponding stage information X (representing an arbitrary X-th stage) of the agitation processing unit 3 traced in the encryption function transformation information calculation unit 20b is described. , The common key K, and the exclusive logical logic RRR of the right conversion process statement RX (input to the encryption function unit at the X-th stage), which is obtained by extending all 33 bits or more to 56 bits by setting all bits to 0. Take the sum and call it Z, this Z
Let G be the lower 24 bits of. Further, a value i obtained by adding 1 to a remainder Y obtained by dividing Z by the total number n of stages is calculated. That is, i = 1 + Y = 1 + (K xor RRX) mod n.

Next, the X, i, and G are passed to the encryption function transformation unit 20a, which transforms the encryption function unit and inputs it to the X-stage agitation processing unit 3X. In a specific numerical example, now K = 00000000000
00003A (hexadecimal notation), RR0 = 000000
00001F6 (higher order extension, hexadecimal representation), 1
When the stage is calculated, i = 13, G = 0001CC
(Hexadecimal representation).

Here, when a transformation for rearranging the non-linear processing boxes S1 to Sm is performed, the arrangement of the non-linear processing boxes S1 to Sm is determined by i to be S6, S8, S2, S.
4, S7, S1, S3, S5, and the modified encryption function part is input to the first-stage stirring processing part 31. Hereinafter, the second and subsequent stages are similarly calculated, deformed and input.

As described above, each of the encryption function units 41 to 4n
Is not a fixed form, but has a common key K and a right conversion process statement R
Since the transformation is performed based on the information of 0 to Rn-1, the encryption strength can be increased.

FIG. 9 shows an encryption function transformation information calculation unit 20b.
Is a fixed intermediate key K1 to Kn and a right conversion process statement R0 to Rn-
The encryption function transforming unit 20a is operated based on the information of (1).

An example of the operation of the transformation unit 20 will be described. First, the corresponding stage information X (representing an arbitrary X-th stage) of the agitation processing unit 3 traced in the encryption function transformation information calculation unit 20b is described. , A fixed-position intermediate key KX (representing the X-th fixed-position intermediate key, and 49 bits or more are all 0s);
A right conversion process statement RX (input to the encryption function part at the Xth stage) obtained by expanding 33 bits or more to all 0s and extending it to 56 bits, taking an exclusive OR for each bit with the RRX, and calculating it. Z, and the lower 24 bits of Z are G. In addition, i is calculated by adding 1 to a remainder Y obtained by dividing this Z by the total number n of stages. That is, i = 1 + Y = 1 + (KX xor RRX) mod n.

Next, the X, i, and G are transferred to the encryption function deforming section 20a, and the encryption function deforming section 20a transforms the encryption function section and inputs it to the X-stage agitation processing section 3X. In a concrete numerical example, K1 = 000000
0000016 (high-order extension, hexadecimal notation), RR0 = 0
000000000001F6 (upper-level extension, hexadecimal representation)
Then, when the first stage is calculated, i = 1 and G = 00
01E0 (hexadecimal notation).

Here, when a transformation for selecting the non-linear processing boxes S1 to Sm is performed, the arrangement of the non-linear processing boxes S1 to Sm by G is S1, S1, S1, S1, S1, S1.
1, S8, S5, and S1, and the modified encryption function unit is input to the first-stage agitation processing unit 31. Hereinafter, the second and subsequent stages are similarly calculated, deformed and input.

As described above, each of the encryption function units 41 to 4n
Is not fixed, but is transformed based on the information of the fixed position intermediate keys K1 to Kn and the right conversion process statements R0 to Rn-1, so that the encryption strength can be increased.

FIG. 10 shows an encryption function modification information calculation unit 20.
b is the encryption function transforming unit 20 based on the information of the common key K, the intermediate position keys K1 to Kn and the right conversion process statements R0 to Rn-1.
a is operated.

An example of the operation of the transformation unit 20 will be described. First, the corresponding stage information X (representing an arbitrary X-th stage) of the agitation processing unit 3 traced in the encryption function transformation information operation unit 20b is described. , Common key K, and fixed-position intermediate key KX (representing the X-th fixed-position intermediate key.
) And RRX obtained by extending all 33 bits or more of the right conversion process sentence RX (input to the encryption function unit at the X-th night) to 0 and extending it to 56 bits. , And let it be Z, and let the lower 24 bits of Z be G. In addition, i is calculated by adding 1 to a remainder Y obtained by dividing this Z by the total number n of stages. That is, i = 1 + Y = 1 + (K xor KX xor RRX) mod
n.

Next, the X, i, and G are passed to the encryption function transformation unit 20a, which transforms the encryption function and inputs it to the X-stage agitation processing unit 3X.
In a specific numerical example, K = 00000000000
003A (hexadecimal notation), K1 = 00000000000
0016 (higher order extension, hexadecimal notation), RR0 = 0000
If 00000001F6 (high-order extension, hexadecimal notation), when the first stage is calculated, i = 11 and G = 0001
DA.

Here, when performing a transformation for rearranging the non-linear processing boxes S1 to Sm, the arrangement of the non-linear processing boxes S1 to Sm is represented by S4, S6, S8, S by i.
2, S5, S7, S1, S3, and the modified encryption function section is input to the first-stage mixing section 31. Hereinafter, the second and subsequent stages are similarly calculated, deformed and input.

As described above, each of the encryption function units 41 to 4n
Is not a fixed form, but a common key K, a fixed-position intermediate key K1
ＫKn and the right conversion process statement R0 Rn−1, so that the encryption strength can be increased.

As for the decryption, in all the examples shown in FIGS. 1 and 5 to 10 described above, the order of key input is reversed as in the prior art, so that the key scheduling unit 10a
The generation order of the fixed-position intermediate keys K1 to Kn at K1, K2,
.., Kn, but in the reverse order of Kn,..., K2, K1. That is, Kn is 2 at the first fixed position.
The first fixed position is Kn-1 and the n-th fixed position is K1, and new K1, K2,..., Kn are obtained. Also, only in the embodiment of FIGS. 1 and 5, n-X + 1 is substituted for X in the calculation of i. In all of the above embodiments, the decryption function units of each stage used in decryption are input after being transformed in the same order as in the encryption.

[0065]

As described above, the encryption device according to the present invention is provided with a deforming means for deforming the structure of the encryption processing unit or the decryption processing unit based on predetermined information, so that the encryption strength can be increased. When the deformation means is based on the information of the common key, the encryption strength can be increased. When the deforming means is based on the information of the generated intermediate key, the encryption strength can be increased. When the deforming means is based on the information of the right conversion process statement of the encryption processing unit or the decryption processing unit, the encryption strength can be increased. When the deforming means is based on the information on the common key and the information on the generated intermediate key, the encryption strength can be increased. When the transformation means is based on the information of the common key and the information of the right conversion process statement of the encryption processing unit or the decryption processing unit, the encryption strength can be increased. When the deforming means is based on the information of the generated intermediate key and the information of the right conversion process statement of the encryption processing unit or the decryption processing unit, the encryption strength can be increased. When the deforming means is based on the information on the common key, the information on the generated intermediate key, and the information on the right conversion process statement of the encryption processing unit or the decryption processing unit, the encryption strength can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an encryption device according to an embodiment of the present invention.

FIG. 2 is a selection algorithm of a nonlinear processing box.

FIG. 3 is an algorithm for rearranging non-linear processing boxes.

FIG. 4A shows an algorithm of multi-pass / rotation of a nonlinear processing box, and FIG. 4B shows an algorithm of enlargement / rotation processing.

FIG. 5 is a schematic configuration diagram of an encryption device according to another embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of an encryption device according to another embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an encryption device according to another embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of an encryption device according to another embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of an encryption device according to another embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of an encryption device according to another embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a conventional encryption device.

FIG. 12 is a detailed diagram of an intermediate key generation unit.

FIG. 13 is a detailed diagram of an encryption function unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Plaintext (ciphertext) block 2 Initial transposition part 3 Stirring processing part which corresponds to the encryption processing part and the decryption processing part of this invention 41-4n Encryption function part (It corresponds to the decryption function part at the time of decryption) 4A, 4D Linear transformation unit 4B Exclusive operation sum unit 4C1 to 4Cm (S1 to Sm) Non-linear processing box 51 to 5n Exclusive OR unit 6 Reverse initial transposition unit 7 Cryptographic (plaintext) block 10 Intermediate key generation unit 10a Key scheduling unit 20 Transformation unit 20a Encryption function transformation unit 20b Encryption function transformation information calculation unit R0 to Rn Right conversion process statement L0 to Ln Left conversion process statement K Common key K1 to Kn Positional intermediate key (intermediate key)

Claims (8)

[Claims] 1. A block-like plaintext or ciphertext consisting of a predetermined number of bits is input to a plurality of predetermined stages of encryption processing units or decryption processing units of a plurality of predetermined intermediate keys generated from a common key. In the encryption device of the common key block encryption system, which performs encryption or decryption, provided is a deforming means for modifying the structure of the encryption processing unit or the decryption processing unit based on predetermined information. Encryption device. 2. The encryption device according to claim 1, wherein the transformation unit is based on information on a common key. 3. The encryption device according to claim 1, wherein the transformation unit is based on information on the generated intermediate key. 4. The encryption apparatus according to claim 1, wherein the transformation unit is based on information of a right conversion process sentence of the encryption processing unit or the decryption processing unit. 5. The encryption device according to claim 1, wherein the transformation unit is based on information on the common key and information on the generated intermediate key. 6. The encryption apparatus according to claim 1, wherein the transformation unit is based on information on a common key and information on a right conversion process statement of an encryption processing unit or a decryption processing unit. 7. The encryption apparatus according to claim 1, wherein the transformation unit is based on the information on the generated intermediate key and the information on the right conversion process statement of the encryption processing unit or the decryption processing unit. . 8. The method according to claim 1, wherein the transformation unit is based on information on a common key, information on a generated intermediate key, and information on a right conversion process statement of an encryption processing unit or a decryption processing unit. 2. The encryption device according to 1.