JPH11338347A - Cipher key formation and encryption method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make illicit decipherment difficult and to make the high-speed processing with an electronic computer possible by forming two pseudo-random number sequences, changing the sequence of the one pseudo-random number sequence in accordance with the value of another pseudo-random number sequence and outputting the pseudo- random number sequence after a sequence change as a cipher key. SOLUTION: The pseudo-random number RF is set at RX=RX0 for the purpose of initialization. The pseudo-random number RX is stored in an array element V[0] and a subscript I for storing the pseudo-random number RX formed in the subsequent processing into the array V is initialized to I=1 (S402, S403). The next pseudo-random number RX is calculated and is stored in the array element V[I] of the subscript I and further the subscript I of the array V for assigning the array element for storing the pseudo-random number RX to be calculated next is added (S404 to S406). A pointer P is positioned at the word at the top of plaintext/ciphertext data and the first/second pseudo-random number are calculated (S409). Next, the processing to obtain the agitation random numbers agitating the first pseudo-random number sequence is executed and Bellman processing is executed with the fetched pseudo-random number Rn as a key.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encryption key generation method used for encrypting data during data communication and data storage, and to encrypt data using the encryption key generated by the encryption key generation method. The present invention relates to an encryption method to be encrypted.

[0002]

2. Description of the Related Art Conventionally, various encryption methods have been devised for performing communication in secret.

[0003] Among them, Caesar ciphe (Caesar ciphe)
There is something called r). In the Caesar cipher, when a plaintext cipher consisting of English characters is considered, the plaintext is encrypted by performing an operation of shifting the plaintext by n characters. For example, given a plain text consisting of the following alphabets:
A is encrypted by shifting A by one character such as B and C by D. Plaintext HELLOW Ciphertext IFMMPX In this case, a valid reader is notified in advance that n = 1. This makes it difficult for an unauthorized eavesdropper to decipher. In the Caesar cipher, n is a key of the cipher. In this Caesar cipher, there are the following plaintext and ciphertext, and when n = 3, the following conversion table is used. Plaintext HELLOW Ciphertext KHOORZ [Conversion Table] Plaintext ABCDEFGHIJKLMNOPQRS
TUVWXYZ Ciphertext DEFGHIJKLMNOPQRSTUV
WXYZABC There is also what is called polytable encryption. In the Caesar cipher, if the value of n, which is an encryption key, is fixed, unauthorized decryption can be easily performed based on the appearance frequency of characters in cipher text. As a remedy, a set of the number of characters to be shifted
There is a method in which 2｝ is applied in order. Plaintext HELLOW key 132132 Ciphertext IHNMRY In this cryptography, the following conversion table is used. Plaintext ABCDEFGHIJKLMNOPQRSTU
VWXYZ Code 1 BCDEFGHIJKLMNOPQRSTUV
WXYZA Encryption 2 CDEFGHIJKLMNOPQRSTUVW
XYZAB Encryption 3 DEFGHIJKLMNOPQRSTUVWX
If there is one conversion table for Caesar cryptography with a fixed YZABC key,
Since three conversion tables are used, it is called polytable encryption.

[0004] Next, Vernam cipher
There is a cryptography called. This was Gilber in 1917
t Suggested by Vernam. Prepare a random number of the same length as the number of characters in the plain text, perform polytable encryption using the random number of as a key, and dispose of the random number. According to this Vernam cryptography, a ciphertext with the following relationship is obtained. Can be Plaintext HELLOW Random number 314159 Ciphertext KFPMTF It is said that this Burnham cryptography has no fear of illegal decryption in principle.

Next, Verman cipher
There is something called. This Bellman cryptography effectively utilizes an exclusive OR operation of a computer. That is, in an electronic computer, an encryption method using an exclusive OR (xor) of logical operations is frequently used. This is because the program is simple, and encryption and decryption can be performed at an extremely high speed by a computer. In the case of a normal computer, the exclusive OR operation requires only a short time of 1/5 or less of the multiplication. Normal computer registers are 32 bits,
Can store 4 characters. A 32-bit secret bit pattern K is prepared and used as an encryption key. It is assumed that four characters of plaintext are X and four characters of encryption are Y. With Y = XxorK and X = YxorK, encryption and decryption can be performed.

This is because the following relationship holds when focusing on one bit. XK XxorK (XxorK) xorK 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 The processing time of this Bellman cryptosystem on an electronic computer is about 5 units / 32 bits. Here, one unit is the processing time of the basic instruction of the computer, which is also called a machine cycle.

On the other hand, there has been proposed a method of generating a pseudo-random number using an electronic computer. A typical one is a joint law.

If a random number is represented by {Rn}, its recurrence formula is as follows. Rn + 1 = ((Rn * A) + C) mod M In M, (2 (the number of bits of the register of the computer))
Power) is often used. A and C are constants. When M is the “number of powers of 2” as described above, it is appropriate to assign A to the remainder of 5 by dividing by 8 and C to an odd number.

Here, since M is often known,
{Rn} is considered to be generated from {R ₀ , A, C}. This {R ₀ , A, C} is referred to as a seed of a pseudo-random number. In the case of an electronic computer, three numbers {R ₀ , A, C} may be used to generate a pseudo-random number by a congruential method. In an electronic computer, it is easy to select an appropriate number for each encryption using date and time. Therefore, it is conceivable to generate a pseudo Vernam cipher using pseudorandom numbers based on a joint method.

However, if the first few characters of the plaintext are known, this cipher can be easily deciphered. X in plain text
Assuming that n and the encryption character are Yn, Y ₀ = X ₀ + R ₀ Y ₁ = X ₁ + (R ₀ * A + C) Y ₂ = X ₂ + ((R ₀ * A + C) * A + C) This is because a ternary equation relating to R ₀ , A, C} can be estimated.

A pseudorandom number generated by a simple formula or a recurrence formula can be illegally decoded by the above method.

Simply increasing the number of terms and operators in an equation or recurrence equation is not safe for unauthorized decryption using an electronic computer. Historically, examples of breaking Enigma ciphers are famous. The Enigma cipher uses a pseudo-random number {Rn = ((C ₀ n-th mod M ₀ ) * (C ₁ n-th mod M ₁ ) *... (Cx n-th mod Mx)) mod M} It was a cryptographic method.

[0013]

As described above, polytable encryption using a simple pseudo-random number has a problem in security, and has been considered to be inappropriate as a public encryption method.

However, DES (Data encryption Stan)
Cryptographic methods such as dard) have the problem that the processing time is long because of including bit manipulation, and are not suitable for encrypting large amounts of data. In addition, public key cryptography such as RSA, which is expected to be ciphers between a large number of communicating parties in the future, is 10
It is said that the processing time is about 0 times longer.

By the way, D, which is a typical example of the public system encryption, is used.
The processing time of a normal computer of ES is SSLea
In the case of Eric Young's program, it is about 200 units / 32 bits. In addition, the processing time of a typical computer using RSA, which is a typical example of public key cryptography, is 2 seconds.
It is about 000 units / 32 bits.

An encryption method using pseudo-random numbers can be processed at high speed by an electronic computer.
It can contribute to the encryption of large amounts of data and the practical use of public key cryptography.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides an encryption key generation method and an encryption method using pseudo-random numbers that can be processed at high speed by an electronic computer and that make it difficult to perform unauthorized decryption. To provide.

[0018]

In order to achieve the above object, the present invention generates two pseudo-random number sequences and changes the order of one pseudo-random number sequence based on the value of the other pseudo-random number sequence. ,
The pseudo-random number sequence after the order change is output as an encryption key. Further, one of the two pseudo-random number sequences is generated using all or a part of the other pseudo-random number sequence. Further, the present invention is characterized in that data to be encrypted is encrypted using an encryption key generated by the above-described encryption key generation method.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of a system for generating an encryption key using the encryption key generation method of the present invention, and encrypting and outputting plaintext using the encryption key. , A processing device 101 for performing a process of generating a pseudo-random number sequence and a process of generating an encryption key, and a memory 102 for storing a program for the process executed by the processing device 101 and the generated pseudo-random number sequence and the like. Processing device 1
01 stores an encryption / decryption program 103 for performing an encryption process and a decryption process based on the encryption key generated by the device 01, and includes a working memory 104 for storing the generated pseudo-random number sequence and the like. . The processing device 101 can be configured by an electronic computer or a dedicated arithmetic device.
In addition, the encryption / decryption program 103 is
01 as an external function.

First, the principle of the present invention will be briefly described. The present invention provides two pseudo-random number sequences {RXn}, {R
Yn}, the order of the first pseudo-random number sequence {RXn} is changed based on the value of the second pseudo-random number sequence {RYn}, and the pseudo-random number sequence {Rn} after the order change is generated. The pseudo-random number sequence {Rn} generated in this way is a mixture of {RXn}. Using the pseudo random number sequence {Rn} as an encryption key, an encryption process and a decryption process are performed.

According to this method, it is difficult to create an equation for estimating the "seed" of the pseudo-random sequence from a part of {Rn}. Even if there is a method for estimating the generation equation of {Rn}, at least the {RX
It is anticipated that more than {n} {Rn} will be needed. here,
As for {RYn} used for stirring of {RXn}, part or all of {RXn} may be used, and this does not impair safety. {RYn} to {RX
When part or all of n} is used, {R
The generation time of n｝ can be further reduced.

FIGS. 2 and 3 show a process of generating a pseudo-random number sequence {Rn} by applying specific numerical values to the present invention. Hereinafter, the principle of the present invention will be specifically described with reference to FIGS.

<Premises> • Number of bits of register length: 4 • RX (n + 1) = (RXn * A + C) modM RYn = RX (n + Q) • Number of elements in array V [I], V [0] to V [Q] -1]
RX ₀ = 3, A = 5, C = 7, M = 2 to the fourth power = 16,
Q = 4 <Result> In = RYnmmodQ, and the value of Rn is an array element V
After setting the value stored in [In], the array element V [I
n] The value of RYn is stored in <Process> (a) Calculation and storage of RX _{0 to} RX ₃ RX (n + 1) = (RXn * A + C) mod M = (RX
from n * 5 + 7) mod16 calculates _{RX 1, RX 2, RX 3} , RX 0, RX 1, R
Store each of X ₂ and RX ₃ in array elements V [0] to V [3] V [0] = RX ₀ = 03, V [1] = RX ₁ = 06, V
[2] = RX ₂ = 05, V [3] = RX ₃ = 00 (FIG. 2
(B) Calculation of RYn From RYn = RX (n + 4), RY ₀ , RY ₁ , RY ₂ , R
Calculate Y ₃ , RY ₄ ,... RY ₀ = 07, RY ₁ = 10, RY ₂ = 09, RY ₃
= 04, RY ₄ = 11, RY ₅ = 14, RY ₆ = 1
3, RY ₇ = 08, RY ₈ = 15, RY ₉ = 02,
RY ₁₀ = 01, RY ₁₁ = 12, (see FIG. 2 ()) (c) Calculation of In, determination of V [In], determination of Rn, storage of new pseudorandom number in V [In] <n = 0 _{> · I 0: I 0 =} RY 0 modQ = (07) mod4 = 03 ( FIG. 2 () _{reference) · V [I 0]:} V [3] · R 0: R 0 = V [3] = 00 ( (See FIG. 2) V. [I ₀ ] New stored value: V [3] = RY ₀ = 07 (see FIG. 2 ()) <n = 1> I ₁ : I ₁ = RY ₁ modQ = (10 ) mod4 = 02 reference (FIG. 2 ()) · V [I 1]: V [2] · R 1: reference _{R 1 = V [2] =} 05 ( FIG. 2 ()) · V [I 1] new stores value: (see Fig. 2 ()) V [2] = RY 1 = 10 <n = 2> · I 2: I 2 = RY 2 modQ = (09) mod4 = 01 ( FIG. 2 () refer) · V [ _{I 2]: V [1]} · R 2: R 2 = V [ ] = 06 (FIG. 2 () refer) · V [I _2] New storage _{value: V [1] = RY 2} = 09 ( FIG. 2 () refer) <n = 3> · I 3: I 3 = RY 3 modQ = (04) (see Figure 2 ()) mod4 = 00 · V [I 3]: V [0] · R 3: ( see Fig. _{2 ()) R 3 = V} [0] = 03 · V [I _2] new storage _{value: V [0] = RY 3} = 04 ( see FIG. _{2 ()) <n = 4} > · I 4: see _{I 4 = RY 4 modQ = (} 11) mod4 = 03 ( FIG. 2 () V [I ₄ ]: V [3] R ₄ : R ₄ = V [3] = 07 (see FIG. 2 ()) V [I ₄ ] New stored value: V [3] = RY ₄ = 11 (see FIG. 2 ()) The same applies to <n = 5> and thereafter.

As described above, the following pseudo-random number sequence ｛R
n} is obtained.

{Rn} = {R ₀ = 00, R ₁ = 05, R ₂
= 06, R ₃ = 03, R ₄ = 07, R ₅ = 10, R ₆ = 0
9, a｝ (see FIG. 2 ()). The above pseudo-random number sequence {Rn} = {00, 05, 06, 0
When, for example, Caesar encryption processing is performed using 3, 07, 10, 09, a｝ as an encryption key, the following encrypted text is obtained from the plain text. Plaintext CIPHER encryption key 0 5 6 3 7 10 Encrypted text CNV KLB FIG. 4 is a flowchart showing the procedure of the encryption key generation process and the encryption process of the present invention. In the encryption key generation processing shown in this flowchart, a first pseudo-random number sequence {RXn} is calculated by the following equation (1). RX (n + 1) = (RXn * A + C) modM (1) Also, {RY used for stirring this pseudo-random number sequence {RXn}
n｝ is calculated by the following equation (2). RYn = RX (n + Q) (2) In the flowchart of FIG. 4, all elements of the pseudo-random number sequence {Rn} required for encryption / decryption are generated and then encrypted / decrypted at once. In this case, each time one pseudo-random number Rn is calculated, encryption /
Decryption is performed. The word here means a word expressing one unit when expressing the length of data inside the computer.

FIGS. 5 to 10 show the above equations (1) and (2).
, Where RX ₀ = 3, A = 5, C = 7, M = 2 to the eighth power = 256, Q = 16, and array elements V [0] to V [Q when the pseudo-random number sequence {Rn} is calculated -1] = V [1
5] and a specific example of the pseudo-random number sequence {Rn}. FIG. 11 and FIG. 12 show a pseudo-random data R as a plaintext data (four characters of one word) and a mixed encryption key.
This shows a process of encrypting plaintext data (4 characters of one word) by taking an exclusive OR with n. Hereinafter, FIG.
The encryption key generation processing and the encryption processing of the present invention will be described with reference to FIGS. In the description of the flowchart of FIG. 4, for the sake of convenience with reference to specific examples shown in FIGS. 5 to 12, the constants and the like used in the flowchart of FIG. RX ₀ = 3, A = 5, C = 7, M = 2 to the eighth power = 256,
Q = 16 First, in order to calculate the pseudo-random number sequence {RXn} by the above equation (1), RX =
RX0 is set (step 401). Next, the pseudo random number RX initialized in step 401 is stored in the array element V [0] (step 402). Then, the subscript I for sequentially storing the pseudo random numbers RX generated in the subsequent processing in the array V is initialized to I = 1 (step 403).

Next, the next pseudo random number RX is calculated by the above equation (1) (step 404). The pseudo random number RX calculated in step 404 is assigned to the array element V of the subscript I.
It is stored in [I] (step 405), and the suffix I of the array V that specifies the array element for storing the pseudorandom number RX calculated next is incremented by one (step 406).

The processing from step 404 to step 406 is repeated until the subscript I reaches a predetermined value, here, I = Q = 16. By this processing, 16 pseudo random numbers R
X _{0 to} RX ₁₅ are generated and stored in this order in array elements V [0] to V [15].

The results are the respective values shown in FIGS.

Thereafter, the pointer P is positioned at the first word of the plaintext / ciphertext data (step 408, FIG. 11 ()).
), A first pseudo-random number RX (n + Q) and a second pseudo-random number RYn are calculated by the above equation (2) (step 4).
09).

Next, in order to obtain a stirring random number Rn obtained by stirring the first pseudo random number sequence {RXn}, steps 410 to 412 are executed. First, V [0] to V [Q−
1] = V [15] In order to obtain any of the pseudo random numbers RX, the subscript In of the array V is determined by the following equation (3) (step 410). In = RX / (2M / Q) (3) Each value of RYn = RX (n + 16) is shown in FIG. 5 (), and the value of In corresponding to these values is shown in () of FIG.

Next, the subscript In determined at step 410
To select an array element V [In], and
The pseudo random number stored in [In] is set as the random number Rn (step 411, see FIG. 5 ()). Further, RYn generated in step 409 is stored in array element V [In] (step 412). Thereby, the array element V [I extracted in step 411 as the stirring random number Rn
n] is changed to a new pseudo random number RYn. For example, if RYn is RY ₀ = 211 then I _0, which is the calculation result of the equation (3), becomes I ₀ = 003, and the array V [3] is selected. Therefore, in this case, the value V [3] = 080 stored in the array V [3] is the value of the random number R ₀ . Then, the value of RY ₀ = 211 is stored again in the array V [3]. Further, when the RYn is a _{RY 1 = 038, (3)} it 1 is the result of the operation expression is I ₁ = 006, and the sequence V [6] is selected. Therefore, in this case, the value V [6] = 233 stored in the array V [6]
There is a value of agitating the random number R _1. Then, the value of RY ₁ = 038 is stored again in the array V [6].

Next, Bellman encryption processing is performed using the pseudo random number Rn extracted in step 411 as a key. Specifically, the plaintext word pointed by the pointer P and the step 41
An exclusive OR with the pseudorandom number Rn determined in step 1 is obtained, and encryption / decryption is performed (step 413).

For example, the first execution of step 413,
That is, when the encryption key Rn is R ₀ = 080, the first four letters A, B, C, and D of the plaintext data are changed as shown in FIG.
(B) Encrypted contents shown in (). Step 4
13, the encryption key Rn is R ₁ = 23
In the case of 3, E, which is the next four English characters of the plaintext data,
F, G, and H are encrypted to the contents shown in parentheses in FIG.

The execution of step 413 means that the encryption / decryption of one character and four characters has been completed.
Is positioned to the next word (step 414). Next, it is determined whether or not the end of the plaintext data / ciphertext data to be processed is reached (step 415). If the encryption / decryption has been completed up to the last word of the plaintext data / ciphertext data, When the processing is completed and the encryption / decryption is not completed up to the last word, the process returns to step 409, and the same operation is repeated to encrypt the plaintext data or decrypt the ciphertext data. Steps 409 to 415
, The first pseudo-random number sequence {RXn} stirred by the second pseudo-random number sequence {RYn},
That is, the operation target data is encrypted / decrypted by the agitation encryption key pseudo random number sequence {Rn}.

According to the present invention, when the number of elements of the array V is 256, 256 32-bit data are required. This means that a continuous text of 1024 characters is known. Therefore, even if the method of generating the agitation encryption key pseudo-random number sequence {Rn} can be estimated, it is difficult to imagine that it is possible to estimate up to 1024 consecutive plaintexts. Furthermore, the key point of the above-mentioned Vernam cipher is that “random numbers are disposable”. This can be performed by changing the number (seed of the pseudorandom number) from which the pseudorandom number is generated every time encryption is performed.

In order to make the pseudo-random number disposable, it is sufficient to generate {RX ₀ , A, C} every time encryption is performed. Therefore, if Nt is a value obtained from date and time and Nd is a value obtained from plaintext data, Nt and Nd are values that change every time encryption is performed. The following calculation is performed using it. RX ₀ = Nt + Nd A = (RX ₀ * 8 + 5) mod (2 to the 23rd power) C = (RX ₀ * 2 + 1) mod (2 to the 15th power) The seeds of the pseudo-random numbers are Nt and Nd. It can fit in 64 bits. Therefore, the seed of the pseudorandom number is encrypted by a secure encryption process such as DES or RSA and transmitted to a necessary portion (for example, a communication partner). Then, using the seed of the pseudorandom number, the pseudorandom number sequence ｛R
n} is generated at the transmission source and the transmission destination, and encryption processing is performed on the transmission side by the generated pseudo-random number sequence {Rn}, and decryption processing is performed on the reception side, thereby enabling highly secure communication. . If the seed of this pseudo-random number is encrypted using a public encryption scheme such as DES, the entire present invention becomes a public encryption scheme. If the seed of this pseudo-random number is encrypted using public key encryption such as RSA, Thus, the whole invention becomes public key cryptography.

By the way, dividing by a power of 2 or finding a remainder is implemented as a basic instruction in an ordinary computer. Therefore, the processing time in a normal computer of this embodiment is about 20 units / 32 bits as follows. Pseudorandom number calculation Multiplication (10 units) and addition (1 unit) Subscript determination Shift (1 unit) Stirring random number output Transfer (1 unit) Encryption / decryption Exclusive OR (1 unit) and addition (1 unit) Pseudorandom number recording Transfer (1 unit) Loop processing Addition (1 unit) and decision branch (1 unit) Total 18 units For example, in encryption processing of a computer, 131,072 bits (16,384 characters) are used as the unit of encryption. There are many examples. The processing time in the DES for encryption / decryption of the 16,384 character data and the processing time in the present invention is as follows.
The processing time of the present invention is about one tenth of DES. [DES processing time] 200 units * (16,384 characters / 4 characters) = 819,
200 units [Processing time of the present invention] Preparation (200 units * 2) + (20 units * 256) +100 units = 5,620 units However, in the above (20 units * 256) 256, the constant Q is Q = 256. The value of the case. Encryption / decryption 20 units * (16,384 characters / 4 characters) = 81,92
0 units Total + = 5,620 units + 81,920 units =
87,540 units Since the security in the case of using the present invention depends only on the security of the encryption applied to the “seed of pseudo-random numbers”, by using the present invention, the symmetric encryption method represented by DES or the RSA The encryption / decryption processing can be significantly speeded up without impairing the security of the representative public key cryptography.

[0040]

As described above, according to the present invention,
It is possible to generate an encryption key using pseudo-random numbers that can be processed at high speed by an electronic computer and makes unauthorized decryption difficult. In addition, by encrypting the data to be encrypted using the encryption key, it is possible to transmit and receive data at high speed and with high security. In particular, now that communication media such as the Internet have been widely used at the general public level, communications requiring high security such as e-commerce using general-purpose computers such as personal computers have been realized. In such an environment, by applying the present invention, it is possible to greatly contribute to high-speed and highly secure data transmission and reception, and to reduce communication traffic.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a system for generating an encryption key according to the present invention.

FIG. 2 is a diagram illustrating an example of a pseudo-random number sequence generated using the present invention.

FIG. 3 is a view showing a continuation of FIG. 2;

FIG. 4 is a flowchart showing a processing procedure of an encryption key generation method and an encryption method of the present invention.

FIG. 5 illustrates a change in stored values of array elements V [0] to V [Q-1] = V [15] when a pseudo random number sequence {Rn} is calculated and a specific example of a pseudo random number sequence {Rn}. FIG.

FIG. 6 is a view showing a continuation of FIG. 5;

FIG. 7 is a view showing a continuation of FIG. 5;

FIG. 8 is a view showing a continuation of FIG. 5;

FIG. 9 is a view showing a continuation of FIG. 5;

FIG. 10 is a view showing a continuation of FIG. 5;

FIG. 11 shows a process of encrypting the plaintext data (four characters of one word) by taking an exclusive OR of the plaintext data (four characters of one word) and the pseudo-random number Rn which is a mixed encryption key. FIG.

FIG. 12 is a diagram illustrating an exclusive OR result of plaintext data (four characters of one word) and a pseudo random number Rn that is a mixed encryption key.

[Explanation of symbols]

101: processing device, 102: memory, 103: encryption /
Decryption program.

Claims (3)

[Claims] 1. A method for generating an encryption key using a computer or a dedicated arithmetic device, comprising: generating two pseudo-random number sequences; and ordering one of the pseudo-random number sequences based on the value of the other pseudo-random number sequence. And outputting the pseudo-random number sequence after the order change as an encryption key. 2. The encryption key generating method according to claim 1, wherein one of the two pseudo-random number sequences is generated using all or a part of the other pseudo-random number sequence. 3. An encryption method, wherein data to be encrypted is encrypted using an encryption key generated by the encryption key generation method according to claim 1.