Data encryption and decryption method based on majority decision

Abstract

The application discloses a data encryption and decryption method based on majority decision, and belongs to the technical field of data encryption and decryption.The application comprises data encryption and data decryption;the data encryption comprises the following steps: an encryption party backs up an original 0 / 1 sequence into N copy sequences; the encryption party randomly flips a plurality of bits in each copy sequence to perform encryption, thereby generating N encrypted sequences; the encryption party distributes the N encrypted sequences to N decryption parties, and each decryption party receives one encrypted sequence; the data decryption comprises the following steps: n effective decryption parties share the received encrypted sequences, wherein n<=N; each effective decryption party performs majority decision on each bit in the encrypted sequence to obtain a decrypted sequence.The application can realize single encryption of the encryption party, joint decryption of a plurality of decryption parties based on majority decision, and normal decryption even when a minority of the decryption parties fail or maliciously forge encrypted sequences by using a statistical method.

Description

Technical Field

[0001] This invention is applicable to data encryption and decryption in multi-user "decentralized" systems, specifically including a data encryption and decryption method based on multiple decision-making, belonging to the field of data encryption and decryption technology. Background Technology

[0002] Encryption and decryption methods are essential in fields such as the internet and communications. Traditional encryption methods involve the encryptor using an encryption key and the decryptor using a matching decryption key. If the decryptor's key is cracked by an eavesdropper, encryption fails. To address this, a decentralized approach is needed, where one party encrypts and multiple parties collaborate to decrypt, effectively "decentralizing" the process. Decryption cannot be performed by a single party; multiple parties must work together. Traditional one-way encryption with multi-party decryption involves splitting the decryption key into several parts, with each party holding one part. Only when all parties reach a consensus can the complete decryption key be reassembled. However, if some decryptors fail or maliciously forge keys, this key-splitting-based encryption / decryption method cannot reassemble a complete and correct decryption key, leading to decryption failure. Summary of the Invention

[0003] In order to "decentralize" the decryption parties and still enable normal decryption even when a few decryption parties fail or maliciously forge the encryption sequence, this invention proposes a method for data encryption and decryption using a multiple-decryption-party selection approach.

[0004] The technical solution of the present invention is as follows:

[0005] A data encryption / decryption method based on multiple decision-making, characterized by including a data encryption method and a data decryption method:

[0006] The data encryption method includes the following steps:

[0007] S1: The encryptor backs up the original 0 / 1 sequence into N copies;

[0008] S2: The encryptor randomly flips several bits in each copy sequence for encryption; specifically, this includes the following steps:

[0009] S21: The cryptographic side determines the flipping ratio p = N for each copy sequence. t / L, where N t L represents the number of bits in the sequence that are flipped, and L is the total number of bits in the sequence.

[0010] S22: The encryptor randomly flips each copy sequence according to the flip ratio p. Flipping means that if the original value of a certain bit is 0, it is flipped to 1, and if the original value of a certain bit is 1, it is flipped to 0.

[0011] S3: The encrypting party distributes N encrypted sequences to N decrypting parties, and each decrypting party receives one encrypted sequence.

[0012] The data decryption method includes the following steps:

[0013] K1: n valid decrypting parties share the received encrypted sequences, where n ≤ N;

[0014] K2: Each valid decrypting party performs a majority decision on each bit in the encrypted sequence to obtain a decrypted sequence, which specifically includes the following steps:

[0015] K21: Each valid decrypting party counts the number of 0s as num0 and the number of 1s as num1 for each bit based on the encrypted sequences received by n valid decrypting parties, where num0 + num1 = n;

[0016] K22: If num0 > num1 for a certain bit, then this bit is determined to be 0; if num0 < num1 for a certain bit, then this bit is determined to be 1; if num0 = num1 for a certain bit, then this bit is randomly determined to be 0 or 1.

[0017] In step S21, the flipping ratio p of each copy sequence can take the same value or different values.

[0018] The value range of the flipping ratio p is (0, 1 / 2), that is, the flipping ratio p is less than 1 / 2.

[0019] In step K1, that n valid decrypting parties share the received encrypted sequences means that each valid decrypting party knows the encrypted sequences received by the remaining n - 1 valid decrypting parties. The fact that n ≤ N indicates that the encryption and decryption method proposed by the present invention can still decrypt normally in the case where a small number of decrypting parties fail or maliciously forge encrypted sequences.

[0020] The advantages of the present invention are as follows:

[0021] 1) It does not use traditional keys for encryption and decryption, directly sends randomly flipped 0 / 1 sequences, and performs multiple independent encryptions through random flipping, reducing the complexity of system design; [[ID=3,2]]

[0022] 2) It "decentralizes" the traditional single decrypting party, uses multiple decrypting parties to cooperate in decryption together, and avoids the inability to complete decryption when a single decrypting party fails. In addition, the "decentralized" method of the present invention can be further applied to the consensus protocol in the blockchain;

[0023] 3) Since each decrypting party is equal, when the number of decrypting parties N is large and the flipping probability p is small, it can still decrypt correctly when a small number of decrypting parties fail or maliciously forge encrypted sequences. Description of the Drawings

[0024] Figure 1 This is a flowchart of the data encryption and decryption process of this invention;

[0025] Figure 2 This is a graph showing the relationship between the probability of decryption errors and the number of valid decryption attempts in a specific embodiment of the present invention;

[0026] Figure 3 This is a graph showing the relationship between the decryption error probability and the flipping ratio in a specific embodiment of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of the invention is not limited in any way.

[0028] This embodiment presents a data encryption / decryption method based on multiple decision-making, such as... Figure 1 As shown, this includes data encryption methods and data decryption methods:

[0029] Data encryption methods include the following steps:

[0030] S1: The encryptor backs up the original 0 / 1 sequence into N copies;

[0031] S2: The encryptor randomly flips several bits in each copy sequence for encryption. The specific steps are as follows:

[0032] S21: The cryptographic side determines the flipping ratio p = N for each copy sequence. t / L, where N t Let p be the number of bits in the sequence that are flipped, and L be the total number of bits in the sequence. The value of p must be in the range of (0, 1 / 2).

[0033] S22: The encryptor randomly flips each copy sequence according to the flip ratio p. Flipping means that if the original value of a bit is 0, it is flipped to 1, and if the original value of a bit is 1, it is flipped to 0.

[0034] S3: The encryptor distributes N encrypted sequences to N decryptors, and each decryptor receives one encrypted sequence.

[0035] The data decryption method includes the following steps:

[0036] K1: n valid decryption parties share the received encrypted sequence, where n ≤ N. That is, each valid decryption party knows the encrypted sequences received by the remaining n-1 valid decryption parties;

[0037] K2: Each valid decryptor performs a multiple-choice decision on each bit of the encrypted sequence to obtain the decrypted sequence. The specific steps are as follows:

[0038] K21: Each valid decryptor counts the number of 0s as num0 and the number of 1s as num1 for each bit based on the encrypted sequences received by n valid decryptors, where num0 + num1 = n;

[0039] K22: If num0 > num1 for a certain bit, then this bit is judged as 0; if num0 < num1 for a certain bit, then this bit is judged as 1; if num0 = num1 for a certain bit, then this bit is randomly judged as 0 or 1.

[0040] For example:

[0041] In this example, it is only one case of random flipping, and the flipping ratio of each copy sequence is the same.

[0042] Data encryption stage:

[0043] The original information sequence is {0110101110}, with length L = 10. Set the flipping ratio p = 0.2, that is, the number of flipped bits N t = pL = 2. Back up N = 5 copy sequences, randomly flip them and send them to 5 decryptors.

[0044] The encrypted sequence received by decryptor 1 is: { 1 1 0 0101110};

[0045] The encrypted sequence received by decryptor 2 is: {0 0 1 1 101110};

[0046] The encrypted sequence received by decryptor 3 is: {011 1 1 1 1110};

[0047] The encrypted sequence received by decryptor 4 is: {0110 0 0 0 110};

[0048] The encrypted sequence received by decryptor 5 is: { 1 11010111 1};

[0049] where the underlines indicate that this bit has been flipped

[0050] Data decryption stage:

[0051] The 5 decryptors share the encrypted sequences they received, and perform a majority decision on each bit. The decrypted sequence obtained is: {0110101110}, which is the same as the original information sequence, and the decryption is successful.

[0052] Specifically, when decryptor 1 and decryptor 2 fail, only the three encrypted sequences received by decryptor 3, decryptor 4, and decryptor 5 remain. At this point, n=3, and the decrypted sequence {0110101110} can still be obtained using the multiple choice decision, resulting in successful decryption. Even when decryptor 1 maliciously forges an encrypted sequence {1000010001}, the multiple choice decision still allows for correct decryption.

[0053] The error probability P of the multiple decision-based data decryption method in this invention e This is related to the number of valid decryption parties, n, and the flipping ratio, p. When each copy sequence has the same flipping ratio, for a certain bit in the sequence, the probability of it being flipped in n flips is p, and the probability of it not being flipped is 1-p. When n is odd, if the number of times this bit is flipped in n flips is greater than or equal to (n+1) / 2, according to the multiple-flipping criterion, this bit will be judged as incorrect. When n is even, the case where num0 = num1 in step K22 needs to be considered separately, in which case there is a 1 / 2 probability of being judged as incorrect. This can be represented as...

[0054]

[0055] in The number of combinations is the number of combinations in which m items are selected from n items at once, regardless of their order.

[0056] In MATLAB simulation software, the error probability P of the encryption / decryption method of this invention when the flipping ratio of each copy sequence is the same was calculated. e The relationship between the number of valid decryption attempts (n) and the flip ratio (p) was analyzed through simulation. When the flip ratio (p) is set to 0.35, the decryption error probability P... e The relationship with the number of backup copy sequences n is as follows: Figure 2 As shown, the decryption error probability P e As the number of effective decryptors, n, increases, the number decreases to 0. The intersection of the curve and the horizontal axis represents the minimum number of effective decryptors required for error-free decryption at this flipping ratio. When the number of decryptors exceeds this minimum, a few decryptors may fail or maliciously forge the encrypted sequence, yet still decrypt correctly. When the number of effective decryptors, n = 21, the decryption error probability P... e The relationship with the flipping ratio p is as follows Figure 3 As shown, the decryption error probability P e Starting from 0, it increases as the flip ratio p increases. Furthermore, Figure 2 and Figure 3 The Monte Carlo simulation results and the formula curves are in good agreement, indicating that the formula derivation is correct.

[0057] It should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art will understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection of the present invention is defined by the scope of the claims. Contents not described in detail in this specification are well-known to those skilled in the art.

Claims

1. A data encryption / decryption method based on multiple decision-making, characterized in that, It includes data encryption and data decryption, specifically including the following steps: 1) The data encryption includes the following steps: 1-1) The encryptor backs up N copy sequences of the original 0 / 1 sequence; 1-2) The encryptor randomly flips several bits in each copy sequence for encryption; S21: The cryptographic side determines the flipping ratio p = N for each copy sequence. t / L, where N t L represents the number of bits in the sequence that are flipped, and L is the total number of bits in the sequence. S22: The encryptor randomly flips each copy sequence according to the flipping ratio p, that is, if the original value of a certain bit is 0, it is flipped to 1, and if the original value of a certain bit is 1, it is flipped to 0; 1-3) The encryptor distributes the N encrypted sequences to N decryptors, and each decryptor receives 1 encrypted sequence; 2) The data decryption includes the following steps: 2-1) n valid decryptors share the received encrypted sequences, where n ≤ N; 2-2) Each valid decryptor performs a majority decision on each bit in the encrypted sequence to obtain a decrypted sequence; K21: Each valid decryptor counts the number of 0s as num0 and the number of 1s as num1 for each bit based on the encrypted sequences received by the n valid decryptors, where num0 + num1 = n; K22: If num0 > num1 for a certain bit, this bit is judged as 0; if num0 < num1 for a certain bit, this bit is judged as 1; if num0 = num1 for a certain bit, this bit is randomly judged as 0 or 1.

2. The data encryption / decryption method based on multiple decision-making as described in claim 1, characterized in that, The value range of the flipping ratio p is (0, 1 / 2).

3. The data encryption / decryption method based on multiple decision-making as described in claim 1, characterized in that, In step S21, the flipping ratio p of each copy sequence takes the same value.

4. The data encryption / decryption method based on multiple decision-making as described in claim 1, characterized in that, In step S21, the flipping ratio p of each copy sequence takes different values.

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