CN115664635A

CN115664635A - Method for super-long key

Info

Publication number: CN115664635A
Application number: CN202211276183.0A
Authority: CN
Inventors: 李朝铭
Original assignee: Shandong New Generation Information Industry Technology Research Institute Co Ltd
Current assignee: Shandong New Generation Information Industry Technology Research Institute Co Ltd
Priority date: 2022-10-19
Filing date: 2022-10-19
Publication date: 2023-01-31

Abstract

The invention provides a method for an ultra-long secret key, belonging to the technical field of information security. The block cipher encryption can use an ultra-long key under the condition of basically unchanged performance, and the difficulty of breaking the block encryption by an exhaustion method is increased. The method comprises the following steps of using an ultra-long key with unlimited length, dividing the ultra-long key into M groups according to the length N of an original group encryption key, wherein M is more than or equal to 1, and the length of each group of keys is equal to N; when the block encryption is carried out, plaintext of different blocks is encrypted by using any one of M groups of keys; in the encryption process, a polling mode is adopted to obtain the key, and when the cipher texts of different groups are decrypted, one group in the M groups of keys is selected for decryption.

Description

Method for super-long key

Technical Field

The invention relates to an encryption method of an ultra-long secret key, belonging to the technical field of information security.

Background

For information security, data needing to be kept secret needs to be encrypted, and the used ciphers are divided into a block cipher and a stream cipher according to different encryption technologies. The block cipher is characterized in that a digital sequence represented by a plaintext message in an encoding mode is divided into groups with equal length, n is temporarily defined as n, n >0, each group is converted into an array digital sequence with equal length under the control of a key, the block cipher solves the problem that the length of the key is consistent with that of a plaintext, blocks with fixed length are encrypted by the block cipher, the length of the plaintext to be encrypted possibly exceeds the block length of the block cipher, iteration is needed to be carried out on the block cipher at the moment so as to encrypt the long plaintext, and the iteration method is a mode of the block cipher. The stream cipher is that the plaintext and the key have the same length, and the exclusive or operation is performed one by one to obtain the ciphertext, for example, 100m of plaintext has 100m of key.

The advantages of using a block cipher are: the plaintext information has good expansibility and sensitivity to insertion, does not need key synchronization, and has strong applicability; the disadvantages are that: the encryption speed is slow, the error is diffused and propagated, and the exhaustion method is easy to decipher. In order to reduce the probability of exhaustion of the key, the length of the key generally needs to be increased, but the length of the key is affected by the length of the packet, generally the length of the key does not exceed the length of the packet, and some encryption algorithms can use the key with the length of multiple (generally not more than several) packets through a plurality of rounds of iteration, but the encryption and decryption speed is slower, so the length of the key is still limited in a certain length range.

Disclosure of Invention

The invention aims to provide an encryption method of an ultra-long key, which can enable the block cipher encryption to use the ultra-long key under the condition of basically unchanging performance and increase the difficulty of breaking the block cipher by an exhaustion method.

In order to achieve the purpose, the invention is realized by the following technical scheme:

1) Using an ultra-long key with unlimited length, dividing the ultra-long key into M groups according to the length N of the original grouping encryption key, wherein M is more than or equal to 1, and the length of each group of secret keys is equal to N;

2) When the block encryption is carried out, plaintext of different blocks is encrypted by using any one of M groups of keys; in the encryption process, a polling mode is adopted to obtain a key, and the specific mode is as follows:

the first M groups of plaintext are sequentially encrypted according to the sequence corresponding to the M groups of keys, and the (M + 1) th group of plaintext starts to be sequentially encrypted from the first group of keys and circulates until the plaintext encryption is completed;

3) When the grouping decryption is carried out, the ciphertext of different groups is decrypted by using one group in the M groups of keys;

preferably, the same group of plaintext may be encrypted by repeatedly selecting a key used by another group of plaintext, and the same group of ciphertext may be decrypted by repeatedly selecting a key used by another group of ciphertext.

Preferably, when the different block plaintext encryption selection key set and the different block ciphertext decryption selection key set are used, a hash algorithm can be further adopted to obtain the key from the key set.

Preferably, the very long key segments are stored in different storage devices.

The invention has the advantages that: the invention can use the super-long key under the condition that the performance of the encryption and decryption of the block cipher is basically unchanged, thereby greatly increasing the difficulty of decoding the block cipher by an exhaustion method and improving the safety of information.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.

FIG. 1 is a schematic view of the flow structure of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

As shown in the figure, the method for the ultra-long key is mainly used in a symmetric block encryption algorithm, the key with unlimited length can be used, the ultra-long key is divided into a plurality of groups according to the length of the original block encryption key, the plaintext of different blocks selects one group of the ultra-long key blocks for encryption, the keys used by the plaintext of different blocks may be different, the decryption is similar, and the ciphertext of different blocks is decrypted by using different keys.

If the block encryption algorithm uses N byte keys, the super-long key may be M times (M > = 1) N, and the super-long key is divided into M groups when encrypting, and the length of each group of keys is equal to N. In the AES standard specification, the packet length is only 128 bits, that is, each packet is 16 bytes, the key length may be 128 bits, 192 bits, or 256 bits, that is, 16, 24, or 32 bytes, if AES is encrypted with the longest 256 bits (N =32 bytes), the super-long key is an integer multiple of 32 bytes, for example, 32000 bytes (M = 1000), the super-long key is divided into 1000 groups by 32 bytes, and if AES encryption using the super-long key is used, 1 group is selected from 1000 groups each time.

When the block encryption is carried out, plaintext of different blocks is selected to be encrypted by using one of M groups of keys, and the keys used for different block encryptions may be the same or different.

When the groups are decrypted, the ciphertext of different groups is selectively decrypted by using one group in the M groups of keys, and the keys used for decrypting different groups may be the same or different.

Different groups of encryption and decryption select a key group, and a key can be acquired from the key group by polling or by adopting a Hash or other algorithm. When polling is adopted, if M =1000, the first group adopts the first group key in 1000 groups, the second group adopts the second group key in 1000 groups, the third group adopts the third group key in 1000 groups, and so on, the first thousand groups adopt the first thousand group key in 1000 groups, and the first thousand group adopts the first group key in 1000 groups, and the process is repeated for 8230, 8230and 1000 groups.

The method using the ultra-long key can be applied to different block encryption algorithms, the encryption strength is not reduced, more resources are not needed during encryption and decryption, the performance depends on the original block encryption algorithm, but the method greatly increases the difficulty of exhaustive decryption, if the ultra-long key is long enough, the time of exhaustion is infinitely long, and the exhaustive decryption is almost impossible.

The super-long key in the method can be stored in a segmented mode, for example, the super-long key can be stored in different segments (each segment is very long) and stored in different U disks, different persons are handed to and stored in different safe boxes, and the persons related to the key can be decrypted only in the presence of the key, so that the safety is further improved.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An encryption method of a super-long key is characterized by comprising the following steps:

3) When the groups are decrypted, the ciphertext of different groups is selected to be decrypted by using one group in the M groups of keys.

2. The method according to claim 1, wherein the same set of plaintext is encrypted by repeatedly using the keys used by other sets of plaintext, and the same set of ciphertext is decrypted by repeatedly using the keys used by other sets of ciphertext.

3. The encryption method of ultra-long key as claimed in claim 1, wherein when the different block plaintext encryption selection key set and the different block ciphertext decryption selection key set are used, a hash algorithm is further used to obtain the key from the key set.

4. The encryption method of claim 1, wherein the super long key segments are stored in different storage devices.