Symmetric ciphering method having infinite cipher key space

Abstract

The invention relates to a symmetric encryption method with an infinite key space, which adopts a group of public computer file sequences as a key; the plaintext of a file to be encrypted takes a fixed-length of m Bits as base unit in a physical layer in which the plaintext is stored; the plaintext is divided into a plurality of plaintext fragments in sequence; when the remaining length is less than m Bits, '0s' are added to cause the length to be m Bits; every file of the key divides a ciphertext into a plurality of key fragments in sequence with the same fixed-length of m Bits as the base unit in a physical layer and gives out an address coding of every key fragment in a form of 'file name / address offset'; if the remaining length of the last key fragment is less than m, '0s' are added to cause the length to be m Bits; the plaintext fragment is presented by any one address of the same key fragment. A code representation is carried out on all plaintext fragments in the plaintext by using the same key fragment so as to obtain the ciphertext.

Description

technical field [0001] The invention belongs to the technical field of information security, and relates to a method for encrypting and decrypting using symmetric key technology. Background technique [0002] Current cryptographic techniques can be divided into two categories: symmetric encryption and asymmetric encryption. Symmetric encryption uses the same key during encryption and decryption; asymmetric encryption divides the key into a public key and a private key. The public key is used for encryption and the private key is used for decryption. This characteristic of asymmetric encryption solves a key problem that has plagued the use of ciphers for a long time-the key distribution problem. At present, when transmitting confidential information on the network, an asymmetric encryption method is generally used to transmit the key used in this communication, and then a symmetric encryption method is used for confidential communication. This is because under the same comp...

AI Technical Summary

Problems solved by technology

[0009] (2) Known plaintext attack

[0011] From the mechanism analysis of known plaintext attacks, we can know that if the correspondence between plaintext and ciphertext is not a one-to-one mapping, but a one-to-many algebraic relationship, then the difficulty of known plaintext analysis attacks will be greatly increased.

Images