The principle of hill cipher
Hill password is a multi-letter substitution password, and its encryption process can be simply summarized as the following steps:
1. Select a key matrix k, which contains a positive integer n and n different letters.
2. Divide plaintext into blocks of length n, and each block corresponds to a column vector.
3. For each column vector, multiply by the key matrix k to get a new column vector.
4. Convert each new column vector into a letter to obtain ciphertext.
The decryption process is similar to the encryption process, and only the inverse matrix of the key matrix needs to be multiplied.
Advantages and disadvantages of hill cipher
Hill password has the following advantages:
1. The encryption speed is fast, which is suitable for the encryption of large-scale data.
2. The key space is large and it is difficult to crack.
3. The encryption strength is high, and it can resist general password cracking attacks.
However, the Hill password also has some disadvantages:
1. The plaintext must be divided into blocks of length n. If the plaintext length is not a multiple of n, it needs to be padded.
2. The key matrix must be reversible, otherwise there will be errors in the decryption process.
3. The choice of key matrix may affect the encryption strength, so it needs to be carefully selected.
Application of Hill Cryptography
Hill cipher is widely used in military and commercial fields, especially during World War II, which was used by allied forces to encrypt communications. In addition, Hill password is also used in the field of computer network security, such as password protection of websites and encryption of data transmission.