Encryption and decryption technology of ASP. NET Learning Series-symmetric algorithm encryption (I)

I. What is symmetry?Algorithm?

Symmetric algorithms are also called single-key algorithms, that is, encryption keys can be derived from decryption keys. Likewise, decryption keys can also be derived from encryption keys. To put it bluntly, the encryption key and decryption key are the same key. The security of the symmetric algorithm depends on the key. Once the key is known, the message can be encrypted and decrypted.

Ii. encryption and decryption of symmetric algorithms

M indicates plaintext, e Indicates encryption, K indicates key, d Indicates decryption, and C indicates ciphertext.

EK(M) = C// Encrypt the plaintext m using the key K to obtain the ciphertext C

DK(C) = m//Use Key K to decrypt ciphertext C to obtain plaintext m

Iii. Classification of symmetric algorithms

1: Bit-by-bit encryption stream algorithm

2: grouping Algorithm