What are the inverse transformation rules in traditional encryption algorithms?

The commonly used inverse transformation rules in traditional encryption algorithms are permutation inverse transformation, permutation inverse transformation and XOR inverse transformation.

1. Substitution inverse transformation refers to remapping characters in ciphertext to characters in plaintext, which is usually reversed according to the substitution rules used in encryption.

2. Inversion of permutation refers to the inverse operation of character position in cipher text, which can be realized by using permutation table or inverse permutation function.

3. Inverse XOR transformation means that in XOR encryption, encryption and decryption can use the same operation.

The inverse transformation rules are all aimed at symmetric cryptosystems, not public key cryptosystems. Public key cryptosystems usually use different encryption and decryption algorithms, so the implementation of inverse transformation is also different from symmetric cryptosystems.