noun
substitution cipher
A cryptographic method where each character in the plaintext is replaced by another according to a fixed system.
換字式暗号は、文字を別の文字に置き換える暗号方式です。
A substitution cipher is an encryption method that replaces characters with other characters.
Transposition cipher, which rearranges the order of characters rather than substituting them.
Compound of 換字 (substitution of characters) + 式 (style, method) + 暗号 (cipher, code).