Russian copulation

In cryptography, Russian copulation is a method of rearranging plaintext before encryption so as to conceal stereotyped headers, salutations, introductions, endings, signatures, etc. This obscures clues for a cryptanalyst, and can be used to increase cryptanalytic difficulty in naive cryptographic schemes (however, most modern schemes contain more rigorous defences; see Ciphertext indistinguishability). This is of course desirable for those sending messages and wishing them to remain confidential. Padding is another technique for obscuring such clues.