as the methods shown above, a null cipher could be plaintext words with nulls placed in designated areas or even a plaintext message broken up in different positions with a null at the end of each word. However, a message with only a couple nulls (for example, one at the beginning and one at the end) is not a null cipher. Usage In general, it is difficult and time-consuming to produce covert texts that seem natural and would not raise suspicion, but if you are unable to use an advanced encryption method and have plenty of time, it might be a good option. If no key or actual encryption is involved, the security of the message relies entirely on the secrecy of the concealment method. Null ciphers in modern times are used by prison inmates in an attempt to have their messages pass inspection. Null ciphers are one of three major cipher types in classical cryptography, but it is less well known as the others. It is often marked as a subcategory of transposition ciphers, but that is not true, as transposition ciphers are scrambled messages. See also Transposition cipher Substitution ciphers Acrostic Nulls Cipher Code Classical Cryptography Cryptanalysis Steganography References Classical ciphers Steganography