This option is supported for encoding as well. The technique encrypts pairs of letters (digraphs), instead of single letters as in the simple substitution cipher. It was invented in 1854 by Charles Wheatstone but was named after Lord Playfair who promoted the use of the cipher. Traditionally, punctuation and spaces are removed to disguise word boundaries and text is written in blocks of letters, usually five. The Playfair cipher was the first practical digraph substitution cipher. Paste text into the field, fill the key, choose 'encode' if you have pasted clear text or 'decode' if you have pasted ciphered text, and press 'Calculate'. The cipher does not change language letter frequencies (it is said to be monoalphabetic), unlike, for example, the polyalphabetic Vigenère cipher, so it is considered to be rather weak. However, you can break it if you have enough ciphered text by using frequency analysis or the stochastic optimization algorithm (check out our Substitution cipher decoder). The number of all possible keys for a simple substitution cipher is a factorial of 26 (26!). This means that A is replaced with C, B with D, and so on. For example, its ROT2 key can be presented as CDEFGHIJKLMNOPQRSTUVWXYZAB. The Caesar cipher is a form of a simple substitution cipher. Now, this 5x5 grid of matrix consists of alphabets(a-z) which is used to encrypt/decrypt the text. The substitution key is usually represented by writing out the alphabet in some order. The receiver deciphers the text by performing the inverse substitution.Ī simple substitution is the substitution of single letters separately. According to Wikipedia, in cryptography, a substitution cipher is a method of encrypting by which units of plaintext are replaced with ciphertext, according to a fixed system the 'units' may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth.

Playfair cipher tool