Media Contributed by Rick
First page of On Deciphering Cryptographic Messages The first page of al-Kindi's manuscript On Deciphering Cryptographic Messages, containing the oldest known description of cryptanalysis by frequency analysis.
Caesar cipher diagram The action of a Caesar cipher is to replace each plaintext letter with a different one a fixed number of places down the alphabet. The cipher illustrated here uses a left shift of three, so that (for example) each occurrence of E in the plaintext becomes B in the ciphertext.
Suetonius, De vita Caesarum Berlin State Library (Ms. lat. fol. 28, fol. 73v.)
Caesar cipher mechanism A construction of two rotating disks with a Caesar cipher can be used to encrypt or decrypt the code
