Cipher disk

One of the first devices to encrypt was the cipher. These are two round metal discs that sit on a common axis and are connected so that the minor can turn on the larger. Slices of this type has been around since the 15th century. The development of the first cipher is attributed to Leon Battista Alberti.

At the outer edge of the discs in each case different alphabets or symbols are shown. By turning the wheels against each other to move these alphabets, which is used for encryption. For example, if the inner B under the outer A is (unlike the picture), then this corresponds to a shift cipher for a job, and you can about the inner plaintext letters outside the ciphertext letters (or, as in this picture, the secret symbol, for example, " 8818 " ) read. The outer disk contains the ciphertext and the inner the plaintext alphabet here.

So can be after a single setting of the discs very easily achieve a monoalphabetic encryption, or if you change the position of the discs to each other during the encryption, even a polyalphabetic encryption.

41370
de