Writing systems

Usage examples of alphabets.

The monoalphabetically enciphered letters that are the goal of these techniques also exist in a Vernam one-time system cryptogram because the 32 available cipher alphabets are used over and over again.

There are as many of these alphabets as there are positions of his disk, and this multiplicity means that Alberti here devised the first polyalphabetic cipher.

For example, if a polyalphabetic cipher provides 26 cipher alphabets, a keyword might define the half dozen or so that are to be used in a particular message.

Before they were executed, the authorities prudently extracted from Babington the cipher alphabets he had used with Mary.

This is the elemental form of polyalphabetic substitution, for it exhibits all at once all the cipher alphabets in a particular system.

In this particular message, he switched to another alphabet after 24 letters, but in another example he followed the more normal procedure of repeating the alphabets over and over again in groups of 24.

The system permits great flexibility: no longer did all messages have to be enciphered with one of a relatively few standard sequences of alphabets, but different ambassadors could be given individual keys, and, if it were feared that a key had been stolen or solved, a new one could be substituted with the greatest of ease.

Its tableau consists of a modern tabula recta: 26 standard horizontal alphabets, each slid one space to the left of the one above.

Another normal alphabet, which merely repeats the initial letters of the horizontal ciphertext alphabets, runs down the left side.

Now, knowledge of how many letters are in the keyword tells how many alphabets were used in the polyalphabetic encipher-ment.

Its author had the instinct for the cryptographic jugular, and he compressed into 64 pages virtually the entire known field of cryptology, including polyalphabetics with mixed alphabets, enciphered code, and cipher devices.

With few exceptions, it lays no restrictions on the type or length of keys, as does the Kasiski method, nor on the alphabets, which may be interrelated or entirely independent.

Because the Baudot alphabet is public information, the composition of the 32 cipher alphabets filling the body of the tableau would be known.

The rotor thus will produce as many cipher alphabets as it has positions, usually 26.

If each rotor turns a space only when the preceding rotor has completed a revolution, the number of alphabets that the array of rotors creates will equal the product of the number of positions that each rotor can take.