In classical cryptography, the running key cipher is a type of polyalphabetic substitution cipher in which a text, typically from a book, is used to provide...

substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the "units"...

book cipher is a cipher in which each word or letter in the plaintext of a message is replaced by some code that locates it in another text, the key. A...

intercepts two messages encrypted with the same key, they can recover A xor B, which is a form of running key cipher. Even if neither message is known, as long...

encoded with a different Caesar cipher, whose increment is determined by the corresponding letter of another text, the key. For example, if the plaintext...

same key. Block ciphers may be capable of operating on more than one block size, but during transformation the block size is always fixed. Block cipher modes...

of one-time pad ciphers have been used by nations for critical diplomatic and military communication, but the problems of secure key distribution make...

value of a letter from a companion ciphertext in a running key cipher, a constant for a Caesar cipher, or a zero-based counter with some period in Trithemius's...

An autokey cipher (also known as the autoclave cipher) is a cipher that incorporates the message (the plaintext) into the key. The key is generated from...

cryptography, a block cipher is a deterministic algorithm that operates on fixed-length groups of bits, called blocks. Block ciphers are the elementary building...

pigpen cipher (alternatively referred to as the masonic cipher, Freemason's cipher, Rosicrucian cipher, Napoleon cipher, and tic-tac-toe cipher) is a geometric...

with 30,000 random additives. The book used in a book cipher or the book used in a running key cipher can be any book shared by sender and receiver and is...

In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code, or Caesar shift, is one of the simplest and most widely...

for encryption is the cipher key, and it should be chosen randomly from the set of invertible n × n matrices (modulo 26). The cipher can, of course, be adapted...

The Playfair cipher or Playfair square or Wheatstone–Playfair cipher is a manual symmetric encryption technique and was the first literal digram substitution...

In cryptography, a transposition cipher (also known as a permutation cipher) is a method of encryption which scrambles the positions of characters (transposition)...

The Enigma machine is a cipher device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication...

The Two-square cipher, also called double Playfair, is a manual symmetric encryption technique. It was developed to ease the cumbersome nature of the large...

stream cipher and later co-invented an automated one-time pad cipher. Vernam proposed a teleprinter cipher in which a previously prepared key, kept on...

The four-square cipher is a manual symmetric encryption technique. It was invented by the French cryptographer Felix Delastelle. The technique encrypts...

In cryptography, the ADFGVX cipher was a manually applied field cipher used by the Imperial German Army during World War I. It was used to transmit messages...

In cryptography, a classical cipher is a type of cipher that was used historically but for the most part, has fallen into disuse. In contrast to modern...

cryptography, a Feistel cipher (also known as Luby–Rackoff block cipher) is a symmetric structure used in the construction of block ciphers, named after the...

polyalphabetic cipher is a substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though...

only one way to perform this, the Atbash cipher provides no communications security, as it lacks any sort of key. If multiple collating orders are available...

The rail fence cipher (also called a zigzag cipher) is a classical type of transposition cipher. It derives its name from the manner in which encryption...

In cryptography, key size or key length refers to the number of bits in a key used by a cryptographic algorithm (such as a cipher). Key length defines the...

cryptosystems. Before the mid-1970s, all cipher systems used symmetric key algorithms, in which the same cryptographic key is used with the underlying algorithm...

The VIC cipher was a pencil and paper cipher used by the Soviet spy Reino Häyhänen, codenamed "VICTOR". If the cipher were to be given a modern technical...

The Beale ciphers are a set of three ciphertexts, one of which allegedly states the location of a buried treasure of gold, silver and jewels estimated...