M6 (cipher)
In cryptography, M6 is a block cipher proposed by Hitachi in 1997 for use in the IEEE 1394 FireWire standard. The design allows some freedom in choosing a few of the cipher's operations, so M6 is considered a family of ciphers.
The algorithm operates on blocks of 64 bits using a 10-round Feistel network structure. The key size is 40 bits by default, but can be up to 64 bits. The key schedule is very simple, producing two 32-bit subkeys: the high 32 bits of the key, and the sum mod 232 of this and the low 32 bits.
Because its round function is based on rotation and addition, M6 was one of the first ciphers attacked by mod n cryptanalysis. Mod 5, about 100 known plaintexts suffice to distinguish the output from a pseudorandom permutation. Mod 257, information about the secret key itself is revealed. One known plaintext reduces the complexity of a brute force attack to about 235 trial encryptions; "a few dozen" known plaintexts lowers this number to about 231. Due to its simple key schedule, M6 is also vulnerable to a slide attack, which requires more known plaintext but less computation.
Cipher
In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment. To encipher or encode is to convert information into cipher or code. In common parlance, 'cipher' is synonymous with 'code', as they are both a set of steps that encrypt a message; however, the concepts are distinct in cryptography, especially classical cryptography.
Codes generally substitute different length strings of characters in the output, while ciphers generally substitute the same number of characters as are input. There are exceptions and some cipher systems may use slightly more, or fewer, characters when output versus the number that were input.
Codes operated by substituting according to a large codebook which linked a random string of characters or numbers to a word or phrase. For example, "UQJHSE" could be the code for "Proceed to the following coordinates." When using a cipher the original information is known as plaintext, and the encrypted form as ciphertext. The ciphertext message contains all the information of the plaintext message, but is not in a format readable by a human or computer without the proper mechanism to decrypt it.
Cipher (disambiguation)
A cipher is a method of encryption or decryption.
Cipher may also refer to:
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Cipher (newuniversal)
Cipher (Jennifer Swann) is a fictional character appearing in American comic books published by Marvel Comics. The character appears in the newuniversal imprint of Marvel Comics, and is one of the four initial superhumans created by the White Event in 2006 (the others being Justice, Nightmask, and Star Brand). newuniversal, designated Earth-555 in the Marvel Comics multiverse, is a re-imagining of the New Universe imprint from the late 1980s. The name Cipher actually refers to two things: a powerful extra-dimensional glyph (tattoo) that confers superhuman powers on a sentient being, and the name of the being that wields the glyph. Cipher is a new superhuman created by Warren Ellis and Salvador Larroca who were inspired by the original Spitfire and the nature of the Star Brand itself (as an extra-dimensional tool of near-unlimited power), combined with strong conceptual ties to Iron Man.
Fictional character biography
Project Spitfire
Essentially nothing is known about Dr. Jennifer Swann’s early life, or where she earned her doctorate. Sometime in the late 1990s or early 2000s she was hired by the NSA to work on Project Spitfire, taking her father’s previous position there. Jennifer continues the work her father, Dr. Joseph Swann, began in 1959 on the H.E.X. (Human Enhancement eXperimental) initiative, an armored exoskeleton that is intended to enable its wearer to combat superhumans with a wide variety of weapons. The original suit was created by Anthony Stark in 1959 who became Cipher in the "The Fireworks" event in 1955, and is an alternate version of Tony Stark (Iron Man) from the mainstream Marvel Universe. Prior to the events in newuniversal #1, neither Jennifer nor her father were able to perfect the design, both suffering broken bones during testing.
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