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Encyclopedia > Key schedule
The key-schedule of DES ("<<<" denotes a left rotation)
The key-schedule of DES ("<<<" denotes a left rotation)

In cryptography, the so-called product ciphers are a certain kind of ciphers, where the (de-)ciphering of data is done in "rounds". The general setup of each round is the same, except for some hard-coded parameters and a part of the cipher key, called a subkey. A key schedule is an algorithm that, given the key, calculates the subkeys for these rounds. Key schedule of DES This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Key schedule of DES This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... The German Lorenz cipher machine, used in World War II for encryption of very high-level general staff messages Cryptography (or cryptology; derived from Greek κρυπτός kryptós hidden, and the verb γράφω gráfo write) is the study of message secrecy. ... In cryptography, a product cipher is a popular type of block cipher that works by executing in sequence a number of simple transformations such as substitution, permutation, and modular arithmetic. ... A key is a piece of information that controls the operation of a cryptography algorithm. ...

Contents

Some types of key schedules

  • Some ciphers have simple key schedules. For example, the block cipher TEA simply splits the 128-bit key into four 32-bit pieces and uses them repeatedly in successive rounds.
  • DES uses a key schedule where the 56 bit key is divided into two 28-bit halves; each half is thereafter treated separately. In successive rounds, both halves are rotated left by one or two bits (specified for each round), and then 48 subkey bits are selected by Permuted Choice 2 (PC-2) — 24 bits from the left half, and 24 from the right. The rotations mean that a different set of bits is used in each subkey; each bit is used in approximately 14 out of the 16 subkeys.
  • In an effort to avoid simple relationships between the cipher key and the subkeys, many modern ciphers use much more elaborate key schedules, algorithms that use a one-way function to generate an "expanded key" from which subkeys are drawn. Some ciphers, such as Rijndael (AES) and Blowfish, use parts of the cipher algorithm itself for this key expansion, sometimes initialized with some "nothing up my sleeve numbers". Other ciphers, such as RC5, expand keys with functions that are somewhat or completely different from the encryption functions.

General Designer(s) Roger Needham and David Wheeler First published 1994 Derived from - Cipher(s) based on this design XTEA Algorithm detail Block size(s) 64 bits Key size(s) 128 bits Structure Feistel network Number of rounds variable; recommended 64 Feistel rounds; 32 cycles Best cryptanalysis TEA suffers from... The Data Encryption Standard (DES) is a cipher (a method for encrypting information) selected as an official Federal Information Processing Standard (FIPS) for the United States in 1976, and which has subsequently enjoyed widespread use internationally. ... Unsolved problems in computer science: Do one-way functions exist? A one-way function is a function that is easy to compute but hard to invert. ... This article or section is in need of attention from an expert on the subject. ... General Designer(s) Bruce Schneier First published 1993 Derived from - Cipher(s) based on this design Twofish Algorithm detail Block size(s) 64 bits Key size(s) 32-448 bits in steps of 8 bits; default 128 bits Structure Feistel network Number of rounds 16 Best cryptanalysis Four rounds of... Nothing up my sleeve numbers are the the opposite extreme of Chaitin-Kolmogorov randomness in that they appear to be random by statistical tests but are created with minimum entropy. ... RC5 is a block cipher notable for its simplicity. ...

Notes

Knudsen and Mathiassen (2004) give some experimental evidence that indicate that the key schedule plays a part in providing strength against linear and differential cryptanalysis. For toy Feistel ciphers, it was observed that those with complex and well-designed key schedules can reach a uniform distribution for the probabilities of differentials and linear hulls faster than those with poorly-designed key schedules. Lars R. Knudsen Lars Ramkilde Knudsen (born February 21, 1962) is a Danish researcher in cryptography, particularly interested in the design and analysis of block ciphers, hash functions and message authentication codes (MACs). ... In cryptography, linear cryptanalysis is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. ... Differential cryptanalysis is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. ... Feistel cipher - Wikipedia /**/ @import /skins-1. ... Differential cryptanalysis is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. ... In cryptography, linear cryptanalysis is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. ...


See also

In cryptography, a related-key attack is any form of cryptanalysis where the attacker can observe the operation of a cipher under several different keys whose values are initially unknown, but where some mathematical relationship connecting the keys is known to the attacker. ...

References

  • Lars R. Knudsen and John Erik Mathiassen, On the Role of Key Schedules in Attacks on Iterated Ciphers, ESORICS 2004, pp322–334.
Block ciphers
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Algorithms: 3-Way | AES | Akelarre | Anubis | ARIA | BaseKing | Blowfish | C2 | Camellia | CAST-128 | CAST-256 | CIKS-1 | CIPHERUNICORN-A | CIPHERUNICORN-E | CMEA | Cobra | COCONUT98 | Crab | CRYPTON | CS-Cipher | DEAL | DES | DES-X | DFC | E2 | FEAL | FROG | G-DES | GOST | Grand Cru | Hasty Pudding Cipher | Hierocrypt | ICE | IDEA | IDEA NXT | Iraqi | Intel Cascade Cipher | KASUMI | KHAZAD | Khufu and Khafre | KN-Cipher | Libelle | LOKI89/91 | LOKI97 | Lucifer | M6 | MacGuffin | Madryga | MAGENTA | MARS | Mercy | MESH | MISTY1 | MMB | MULTI2 | NewDES | NOEKEON | NUSH | Q | RC2 | RC5 | RC6 | REDOC | Red Pike | S-1 | SAFER | SC2000 | SEED | Serpent | SHACAL | SHARK | Skipjack | SMS4 | Square | TEA | Triple DES | Twofish | UES | Xenon | xmx | XTEA | Zodiac
Design: Feistel network | Key schedule | Product cipher | S-box | SPN

Attacks: Brute force | Linear / Differential / Integral cryptanalysis | Mod n | Related-key | Slide | XSL Encryption Decryption In cryptography, a block cipher is a symmetric key cipher which operates on fixed-length groups of bits, termed blocks, with an unvarying transformation. ... In cryptography, 3-Way is a block cipher designed in 1994 by Joan Daemen, who also (with Vincent Rijmen) designed Rijndael, the winner of NISTs Advanced Encryption Standard (AES) contest. ... In cryptography, the Advanced Encryption Standard (AES), also known as Rijndael, is a block cipher adopted as an encryption standard by the U.S. government. ... Akelarre is a block cipher proposed in 1996, and combined features from IDEA and RC5. ... Anubis is a block cipher designed by Vincent Rijmen and Paulo S. L. M. Barreto as an entrant in the NESSIE project. ... In cryptography, ARIA is a block cipher designed in 2003 by a large group of Korean researchers. ... In cryptography, BaseKing is a block cipher designed in 1994 by Joan Daemen. ... General Designer(s) Bruce Schneier First published 1993 Derived from - Cipher(s) based on this design Twofish Algorithm detail Block size(s) 64 bits Key size(s) 32-448 bits in steps of 8 bits; default 128 bits Structure Feistel network Number of rounds 16 Best cryptanalysis Four rounds of... The Cryptomeria cipher, commonly refered to as C2 is a proprietary block cipher defined and licensed by the 4C Entity. ... In cryptography, Camellia is a block cipher that has been evaluated favorably by several organisations, including the European Unions NESSIE project (a selected algorithm), and the Japanese CRYPTREC project (a recommended algorithm). ... Three rounds of the CAST-128 block cipher In cryptography, CAST-128 (alternatively CAST5) is a block cipher used in a number of products, notably as the default cipher in some versions of GPG and PGP. It has also been approved for Canadian government use by the Communications Security Establishment. ... In cryptography, CAST-256 (or CAST6) is a block cipher published in June 1998 and submitted as a candidate for the Advanced Encryption Standard (AES). ... In cryptography, CIKS-1 is a block cipher designed in 2002 by A.A. Moldovyan and N.A. Moldovyan. ... In cryptography, CIPHERUNICORN-A is a block cipher created by NEC in 2000. ... In cryptography, CIPHERUNICORN-E is a block cipher created by NEC in 1998. ... In cryptography, the Cellular Message Encryption Algorithm (CMEA) is a block cipher which was used for securing mobile phones in the United States. ... In cryptography, Cobra is the general name of a family of data-dependent permutation based block ciphers: Cobra-128, Cobra-F64a, Cobra-F64b, Cobra-H64 and Cobra-H128. ... In cryptography, COCONUT98 (Cipher Organized with Cute Operations and N-Universal Transformation) is a block cipher designed by Serge Vaudenay in 1998. ... In cryptography, Crab is a block cipher created by Burt Kaliski and Matt Robshaw in 1993. ... In particle physics, the crypton is a hypothetical superheavy particle, thought to exist in a hidden sector of string theory. ... In cryptography, the CS-Cipher is a block cipher invented by Jacques Stern and Serge Vaudenay in 1998. ... Deal can refer to: an agreement reached after negotiation, for example a contract to sell as a dealer or dealership a bargain a situation, as in whats the deal with the Johnson account ?. a problem, as in whats your deal ?. Deal$, a U.S. dollar store a Deal... The Data Encryption Standard (DES) is a cipher (a method for encrypting information) selected as an official Federal Information Processing Standard (FIPS) for the United States in 1976, and which has subsequently enjoyed widespread use internationally. ... In cryptography, DES-X (or DESX) is a variant on the DES (Data Encryption Standard) block cipher intended to increase the complexity of a brute force attack using a technique called key whitening. ... In cryptography, DFC (Decorrelated Fast Cipher) is a block cipher which was created in 1998 by a group of researchers at École Normale Supérieure and submitted to the AES competition. ... In cryptography, E2 is a block cipher which was created in 1998 by NTT and submitted to the AES competition. ... General Designer(s) Akihiro Shimizu and Shoji Miyaguchi (NTT) First published FEAL-4 in 1987; FEAL-N/NX in 1990 Derived from - Cipher(s) based on this design - Algorithm detail Block size(s) 64 bits Key size(s) 64 bits (128 bits for FEAL-NX) Structure Feistel network Number of... Distribution of frogs (in black) Suborders Archaeobatrachia Mesobatrachia Neobatrachia - List of Anuran families The frog is an amphibian in the order Anura (meaning tail-less from Greek an-, without + oura, tail), formerly referred to as Salientia (Latin saltare, to jump). ... In cryptography, the Generalized DES Scheme (G-DES or GDES) is a variant of the DES block cipher designed to speed-up the encryption. ... Diagram of GOST In cryptography, GOST (Russian ГОСТ) (GOsudarstvennyi STandard, Russian for Government Standard) is a symmetric key block cipher published in 1990 as the Soviet standard (GOST 28147-89). ... In cryptography, Grand Cru is a block cipher invented in 2000 by Johan Borst. ... The Hasty Pudding Cipher (abbreviated HPC) is a variable-block-size block cipher which was an unsuccessful candidate in the competition for selecting the U.S. Advanced Encryption Standard. ... In cryptography, Hierocrypt-L1 and Hierocrypt-3 are block ciphers created by Toshiba in 2000. ... General Designer(s) Matthew Kwan First published 1997 Derived from (DES) Cipher(s) based on this design - Algorithm detail Block size(s) 64 bits Key size(s) 64 bits for ICE, 64n for ICE-n Structure Feistel network Number of rounds 16 for ICE, 8 for Thin-ICE, 16n for... In cryptography, the International Data Encryption Algorithm (IDEA) is a block cipher designed by Xuejia Lai (來學嘉) and James L. Massey of ETH Zurich and was first described in 1991. ... In cryptography, the IDEA NXT algorithm (previously known as FOX) is a block cipher designed by Pascal Junod and Serge Vaudenay of EPFL (Lausanne, Switzerland). ... In cryptography, the Intel Cascaded Cipher, is a relatively new, high bandwidth block cipher, used as an optional component of the Output Content Protection DRM scheme of the Microsoft Windows Vista operating system. ... In cryptography, KASUMI, also termed A5/3, is a block cipher used in the confidentiality (f8) and integrity algorithms (f9) for 3GPP mobile communications. ... In cryptography, KHAZAD is a block cipher designed by Paulo S. L. M. Barreto together with Vincent Rijmen, one of the designers of the Advanced Encryption Standard (Rijndael). ... In cryptography, Khufu and Khafre are two block ciphers designed by Ralph Merkle in 1989 while working at Xeroxs Palo Alto Research Center. ... In cryptography, KN-Cipher is a block cipher created by Kaisa Nyberg and Lars Knudsen in 1995. ... Libelle is a German cipher system, developed by the Federal Office for Information Security. ... It has been suggested that Loki and the dwarfs be merged into this article or section. ... In cryptography, LOKI97 is a block cipher which was a candidate in the Advanced Encryption Standard competition. ... In cryptography, Lucifer was the name given to several of the earliest civilian block ciphers, developed by Horst Feistel and his colleagues at IBM. Lucifer was a direct precursor to the Data Encryption Standard. ... In cryptography, M6 is a block cipher proposed by Hitachi in 1997 for use in the IEEE 1394 FireWire standard. ... In cryptography, MacGuffin is a block cipher created in 1994 by Bruce Schneier and Matt Blaze at a Fast Software Encryption workshop. ... In cryptography, Madryga is a block cipher created in 1984 by W. E. Madryga. ... Magenta is a color made up of equal parts of red and blue light. ... Adjectives: Martian Atmosphere Surface pressure: 0. ... In cryptography, Mercy is a block cipher designed by Paul Crowley for disk encryption. ... In cryptography, MESH is a block cipher designed in 2002 by Jorge Nakahara, Jr. ... In cryptography, MISTY1 (or MISTY-1) is a block cipher designed in 1995 by Mitsuru Matsui and others for Mitsubishi Electric. ... In cryptography, MMB (Modular Multiplication-based Block cipher) is a block cipher designed by Joan Daemen as an improved replacement for the IDEA cipher. ... MULTI2 is a block cipher, developed by Hitachi in 1988. ... In cryptography, NewDES is a symmetric key block cipher. ... Noekeon is a block cipher with a block and key length of 128 bits. ... In cryptography, NUSH is a block cipher invented by Anatoly Lebedev and Alexey Volchkov for LAN Crypto, a Russian company. ... In cryptography, Q is a block cipher invented by Leslie McBride. ... In cryptography, RC2 is a block cipher designed by Ron Rivest in 1987. ... RC5 is a block cipher notable for its simplicity. ... In cryptography, RC6 is a symmetric key block cipher derived from RC5. ... In cryptography, REDOC II and REDOC III are block ciphers designed by Michael Wood for Cryptech Inc and are optimised for use in software. ... Red Pike is a classified United Kingdom government cipher, proposed for use by the National Health Service by GCHQ, but designed for a broad range of applications in the British government [1]. Little is publicly known about Red Pike, except that it is a block cipher with a 64-bit... Uplandia Regiment, or Upplands regemente, also S 1, is a Swedish Army signaling regiment that traces its origins back to the 19th Century. ... This article is about the encryption algorithm. ... In cryptography, SC2000 is a block cipher invented by a research group at Fujitsu Labs. ... A ripe red jalapeño cut open to show the seeds For other uses, see Seed (disambiguation). ... Serpent is a symmetric key block cipher which was a finalist in the Advanced Encryption Standard contest, where it came second to Rijndael. ... SHACAL-1 and SHACAL-2 are block ciphers based on cryptographic hash function from the SHA family. ... Orders Carcharhiniformes Heterodontiformes Hexanchiformes Lamniformes Orectolobiformes Pristiophoriformes Squaliformes Squatiniformes Symmoriida(extinct) Shark (superorder Selachimorpha) are fish with a full cartilaginous skeleton[1] and a streamlined body. ... In cryptography, Skipjack is a block cipher — an algorithm for encryption — developed by the U.S. National Security Agency (NSA). ... SMS4 is a block cipher used in Chinese National Standard for Wireless LAN WAPI (Wired Authentication and Privacy Infrastructure). ... In cryptography, Square (sometimes written SQUARE) is a block cipher invented by Joan Daemen and Vincent Rijmen. ... General Designer(s) Roger Needham and David Wheeler First published 1994 Derived from - Cipher(s) based on this design XTEA Algorithm detail Block size(s) 64 bits Key size(s) 128 bits Structure Feistel network Number of rounds variable; recommended 64 Feistel rounds; 32 cycles Best cryptanalysis TEA suffers from... In cryptography, Triple DES (also 3DES) is a block cipher formed from the Data Encryption Standard (DES) cipher. ... In cryptography, Twofish is a symmetric key block cipher with a block size of 128 bits and key sizes up to 256 bits. ... This article is about the block cipher. ... In cryptography, Xenon is a block cipher designed in 2000 by Chang-Hyi Lee for the Korean firm SoftForum. ... In cryptography, xmx is a block cipher designed in 1997 by David MRaïhi, David Naccache, Jacques Stern, and Serge Vaudenay. ... General Designer(s) Roger Needham and David Wheeler First published 1997 Derived from Tiny Encryption Algorithm (TEA) Cipher(s) based on this design - Algorithm detail Block size(s) 64 bits Key size(s) 128 bits Structure Feistel network Number of rounds variable; recommended 64 Feistel rounds; 32 cycles Best cryptanalysis... In cryptography, Zodiac is a block cipher designed in 2000 by Chang-Hyi Lee for the Korean firm SoftForum. ... Feistel cipher - Wikipedia /**/ @import /skins-1. ... In cryptography, a product cipher is a popular type of block cipher that works by executing in sequence a number of simple transformations such as substitution, permutation, and modular arithmetic. ... In cryptography, a substitution box (or S-box) is a basic component of symmetric key algorithms. ... In cryptography, an SP-network, or substitution-permutation network (SPN), is a series of linked mathematical operations used in block cipher algorithms such as AES. These networks consist of S-boxes and P-boxes that transform blocks of input bits into output bits. ... The EFFs US$250,000 DES cracking machine contained over 1,800 custom chips and could brute force a DES key in a matter of days — the photograph shows a DES Cracker circuit board fitted with several Deep Crack chips. ... In cryptography, linear cryptanalysis is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. ... Differential cryptanalysis is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. ... In cryptography, integral cryptanalysis is a cryptanalytic attack that is particularly applicable to block ciphers based around Substitution-permutation networks. ... Cryptanalysis (from the Greek kryptós, hidden, and analýein, to loosen or to untie) is the study of methods for obtaining the meaning of encrypted information, without access to the secret information which is normally required to do so. ... In cryptography, mod n cryptanalysis is an attack applicable to block and stream ciphers. ... In cryptography, a related-key attack is any form of cryptanalysis where the attacker can observe the operation of a cipher under several different keys whose values are initially unknown, but where some mathematical relationship connecting the keys is known to the attacker. ... The idea of the slide attack was originally published by Edna Grossman and Bryant Tuckerman in an IBM Technical Report in 1977. ... New Scientist magazine featured the XSL attack in June 2003 with an article billed as Cipher crisis: the end of internet privacy. In cryptography, the XSL attack is a method of cryptanalysis for block ciphers. ...

Standardization: AES process | CRYPTREC | NESSIE

Misc: Avalanche effect | Block size | IV | Key size | Modes of operation | Piling-up lemma | Weak key The Advanced Encryption Standard (AES), the block cipher ratified as a standard by National Institute of Standards and Technology (NIST), was chosen using a process markedly more open and transparent than its predecessor, the ageing Data Encryption Standard (DES). ... CRYPTREC is the Cryptography Research and Evaluation Committee set up by the Japanese Government to evaluate and recommend cryptographic techniques for government and industrial use. ... NESSIE (New European Schemes for Signatures, Integrity and Encryption) was a European research project funded from 2000&#8211;2003 to identify secure cryptographic primitives. ... This article is about cryptography; for other meanings, see snowball effect. ... In modern cryptography, symmetric key ciphers are generally divided into stream ciphers and block ciphers. ... In cryptography, an initialization vector (IV) is a block of bits that is required to allow a stream cipher or a block cipher executed in any of several streaming modes of operation to produce a unique stream independent from other streams produced by the same encryption key, without having to... In cryptography, the key size (alternatively key length) is a measure of the number of possible keys which can be used in a cipher. ... In cryptography, a block cipher operates on blocks of fixed length, often 64 or 128 bits. ... In cryptanalysis, the piling-up lemma is a principle used in linear cryptanalysis to construct linear approximations to the action of block ciphers. ... In cryptography, a weak key is a key which when used with a specific cipher, makes the cipher behave in some undesirable way. ...

Cryptography
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History of cryptography | Cryptanalysis | Cryptography portal | Topics in cryptography
Symmetric-key algorithm | Block cipher | Stream cipher | Public-key cryptography | Cryptographic hash function | Message authentication code | Random numbers

  Results from FactBites:
 
Key (cryptography) - Wikipedia, the free encyclopedia (854 words)
Keys are also used in other cryptographic algorithms, such as digital signature schemes and keyed-hash functions (also known as MACs), often used for authentication.
A newer class of "public key" cryptographic algorithms was discovered in the 1970s which use a pair of keys, one to encrypt and one to decrypt.
When a password (or passphrase) is used as an encryption key, well-designed cryptosystems first run it through a key-derivation algorithm which adds salt and reduces or expands it to the key length desired, for example by reducing a long phrase into a 128-bit value suitable for use in a block cipher.
Key schedule - definition of Key schedule in Encyclopedia (173 words)
In cryptography, the algorithm for computing the subkeys for each round in a product cipher from the encryption (or decryption) key is called the key schedule.
For toy Feistel ciphers, it was observed that those with complex and well-designed key schedules can reach a uniform distribution for the probabilities of differentials and linear hulls faster than those with poorly-designed key schedules.
Lars R. Knudsen and John Erik Mathiassen, On the Role of Key Schedules in Attacks on Iterated Ciphers, ESORICS 2004, pp322–334.
  More results at FactBites »

 
 

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