IDEA An encryption round of IDEA  Designer(s):  James Massey, Xuejia Lai  First published:  1991  Derived from:  PES  Successor(s):  MESH, Akelarre, IDEA NXT (FOX)  Key size(s):  128 bits  Block size(s):  64 bits  Structure:  Substitutionpermutation network  Rounds:  8.5  Best public cryptanalysis:  A collision attack requiring 2^{24} chosen plaintexts breaks 5 rounds with a complexity of 2^{126} (Demirci et al, 2003).   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. The algorithm was intended as a replacement for the Data Encryption Standard. IDEA is a minor revision of an earlier cipher, PES (Proposed Encryption Standard); IDEA was originally called IPES (Improved PES). Image File history File links Download high resolution version (640x658, 56 KB)Original diagram for Wikipedia File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
In cryptography, MESH is a block cipher designed in 2002 by Jorge Nakahara, Jr. ...
Akelarre can mean: a place in Navarre, Spain that gave its name to the meeting places of witches: see Akelarre, Navarre a block cipher: see Akelarre (cipher) This is a disambiguation page: a list of articles associated with the same title. ...
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 key size (alternatively key length) is a measure of the number of possible keys which can be used in a cipher. ...
In modern cryptography, symmetric key ciphers are generally divided into stream ciphers and block ciphers. ...
In cryptography, an SPnetwork, or substitutionpermutation network (SPN), is a series of linked mathematical operations used in block cipher algorithms such as AES. These networks consist of Sboxes and Pboxes that transform blocks of input bits into output bits. ...
Cryptanalysis (from the Greek kryptÃ³s, hidden, and analÃ½ein, 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. ...
A chosen plaintext attack is any form of cryptanalysis which presumes that the attacker has the capability to choose arbitrary plaintexts to be encrypted and obtain the corresponding ciphertexts. ...
The German Lorenz cipher machine, used in World War II for encryption of very highlevel general staff messages Cryptography (or cryptology; derived from Greek ÎºÏÏ…Ï€Ï„ÏŒÏ‚ kryptÃ³s hidden, and Î³ÏÎ¬Ï†ÎµÎ¹Î½ grÃ¡fein to write) is the study of message secrecy. ...
Encryption Decryption In cryptography, a block cipher is a symmetric key cipher which operates on fixedlength groups of bits, termed blocks, with an unvarying transformation. ...
The ETH Zurich, often called Swiss Federal Institute of Technology, is a science and technology university in the city of Zurich, Switzerland. ...
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. ...
This article is about algorithms for encryption and decryption. ...
The cipher was designed under a research contract with the Hasler Foundation, which became part of AscomTech AG. The cipher is patented in a number of countries but is freely available for noncommercial use. The name "IDEA" is also a trademark. The patents will expire in 2010–2011. Today, IDEA is licensed worldwide by MediaCrypt. A trademark, trade mark, â„¢ or Â®[1] is a distinctive sign of some kind which is used by an organization to uniquely identify itself and its products and services to consumers, and to distinguish the organization and its products or services from those of other organizations. ...
A patent is a set of exclusive rights granted by a state to a patentee (the inventor or assignee) for a fixed period of time in exchange for the regulated, public disclosure of certain details of a device, method, process or composition of matter (substance) (known as an invention) which...
IDEA was used in Pretty Good Privacy (PGP) V2.0, and was incorporated after the original cipher used in v1.0 ("BassOMatic") was found to be insecure. It is an optional algorithm in OpenPGP. PGP Encryption (Pretty Good Privacy) is a computer program which provides cryptographic privacy and authentication. ...
An Open Specification for Pretty Good Privacy (openpgp) OpenPGP is defined by the OpenPGP Working Group of the Internet Engineering Task Force (IETF) Proposed Standard RFC 2440. ...
Operation
IDEA operates on 64bit blocks using a 128bit key, and consists of a series of eight identical transformations (a round, see the illustration) and an output transformation (the halfround). The processes for encryption and decryption are similar. IDEA derives much of its security by interleaving operations from different groups — modular addition and multiplication, and bitwise eXclusive OR (XOR) — which are algebraically "incompatible" in some sense. In more detail, these operators, which all deal with 16bit quantities, are: In modern cryptography, symmetric key ciphers are generally divided into stream ciphers and block ciphers. ...
A key is a piece of information that controls the operation of a cryptography algorithm. ...
In mathematics, a group is a set, together with a binary operation, such as multiplication or addition, satisfying certain axioms, detailed below. ...
Modular arithmetic (sometimes called modulo arithmetic) is a system of arithmetic for integers, where numbers wrap around after they reach a certain value â€” the modulus. ...
Exclusive disjunction (usual symbol xor) is a logical operator that results in true if one of the operands (not both) is true. ...
 Bitwise eXclusive OR (denoted with a blue ⊕).
 Addition modulo 2^{16} (denoted with a green
).
 Multiplication modulo 2^{16}+1, where the allzero word (0x0000) is interpreted as 2^{16} (denoted by a red
).
After the eight rounds have been completed the logic of the output transformation shown below: Exclusive disjunction (usual symbol xor) is a logical operator that results in true if one of the operands (not both) is true. ...
a LaTeX boxplus File links The following pages link to this file: International Data Encryption Algorithm MD5 Categories: Usercreated public domain images ...
Image File history File links a LaTeX odot File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Image File history File links International_Data_Encryption_Algorithm_InfoBox_Diagram_Output_Trans. ...
Security The designers analysed IDEA to measure its strength against differential cryptanalysis and concluded that it is immune under certain assumptions. No successful linear or algebraic weaknesses have been reported. Some classes of weak keys have been found — E.g. (Daemen et al, 1994) — but these are of little concern in practice, being so rare as to be unnecessary to avoid explicitly. As of 2004, the best attack which applies to all keys can break IDEA reduced to 5 rounds (the full IDEA cipher uses 8.5 rounds) (Demirci et al, 2003). 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. ...
In cryptography, a weak key is a key which when used with a specific cipher, makes the cipher behave in some undesirable way. ...
2004 is a leap year starting on Thursday of the Gregorian calendar. ...
IDEA is patented in Austria, France, Germany, Italy, Netherlands, Spain, Sweden, Switzerland, United Kingdom, (European patent EPB0482154), the United States (US patent #5,214,703) and Japan (JP 3225440). MediaCrypt is now also offering a successor to IDEA and focuses on its new cipher (official release on May 2005) IDEA NXT, which was previously called FOX. 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). ...
References  J. Daemen, R. Govaerts, and J. Vandewalle, Weak keys for IDEA, Crypto '93. pp224–231.
 Hüseyin Demirci, Erkan Türe, Ali Aydin Selçuk, A New Meet in the Middle Attack on The IDEA Block Cipher, 10th Annual Workshop on Selected Areas in Cryptography, 2003.
 Xuejia Lai and James L. Massey, A Proposal for a New Block Encryption Standard, EUROCRYPT 1990, pp389–404
 Xuejia Lai and James L. Massey and S. Murphy, Markov ciphers and differential cryptanalysis, Advances in Cryptology — Eurocrypt '91, SpringerVerlag (1992), pp17–38.
Joan Daemen (born 1965) is a Belgian cryptographer and one of the designers of Rijndael, the Advanced Encryption Standard (AES), together with Vincent Rijmen. ...
External links  RSA FAQ on Block Ciphers
 Mediacrypt homepage — IDEA licensor
 SCAN entry for IDEA
 Helger Lipmaa's links for IDEA
