In cryptography

Cryptography

Cryptography is the practice and study of techniques for secure communication in the presence of third parties...

, KHAZAD (xɑːˈzɑːd) is a block cipher

Block cipher

In cryptography, a block cipher is a symmetric key cipher operating on fixed-length groups of bits, called blocks, with an unvarying transformation. A block cipher encryption algorithm might take a 128-bit block of plaintext as input, and output a corresponding 128-bit block of ciphertext...

 designed by Paulo S. L. M. Barreto

Paulo S. L. M. Barreto

Paulo S. L. M. Barreto is a Brazilian cryptographer and one of the designers of the Whirlpool hash function and the block ciphers Anubis and KHAZAD, together with Vincent Rijmen...

 together with Vincent Rijmen

Vincent Rijmen

Vincent Rijmen is a Belgian cryptographer and one of the two designers of the Rijndael, the Advanced Encryption Standard. Rijmen is also the co-designer of the WHIRLPOOL cryptographic hash function, and the block ciphers Anubis, KHAZAD, Square, NOEKEON and SHARK.In 1993, Rijmen obtained a degree...

, one of the designers of the Advanced Encryption Standard

Advanced Encryption Standard

Advanced Encryption Standard is a specification for the encryption of electronic data. It has been adopted by the U.S. government and is now used worldwide. It supersedes DES...

 (Rijndael). KHAZAD is named after Khazad-dûm

Moria (Middle-earth)

In the fiction of J. R. R. Tolkien, Moria was the name given by the Eldar to an enormous underground complex in north-western Middle-earth, comprising a vast network of tunnels, chambers, mines and huge halls or 'mansions', that ran under and ultimately through the Misty Mountains...

, the fictional dwarven

Dwarf (Middle-earth)

In the fiction of J. R. R. Tolkien, the Dwarves are a race inhabiting the world of Arda, a fictional prehistoric Earth which includes the continent Middle-earth....

 realm in the writings of J. R. R. Tolkien

J. R. R. Tolkien

John Ronald Reuel Tolkien, CBE was an English writer, poet, philologist, and university professor, best known as the author of the classic high fantasy works The Hobbit, The Lord of the Rings, and The Silmarillion.Tolkien was Rawlinson and Bosworth Professor of Anglo-Saxon at Pembroke College,...

 (see also Khazad

KHAZAD

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 . KHAZAD is named after Khazad-dûm, the fictional dwarven realm in the writings of J. R. R. Tolkien...

). KHAZAD was presented at the first NESSIE

NESSIE

NESSIE was a European research project funded from 2000–2003 to identify secure cryptographic primitives. The project was comparable to the NIST AES process and the Japanese Government-sponsored CRYPTREC project, but with notable differences from both...

 workshop in 2000, and, after some small changes, was selected as a finalist in the project.

KHAZAD has an eight-round substitution-permutation network

Substitution-permutation network

In cryptography, an SP-network, or substitution-permutation network , is a series of linked mathematical operations used in block cipher algorithms such as AES .Other ciphers that use SPNs are 3-Way, SAFER, SHARK, and Square....

 structure similar to that of SHARK, a forerunner to Rijndael. The design is classed as a "legacy-level" algorithm, with a 64-bit block size

Block size (cryptography)

In modern cryptography, symmetric key ciphers are generally divided into stream ciphers and block ciphers. Block ciphers operate on a fixed length string of bits. The length of this bit string is the block size...

 (in common with older cipher

Cipher

In cryptography, a cipher 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. In non-technical usage, a “cipher” is the same thing as a “code”; however, the concepts...

s such as DES

Data Encryption Standard

The Data Encryption Standard is a block cipher that uses shared secret encryption. It was selected by the National Bureau of Standards as an official Federal Information Processing Standard for the United States in 1976 and which has subsequently enjoyed widespread use internationally. It is...

 and IDEA) and a 128-bit key

Key (cryptography)

In cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would produce no useful result. In encryption, a key specifies the particular transformation of plaintext into ciphertext, or vice versa...

. KHAZAD makes heavy use of involutions as subcomponents; this minimises the difference between the algorithms for encryption

Encryption

In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...

 and decryption.

The authors have stated that, "KHAZAD is not (and will never be) patent

Patent

A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

ed. It may be used free of charge for any purpose."

Frédérik Muller has discovered an attack which can break five of KHAZAD's eight rounds. No attacks better than this are known as of August 2009.

External links

• KHAZAD home page