cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...

, SOBER is a family of

stream cipher stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream (keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream ...

s initially designed by Greg Rose of QUALCOMM Australia starting in 1997. The name is a contrived acronym for ''S''eventeen ''O''ctet ''B''yte ''E''nabled ''R''egister. Initially the cipher was intended as a replacement for broken ciphers in cellular telephony. The ciphers evolved, and other developers (primarily Phillip Hawkes) joined the project. SOBER was the first cipher, with a 17-byte

linear-feedback shift register In computing, a linear-feedback shift register (LFSR) is a shift register whose input bit is a linear function of its previous state. The most commonly used linear function of single bits is exclusive-or (XOR). Thus, an LFSR is most often a sh ...

(LFSR), a form of

decimation Decimation, Decimate, or variants may refer to: * Decimation (punishment), punitive discipline * Decimation (signal processing), reduction of digital signal's sampling rate * Decimation (comics), 2006 Marvel crossover spinoff ''House of M'' * ''D ...

called ''stuttering'', and a nonlinear output filter function. The particular configuration of the shift register turned out to be vulnerable to "guess and determine" attacks. SOBER-2 changed the position of the feedback and output taps to resist the above attacks. S16 was an expansion to 16-bit words rather than bytes, with an expected increase of security.

Adaptions for and since NESSIE

For the

NESSIE NESSIE (New European Schemes for Signatures, Integrity and Encryption) was a European research project funded from 2000 to 2003 to identify secure cryptographic primitives. The project was comparable to the NIST AES process and the Japanese Gov ...

call for new cryptographic primitives, three new versions called the t-class were developed; SOBER-t8 was virtually identical to SOBER-2 but did not have sufficient design strength for NESSIE submission; SOBER-t16 and SOBER-t32 were submitted. t32 was a further expansion to 32-bit words, while both ciphers had a more efficient method of computing the linear feedback. Subsequent to NESSIE,

SOBER-128 SOBER-128 is a synchronous stream cipher designed by Hawkes and Rose (2003) and is a member of the SOBER family of ciphers. SOBER-128 was also designed to provide MAC (message authentication code) functionality. Watanabe and Furuya (2004) show ...

was designed to take into account what had been learned. The stuttering was dropped because it added too little strength for the overhead, and the nonlinear output function was strengthened. As a stream cipher, SOBER-128 remains unbroken. The message authentication capability that was added at the same time was trivially broken. ;Mundja: An integrated message authentication feature based on

SHA-256 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression ...

that was designed to be added to stream ciphers such as SOBER-128. ;

Turing Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalysis, cryptanalyst, philosopher, and mathematical and theoretical biology, theoretical biologist. Turing was high ...

: Named after

Alan Turing Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical com ...

, shares the LFSR design of SOBER-128, but has a block-cipher-like output filter function with key-dependent

S-box In cryptography, an S-box (substitution-box) is a basic component of symmetric key algorithms which performs substitution. In block ciphers, they are typically used to obscure the relationship between the key and the ciphertext, thus ensuring Sha ...

es, and remains unbroken subject to a minor usage constraint. ;NLS: Short for Non-Linear SOBER, it was submitted to the European

eSTREAM eSTREAM is a project to "identify new stream ciphers suitable for widespread adoption", organised by the EU ECRYPT network. It was set up as a result of the failure of all six stream ciphers submitted to the NESSIE project. The call for primiti ...

project. It uses nonlinearity for the shift register, and simplifies the output filter for increased performance, using Mundja for message authentication. SSS, for Self-Synchronizing SOBER, was also submitted but has very little relationship to the other SOBER ciphers, and was quickly broken. ;Shannon: Named after

Claude Shannon Claude Elwood Shannon (April 30, 1916 – February 24, 2001) was an American people, American mathematician, electrical engineering, electrical engineer, and cryptography, cryptographer known as a "father of information theory". As a 21-year-o ...

, shortens the register to 16 32-bit words, and has completely new feedback and output filter tap positions. It incorporates a new and more efficient message authentication mechanism. ;Boole: Named after

George Boole George Boole (; 2 November 1815 – 8 December 1864) was a largely self-taught English mathematician, philosopher, and logician, most of whose short career was spent as the first professor of mathematics at Queen's College, Cork in Ire ...

, is a family of combined

hash function A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called ''hash values'', ''hash codes'', ''digests'', or simply ''hashes''. The values are usually u ...

s and

stream ciphers stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream (keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, ...

that were developed for submission to the

NIST The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

call for development of an advanced hash standard, but were withdrawn when a collision was discovered.http://ehash.iaik.tugraz.at/uploads/0/0b/BooleCollision.txt

References

External links

QUALCOMM Australia
– info on the whole SOBER family

– NIST call for an Advanced Hash Standard {{Cryptography navbox , stream Stream ciphers