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 ...

, partitioning cryptanalysis is a form of cryptanalysis for block ciphers. Developed by Carlo Harpes in 1995, the attack is a generalization of

linear cryptanalysis In cryptography, linear cryptanalysis is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. Attacks have been developed for block ciphers and stream ciphers. Linear cryptanalysis is one of the two mos ...

. Harpes originally replaced the bit sums ( affine transformations) of linear cryptanalysis with more general

balanced In telecommunications and professional audio, a balanced line or balanced signal pair is a circuit consisting of two conductors of the same type, both of which have equal impedances along their lengths and equal impedances to ground and to other ci ...

Boolean function In mathematics, a Boolean function is a function whose arguments and result assume values from a two-element set (usually , or ). Alternative names are switching function, used especially in older computer science literature, and truth function ...

s. He demonstrated a toy cipher that exhibits resistance against ordinary linear cryptanalysis but is susceptible to this sort of partitioning cryptanalysis. In its full generality, partitioning cryptanalysis works by dividing the sets of possible plaintexts and ciphertexts into efficiently-computable

partitions Partition may refer to: Computing Hardware * Disk partitioning, the division of a hard disk drive * Memory partition, a subdivision of a computer's memory, usually for use by a single job Software * Partition (database), the division of a ...

such that the distribution of ciphertexts is significantly non-

uniform A uniform is a variety of clothing worn by members of an organization while participating in that organization's activity. Modern uniforms are most often worn by armed forces and paramilitary organizations such as police, emergency services, ...

when the plaintexts are chosen uniformly from a given block of the partition. Partitioning cryptanalysis has been shown to be more effective than linear cryptanalysis against variants of

DES Des is a masculine given name, mostly a short form (hypocorism) of Desmond. People named Des include: People * Des Buckingham, English football manager * Des Corcoran, (1928–2004), Australian politician * Des Dillon (disambiguation), sever ...

and

CRYPTON In cryptography, CRYPTON is a symmetric block cipher submitted as a candidate for the Advanced Encryption Standard (AES). It is very efficient in hardware implementations and was designed by Chae Hoon Lim of Future Systems Inc. The CRYPTON al ...

. A specific partitioning attack called

mod n cryptanalysis In cryptography, mod ''n'' cryptanalysis is an attack applicable to block and stream ciphers. It is a form of partitioning cryptanalysis that exploits unevenness in how the cipher operates over equivalence classes (congruence classes) modulo '' ...

uses the

congruence class In mathematics, modular arithmetic is a system of arithmetic for integers, where numbers "wrap around" when reaching a certain value, called the modulus. The modern approach to modular arithmetic was developed by Carl Friedrich Gauss in his book ...

es modulo some integer for partitions.

References

* * * * * * * Cryptographic attacks {{crypto-stub