Summation generator
Encyclopedia
The summation generator, created in 1985, by Rainer Rueppel, was a cryptography
and security front-runner in the late 1980s. It operates by taking the output of two LFSR's through an adder with carry. The operation's strength is that it is nonlinear. However, through the early 1990s various attacks against the summation generator eventually led to its fall to a correlation
attack. In 1995 Klapper and Goresky were able to determine the summation generator's sequence in only 219 bits.
An improved summation generator with 2-bit memory was then proposed by cryptographers Lee and Moon. In the new generator scheme an extra bit
of memory is added to the nonlinear combining function
. The objective in the modification was to make the summation generator immune to correlation attack
.
An attack against the improved summation generator was reported by Mex-Perera and Shepherd in 2002 by exploting linear relations. Besides, in June 2005 an algebraic
attack was developed. Using this attack a PC can calculate the initial state of the summation generator within 3 minutes even with 256 bit LFSR's
Cryptography
Cryptography is the practice and study of techniques for secure communication in the presence of third parties...
and security front-runner in the late 1980s. It operates by taking the output of two LFSR's through an adder with carry. The operation's strength is that it is nonlinear. However, through the early 1990s various attacks against the summation generator eventually led to its fall to a correlation
Correlation
In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....
attack. In 1995 Klapper and Goresky were able to determine the summation generator's sequence in only 219 bits.
An improved summation generator with 2-bit memory was then proposed by cryptographers Lee and Moon. In the new generator scheme an extra bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
of memory is added to the nonlinear combining function
Function (mathematics)
In mathematics, a function associates one quantity, the argument of the function, also known as the input, with another quantity, the value of the function, also known as the output. A function assigns exactly one output to each input. The argument and the value may be real numbers, but they can...
. The objective in the modification was to make the summation generator immune to correlation attack
Correlation attack
In cryptography, correlation attacks are a class of known plaintext attacks for breaking stream ciphers whose keystream is generated by combining the output of several linear feedback shift registers using a Boolean function...
.
An attack against the improved summation generator was reported by Mex-Perera and Shepherd in 2002 by exploting linear relations. Besides, in June 2005 an algebraic
Algebraic
Algebraic may refer to any subject within the algebra branch of mathematics and related branches like algebraic geometry and algebraic topology.Algebraic may also refer to:...
attack was developed. Using this attack a PC can calculate the initial state of the summation generator within 3 minutes even with 256 bit LFSR's