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Fermat's factorization method, named after Pierre de Fermat, is based on the representation of an odd integer as the difference of two squares: N = a 2 − b 2 . {\displaystyle N=a^{2}-b^{2}.} That difference is algebraically factorable as ( a + b ) ( a − b ) {\displaystyle (a+b)(a-b)} ; if neither factor equals one, it is a proper ...
To factorize the integer n, Fermat's method entails a search for a single number a, n 1/2 < a < n−1, such that the remainder of a 2 divided by n is a square. But these a are hard to find. The quadratic sieve consists of computing the remainder of a 2 /n for several a, then finding a subset of these whose product is a square. This will yield a ...
Dixon's factorization method; E. Euler's factorization method; F. Factor base; Fast Library for Number Theory; Fermat's factorization method; G. General number field ...
Shanks' square forms factorization is a method for integer factorization devised by Daniel Shanks as an improvement on Fermat's factorization method. The success of Fermat's method depends on finding integers x {\displaystyle x} and y {\displaystyle y} such that x 2 − y 2 = N {\displaystyle x^{2}-y^{2}=N} , where N {\displaystyle N} is the ...
-in order for a² - N to be square. As you can notice, all even N are skipped - Fermat method does not test them.. Example in hexadecimal format: Let N be 1751 16. The right digit of N is 1, from table, right digit of a can only be 1,7,9 or F. √1751 16 = 4E, so we test for a only 4F, 51, 57 and get result a² - N = 57 16 2 - 1751 16 as a perfect square.
Dixon's method is based on finding a congruence of squares modulo the integer N which is intended to factor. Fermat's factorization method finds such a congruence by selecting random or pseudo-random x values and hoping that the integer x 2 mod N is a perfect square (in the integers):
Some of the proofs of Fermat's little theorem given below depend on two simplifications. The first is that we may assume that a is in the range 0 ≤ a ≤ p − 1 . This is a simple consequence of the laws of modular arithmetic ; we are simply saying that we may first reduce a modulo p .
The SNFS works as follows. Let n be the integer we want to factor. As in the rational sieve, the SNFS can be broken into two steps: First, find a large number of multiplicative relations among a factor base of elements of Z/nZ, such that the number of multiplicative relations is larger than the number of elements in the factor base.