Quadratic Sieve Algorithm

The quadratic sieve is an integer factorization algorithm that in practice is the second-fastest method known for factoring large integers, after the general number field sieve, and remains the fastest for integers under about 100 decimal digits while being considerably simpler than the number field sieve. It is a general-purpose factorization algorithm, meaning its running time depends only on the size of the integer being factored rather than on any special structure of that integer, and it was invented by Carl Pomerance in 1981 as an improvement on Schroeppel's earlier linear sieve.