We report on experiments on the time of factorization of semiprimes (i.e.,
products of two primes) using the systems ''Sage'' and ''CrypTool''. With some
exceptions the time grows exponentially with the length of the semiprimes - as
expected. Using the quadratic sieve implemented in CrypTool 2, we could
factorize the number RSA-100, a 100-decimal-digits semiprime, on our laptop in
less than eight and a half hours.