 Keys of 512 bits have been shown to be practically breakable in 1999 when RSA-155 was factored by using several hundred computers, and these are now factored in a few weeks using common hardware.Exploits using 512-bit code-signing certificates that may have been factored were reported in 2011.A theoretical hardware device named TWIRL, described by Shamir and Tromer in 2003, called into question the security of 1024 bit keys.