A collision attack exists that can find collisions within seconds on a computer with a 2.6 GHz Pentium 4 processor (complexity of 2^24.1). Further, there is also a chosen-prefix collision attack that can produce a collision for two chosen arbitrarily different inputs within hours, using off-the-shelf computing hardware (complexity 2^39). The ability to find collisions has been greatly aided by the use of off-the-shelf GPUs. On an NVIDIA GeForce 8400GS graphics processor, 16–18 million hashes per second can be computed. An NVIDIA GeForce 8800 Ultra can calculate more than 200 million hashes per second.