US Patent 7693277 Generating digital signatures using ephemeral cryptographic key

Generating a digital signature utilizing a cryptograph key includes: receiving into a computer system input data from a user (UID); generating within the computer system a cryptographic key as a deterministic function of the UID; clearing from the computer system the UID; generating within the computer system a digital signature as a function of the generated cryptographic key; and clearing the generated cryptographic key from the computer system following generation of the digital signature. The digital signature further may be generated as a function of whether a digital signature has yet been generated using the generated cryptographic key following receipt of the UID. Neither the received UID nor the generated cryptographic key is exported from the computer system.