Patent ID: 7269261

Claim:
A method for storing and withdrawing a decryption key from a key escrow database, comprising: creating, on a computer, a set of N trap door encryption-decryption function pairs each paired with a corresponding token; transmitting the set of N trap door encryption-decryption function pairs along with a corresponding token to a receiver, the transmission sent over a communication path coupling the receiver and the computer; randomly selecting at the receiver one of the trap door encryption-decryption function pairs and the corresponding token; adding randomization information at the receiver to the corresponding token of the selected trap door encryption-decryption function pair; encrypting the token with the added randomization information at the receiver, the token corresponding with the randomly selected encryption-decryption function pair; recording in a key escrow database the created set of N trap door encryption-decryption function pairs and the corresponding paired token; recording in the key escrow database the randomly selected trap door encryption-decryption function pair along with the encrypted token; and inverting the created set of N trap door encryption-decryption function pairs and the randomly selected trap door encryption-decryption function pair along with the encrypted token to identify the decryption key.