초록 ▼

A cryptographic key recovery system that is interoperable with existing systems for establishing keys between communicating parties. The sender uses a reversible key inversion function to generate key recovery values P, Q and (optionally) R as a function of a session key and public information, so t

A cryptographic key recovery system that is interoperable with existing systems for establishing keys between communicating parties. The sender uses a reversible key inversion function to generate key recovery values P, Q and (optionally) R as a function of a session key and public information, so that the session key may be regenerated from the key recovery values P, Q and (if generated) R. Key recovery values P and Q are encrypted using the respective public recovery keys of a pair of key recovery agents. The encrypted P and Q values are included along with other recovery information in a session header accompanying an encrypted message sent from the sender to the receiver. The key recovery agents may recover the P and Q values for a law enforcement agent by decrypting the encrypted P and Q values in the session header, using their respective private recovery keys corresponding to the public keys. The R value, if generated, is not made available to the key recovery agents, but is ascertained using standard cryptanalytic techniques in order to provide a nontrivial work factor for law enforcement agents. The receiver checks the session header of a received message to ensure that the sender has included valid recovery information. Only when the receiver has verified that the sender has included valid recovery information does the receiver decrypt the received message.

대표청구항 ▼

[ What is claimed is:] [1.] A method of providing, in a manner verifiable by a possessor of a cryptographic key, for the recovery of said key using a plurality of cooperating key recovery agents, comprising the steps of:receiving a plurality of shared key recovery values from which said key may be r

[ What is claimed is:] [1.] A method of providing, in a manner verifiable by a possessor of a cryptographic key, for the recovery of said key using a plurality of cooperating key recovery agents, comprising the steps of:receiving a plurality of shared key recovery values from which said key may be recovered, said key being recoverable from said plurality of shared key recovery values collectively by combining them to recover said key but not being recoverable from any single shared key recovery value individually, said key recovery values being generated as a function only of said key and public information and being encrypted under respective keys of said key recovery agents to generate encrypted recovery values;generating said shared key recovery values from said cryptographic key and said public information;encrypting said generated shared key recovery values under said encryption keys of said key recovery agents to generate comparison encrypted recovery values; andcomparing said received encrypted recovery values with said comparison encrypted recovery values to verify said received encrypted recovery values.