International Business Machines Corporation

Coimbatore S Chandersekaran

Nevenko Zunic

David R Safford

Rosario Gennaro

Sarbari Gupta

Stephen M Matyas

Stephen Michael Matyas, Jr

A method and apparatus for ensuring that a key recovery-enabled (KR-enabled) system communicating with a non-KR-enabled system in a cryptographic communication system transmits the information necessary to permit key recovery by a key recovery entity. In a first embodiment, data is encrypted under a second key K that is generated as a one-way function of a first key K&prime; and a key recovery block KRB generated on the first key K&prime;. The key recovery block KRB and the encrypted data e(K, data) are transmitted to the receiver, who cannot decrypt the data without regenerating the second key K from the first key K&prime; and the key recovery block KRB. In a second embodiment, data is encrypted under a second key K that is generated independently of the first key K&prime;. A third key X, generated as a one-way function of the first key K&prime; and a key recovery block KRB generated on the second key K, is used to encrypt the XOR product Y of the first and second keys K&prime;, K. The key recovery block KRB, the encrypted XOR product e(X, Y) and the encrypted data e(K, data) are transmitted to the receiver, who cannot decrypt the data without regenerating the third key X from the first key K&prime; and the key recovery block KRB, decrypting the XOR product Y using the regenerated third key X, and recombining the XOR product Y with the first key K&Prime; to regenerate the second key K. In a third embodiment, an integrity value is computed on a key K and its key recovery block KRB. The integrity value and the key K are encrypted to form an encrypted portion of a key exchange block KEB, while the key recovery block KRB is put in an unencrypted portion of the key exchange block KEB, which is sent along with the encrypted data e(K, data) to the receiver. The receiver decrypts the encrypted portion, recomputes the integrity value and compares it with the received integrity value. Only if the two integrity values compare is the key K extracted and used to decrypt the data.

Method and apparatus for providing interoperability between key recovery and non-key recovery systems

In a cryptographic communications system, a method and apparatus for allowing a sender of encrypted data to demonstrate to a receiver its ability to correctly generate key recovery information that is transmitted along with the encrypted data and from which law enforcement agents or others may recover the original encryption key. Initially, the sender generates a key pair comprising a private signature key and a corresponding public verification key and sends the latter to a key recovery validation service (KRVS). Upon a satisfactory demonstration by the sender of its ability to correctly generate key recovery information, the KRVS generates a certificate certifying the public verification key and the ability of the sender to correctly generate key recovery information. The sender uses its private signature key to generate a digital signature on the key recovery information, which is sent along with the key recovery information and encrypted data to the receiver. The receiver verifies the signature on the key recovery information using the certified public verification key and decrypts the encrypted data only if the signature is verified as being a valid signature.

Method and apparatus for interoperable validation of key recovery

Growing community of inventors

Potomac, MD, United States of America

Coimbatore S Chandersekaran