Patents by Inventor Nevenko Zunic

Nevenko Zunic has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6052469
    Abstract: 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.
    Type: Grant
    Filed: August 14, 1998
    Date of Patent: April 18, 2000
    Assignee: International Business Machines Corporation
    Inventors: Donald Byron Johnson, Paul Ashley Karger, Charles William Kaufman, Jr., Stephen Michael Matyas, Jr., David Robert Safford, Marcel Mordechay Yung, Nevenko Zunic
  • Patent number: 5937066
    Abstract: A cryptographic key recovery system that operates in two phases. In the first phase, the sender establishes a secret value with the receiver. For each key recovery agent, the sender generates a key-generating value as a one-way function of the secret value and encrypts the key-generating value with a public key of the key recovery agent. In the second phase, performed for a particular cryptographic session, the sender generates for each key recovery agent a key-encrypting key as a one-way function of the corresponding key-generating value and multiply encrypts the session key with the key-encrypting keys of the key recovery agents. The encrypted key-generating values and the multiply encrypted session key are transmitted together with other recovery information in a manner permitting their interception by a party seeking to recover the secret value.
    Type: Grant
    Filed: October 2, 1996
    Date of Patent: August 10, 1999
    Assignee: International Business Machines Corporation
    Inventors: Rosario Gennaro, Donald Byron Johnson, Paul Ashley Karger, Stephen Michael Matyas, Jr., Mohammad Peyravian, David Robert Safford, Marcel Mordechay Yung, Nevenko Zunic
  • Patent number: 5907618
    Abstract: A method and apparatus for verifiably providing key recovery information to one or more trustees in a cryptographic communication system having a sender and a receiver Each communicating party has its own Diffie-Hellman key pair comprising a secret value and corresponding public value, as does each trustee The sender non-interactively generates from its own secret value and the public value held by the receiver a first shared Diffie-Hellman key pair comprising a first shared secret value, shared with the receiver but not with any trustee, and a corresponding public value. For each trustee, the sender then non-interactively generates an additional shared secret value, shared with the receiver and the trustee, from the first shared secret value and the public value corresponding to the secret value held by the trustee. The sender uses the additional shared secret value to encrypt recovery information for each trustee, which is transmitted to the receiver along with the encrypted message.
    Type: Grant
    Filed: January 3, 1997
    Date of Patent: May 25, 1999
    Assignee: International Business Machines Corporation
    Inventors: Rosario Gennaro, Paul Ashley Karger, Stephen Michael Matyas, Jr., Mohammad Peyravian, David Robert Safford, Nevenko Zunic
  • Patent number: 5815573
    Abstract: A cryptographic key recovery system for generating a cryptographic key for use by a pair of communicating parties while simultaneously providing for its recovery using one or more key recover agents. A plurality of m-bit shared key parts (P, Q) are generated which are shared with respective key recovery agents, while an n-bit nonshared key part (R) is generated that is not shared with any key recovery agent. The shared key parts (P, Q) are combined to generate an m-bit value which is concatenated with the nonshared key part (R) to generate an (m+n)-bit value from which an encryption key is generated. The cryptographic system has the effective work factor of an n-bit key to all of the key recovery agents acting in concert, but has the effective work factor of an (m+n)-bit to any other combination of third parties.
    Type: Grant
    Filed: April 10, 1996
    Date of Patent: September 29, 1998
    Assignee: International Business Machines Corporation
    Inventors: Donald Byron Johnson, Paul Ashley Karger, Charles William Kaufman, Jr., Stephen Michael Matyas, Jr., Marcel Mordechay Yung, Nevenko Zunic
  • Patent number: 5796830
    Abstract: 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.
    Type: Grant
    Filed: July 29, 1996
    Date of Patent: August 18, 1998
    Assignee: International Business Machines Corporation
    Inventors: Donald Byron Johnson, Paul Ashley Karger, Charles William Kaufman, Jr., Stephen Michael Matyas, Jr., David Robert Safford, Marcel Mordechay Yung, Nevenko Zunic