A Randomized Protocol for Signing Contracts

  • S. Even
  • O. Goldreich
  • A. Lempel


Suppose two parties A, and B, in a communication network, have negotiated a contract, which they wish to sign. To this end, they need a protocol which has the two following properties:
  1. (1)

    At the end of an honest execution of the protocol, each party has a signature of the other.

  2. (2)

    If one party, X, executes the protocol honestly, his counterpoint, Y, cannot obtain X’s signature to the contract without yielding his own signature.



Conventional System Data Encryption Decryption Algorithm Threshold Scheme Oblivious Transfer 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Even, S., and Yacobi, Y., Relations Among Public Key Signature Systems, TR#175, Computer Science Dept., Technion, Haifa, Israel, March 1980.Google Scholar
  2. [2]
    Even, S., A Protocol for Signing Contracts, TR#231, Computer Science Dept., Technion, Haifa, Israel, January 1982.Google Scholar
  3. [3]
    Merkle, R.C., Secure Communication Over Insecure Channel, Comm. ACM, Vol. 21, April 1978, pp. 294–299.CrossRefGoogle Scholar
  4. [4]
    Blum, M., and Rabin, M.O., How to Send Certified Electronic Mail. In preparation.Google Scholar
  5. [5]
    Blum, M., How to Exchange (secret) Keys, Memo No. UCB/ERL M81/90, March 1982. To appear in CACM.Google Scholar
  6. [6]
    Rabin, M.O., Private communication.Google Scholar
  7. [7]
    Diffie, W., and Hellman, M.E., New Directions in Cryptography, IEEE Trans. Inform. Theory, Vol. IT-22, No. 6, November 1976, pp. 644–654.CrossRefGoogle Scholar
  8. [8]
    Data Encryption Standard, National Bureau of Standards, Federal Information Processing Standards, Publ. 46, 1977.Google Scholar
  9. [9]
    Rivest, R., Shamir, A., and Adleman, L., A Method for Obtain- ing Digital Signatures and Public Key Cryptosystems. Comm. ACM, Vol 21, February 1978, pp. 120–126.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1983

Authors and Affiliations

  • S. Even
    • 1
  • O. Goldreich
    • 1
  • A. Lempel
    • 1
  1. 1.Computer Science DepartmentTechnion — Israel Institute of TechnologyHaifaIsrael

Personalised recommendations