Cryptography - Lecture 19 - Digital Signature Algorithms

This lesson describes digital signature algorithms, which are used to provide authentication of data, and validating the sender. Algorithms discussed include the signature algorithms RSA, ElGamal, & DSA.

Objectives

  • know how digital signature algorithms work in general
  • be able to compute and verify simple example RSA and ElGamal signatures
  • Preliminary Reading

    Stallings, "Cryptography and Network Security", Ch 10.1,10.3,9.4 pp299-303,311-314,293-297

    Lecture Content

    Digital Signature Schemes

    1. Digital Signature Schemes
    2. RSA
    3. RSA Usage
    4. El Gamal Signature Scheme
    5. El Gamal Signature Scheme In Use
    6. Example of ElGamal Signature Scheme
    7. DSA (Digital Signature Algorithm)
    8. DSA Key Generation
    9. DSA Signature Creation and Verification
    10. DSA Security
    11. Fiat-Shamir
    12. Schnorr
    13. Keyed Hash Functions
    14. HMAC

    Summary

    1. Summary

    Exercises

    1. Exercises
      1. Illustrate the operation of El Gamal signatures, given the following parameters:
        • prime p=31
        • prim root a=3
        Determine a suitable private and public key, and then show the signing and verification of a message M=7.
      2. Illustrate the operation of El Gamal encryption, given the following parameters:
        • prime p=31
        • prim root a=12
        Determine a suitable private and public key, and then show the signing and verification of a message M=19.

    Additional References

    For additional information, see:
  • Seberry & Pieprzyk, "Cryptography - An Introduction to Computer Security", 2/e Ch 7.1,7.3,7.4; 1/e Ch 4.3.5 pp165-168.
  • B Schneier, "Applied Cryptography", 2/e, Ch 20.4

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    Lawrie.Brown@adfa.edu.au / 8 Feb 2001