References

• 'Introduction to Algorithms' by Thomas H. Cormen, Charles E. Leiserson and Ronald L. Riverest

  Excelent on the maths and proofs behind public-private key cryptography and the algorthims involved in working with [large] prime numbers.

• 'Codes and Cryptography' by Dominic Welsh.

  More algorithms and proofs.

• 'PGP: Pretty Good Privacy' by Simson Garfinkel - O'Reilly and Associates, Inc

• RFC1321

  Describes the MD5 algorithm.

• 'GnuPG'

  A free software implementation of PGP.