Whitfield Diffie and Martin E. Hellman: "New Directions in Cryptography." IEEE Transactions on Information Theory, v. IT-22, n. 6, November 1976, pp. 644-654.
[Krawczyk]
Hugo Krawczyk: "SKEME: A Versatile Secure Key Exchange Mechanism for Internet." IBM, Hawthorne, NY, 1995.
[MD5]
R.L. Rivest, "The MD5 Message Digest Algorithm," RFC1321, 1992.
[PKCS1]
PKCS #1: RSA Encryption Standard. RSA Laboratories, Redwood City, CA, 1993.
[PKCS7]
PKCS #7: Cryptographic Message Syntax Standard. RSA Laboratories, Redwood City, CA, 1993.
[RSA FAQ]
Frequently Asked Questions: Cryptography--The Latest from RSA Labs. RSA Laboratories, Redwood City, CA, 1996.
[Schneier]
Schneier, Bruce: Applied Cryptography. John Wiley & Sons, 1996.