The topic of digital signing is discussed more fully in the following documents:
CCITT, Recommendation X.509, The Directory-Authentication Framework, Consultation Committee, International Telephone and Telegraph, International Telecommunications Union, Geneva, 1989.
Microsoft Cryptographic Service Provider Programmer's Guide, Microsoft, 1995.
Microsoft Application Programmer's Guide, Microsoft, 1995
RSA Laboratories, PKCS#7: Cryptographic Message Syntax Standard. Version 1.5, November, 1993.
Schneier, Bruce. Applied Cryptography, 2d ed. New York: John Wiley & Sons, 1996.
http://www.microsoft.com/devonly/
http://rsa.com