You may want to refer to the following sources for background information on network security, cryptography, and SKIP.
Computer Security Policies and SunScreen Firewalls Kathryn M. Walker and Linda Croswhite Cavanaugh Sun Microsystems Press, 1998, ISBN 0-13-096015-0
Access Denied Gene Scott Adams Andrews McMeel, September 1996 ISBN: 0836221915
Building Internet Firewalls, 1st edition D. Brent Chapman and Elizabeth D. Zwicky O'Reilly & Associates, September 1995, ISBN 1-56592-124-0
Firewalls and Internet Security: Repelling the Wily Hacker William R Cheswick and Steven M. Bellovin Addison-Wesley, June 1994, ISBN 0-201-63357-4
Internetworking with TCP/IP, Volume 1: Principles, Protocols, and Architecture Douglas E. Comer Prentice Hall, March 1995, ISBN 0-13-216987-8
Practical UNIX and Internet Security, 2nd edition Simson Garfinkel and Gene Spafford O'Reilly & Associates, April 1996, ISBN 1-56592-148-8
SOLARIS Security, 1st edition Peter H. Gregory Sun Microsystems Press, 2000, ISBN 0-13-096053-5
TCP/IP Network Administration, 2nd edition Craig Hunt O'Reilly & Associates, December 1997, ISBN 1-56592-322-7
Network Security: Private Communication in a Public World Charlie Kaufman, Radia Perlman, and Mike Speciner Prentice Hall, March 1995, ISBN 0-13-061466-1
Applied Cryptography, 2nd edition Bruce Schneier John Wiley & Sons, 1996, ISBN 0-471-12845-7
Network Security Essentials: Applications and Standards William Stallings Prentice Hall, November 1999, ISBN 0-13-016093-8
Cryptography and Network Security: Principles and Practice William Stallings Prentice Hall, June 1998, ISBN 0-13-869017-0
TCP/IP Illustrated, Volume 1 The Protocols W. Richard Stevens Addison-Wesley, January 1994, ISBN 0-201-63346-9
TCP/IP Illustrated, Volume 3: TCP for Transactions, HTTP, NNTP, and the UNIX Domain Protocols W. Richard Stevens Addison-Wesley, January 1996, ISBN 0-201-63495-3
UNIX Network Programming, Volume 1: Networking APIs: Sockets and XTI W. Richard Stevens Prentice Hall, January 1994, ISBN 0-201-63346-9
UNIX Network Programming, Volume 2: Interprocess Communications W. Richard Stevens Prentice Hall, August 1998, ISBN 0-103-81081-9
Firewalls 24seven, 1st edition Matthew Strebe and Charles Perkins Sybex, Inc., 1999, ISBN 0-782-12529-8
SKIP IP-Level Cryptography [http://skip.incog.com/]
Sun Software and Networking Security [http://www.sun.com/security/]