[Page 436] 15.1 Pretty Good Privacy Notation Operational Description Cryptographic Keys and Key Rings Public-Key Management
| 15.2 S/MIME RFC 822 Multipurpose Internet Mail Extensions S/MIME Functionality S/MIME Messages S/MIME Certificate Processing Enhanced Security Services
| 15.3 Key Terms, Review Questions, and Problems Key Terms Review Questions Problems
| Appendix 15A Data Compression Using ZIP Compression Algorithm Decompression Algorithm
| Appendix 15B Radix-64 Conversion | Appendix 15C PGP Random Number Generation True Random Numbers Pseudorandom Numbers
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[Page 437]Despite the refusal of VADM Poindexter and LtCol North to appear, the Board's access to other sources of information filled much of this gap. The FBI provided documents taken from the files of the National Security Advisor and relevant NSC staff members, including messages from the PROF system between VADM Poindexter and LtCol North. The PROF messages were conversations by computer, written at the time events occurred and presumed by the writers to be protected from disclosure. In this sense, they provide a first-hand, contemporaneous account of events. The Tower Commission Report to President Reagan on the Iran-Contra Affair, 1987 Bless the man who made it, And pray that he ain't dead. He could've made a million If he'd sold it to the feds, But he was hot for freedom; He gave it out for free. Now every common citizen's got PGP. From the song "P.G.P."by Leslie Fish Key Points PGP is an open-source freely available software package for e-mail security. It provides authentication through the use of digital signature; confidentiality through the use of symmetric block encryption; compression using the ZIP algorithm; e-mail compatibility using the radix-64 encoding scheme; and segmentation and reassembly to accommodate long e-mails. PGP incorporates tools for developing a public-key trust model and public-key certificate management. S/MIME is an Internet standard approach to e-mail security that incorporates the same functionality as PGP.
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In virtually all distributed environments, electronic mail is the most heavily used network-based application. It is also the only distributed application that is widely used across all architectures and vendor platforms. Users expect to be able to, and do, send mail to others who are connected directly or indirectly to the Internet, regardless of host operating system or communications suite.
[Page 438]With the explosively growing reliance on electronic mail for every conceivable purpose, there grows a demand for authentication and confidentiality services. Two schemes stand out as approaches that enjoy widespread use: Pretty Good Privacy (PGP) and S/MIME. Both are examined in this chapter. | 