Two major schemes for Email Security: PGP and S/MIME
1.PGP: A package of five services
a.Authentication — Digital Signature by HASH + RSA
b.Confidentiality
i.Generate a one-time symmertric key for each msg
ii.Distribute this key by encrypting it with receiver’s public key
c.Compression
d.Email Compatibility
e.Sementation
2.S/MIMIE: Let’s review it later