Describe some of the common protocols used to secure e-mail.

Question

What will be an ideal response?

Answer 1

Mail Extensions (MIME) that encode format by adding encryption and authentication via digital signatures based on public key cryptosystems. Privacy Enhanced Mail (PEM) has been proposed by the Internet Engineering Task Force (IETF) as a standard for public key cryptosystems. PEM uses 3DES symmetric key encryption and RSA for key exchanges and digital signatures. Pretty Good Privacy (PGP) was developed by Phil Zimmerman and uses the IDEA Cipher, a 128-bit symmetric key block encryption algorithm with 64-bit blocks for message encoding. Like PEM, it uses RSA for symmetric key exchange  and to support digital signatures. PGP does not use a centralized certificate authority; rather, it relies on a "web of trust" model to allow its users to share key information easily, albeit with some loss in the degree of control and trust in the key information. If user A has a trusting relationship with user B, and user B has a trusting relationship with user C, then user A is presumed to have a trusting relationship with user C and can therefore exchange encrypted information with user C.