Explain how can we achieved privacy in an e-mail system. 

The full form of PEM is Privacy Enhanced Mail:

PEM  is  the  internet  Privacy  Enhanced  Mail  standard  adopted  by  Internet Architecture Board (JAB) to private secure electronic mail above the Internet. It was at first designed by the Internet Research Task Force, Privacy and the Security Research Group (PSRG). The   PEM   protocols   provide   for   authentication   message   integrity, the encryption,    and the key management.

PEM Documents are as follows:

The specification for the PEM comes from the following four documents,

™  Messages encryption and the authentication procedures.

™  Certificate-based key management procedure.

™  Algorithms modes and identifiers procedure.

™  Key certification and related services procedure.

Procedure for PEM Messages is given below:

PEM’s core is its message format. The below written format is necessary for PEM the messages.

™  Identifying the type of processing performed on the message that is the PEM messages should be in human readable form.

™  This can be done by using the PEM software. A PEM message is always signed and it is optionally encrypted.

™  Compute the message hash using either the MDI (denoted by “RSA-MD I “) or the MD 5

(Which would be denoted by the “RSA-MD5”)?

™  With the help of DES, encrypt concatenated message (that is hash and message) and encode this message with the base 64 coding and then transmit this message.

™  There are many key certifications  available such as PCA (Policy Certificate Authority), IPRA (Internet Policy Registration Authority). Each certificate has a unique number that includes an MD5 hash signed by the certificate authority’s private key.