Cryptography

* S/MIME
* PGP

S/MIME - Secure Multipurpose Internet Mail Extensions uses digital certificates to sign and/or encrypt e-mail (Note: Thawte's digital certificates for personal use are free). S/MIME specification mandates support for 3DES as an encryption algorithm, DH for key encryption and DSS as a signature algorithm.

Digital Signature - first generate a hash for the entire message and then encrypt the hash with the sender's private key. Both DSS (Digital Signature Standard) and RSA can be used to generate digital signatures.

PGP is a hybrid cryptosystem. If first compresses the plaintext, then creates a session key. This one-time-only secret key encrypts the data. When the data is encrypted, the session key is then encrypted with the recipient's public key. This public key-encrypted session key is transmitted along with the ciphertext to the recipient. PGP also uses DSS as signature algorithm.

# posted by - H - @ 10:40 PM