What function does a conventional encryption algorithm perform in PGP?
Block ciphers are used in numerous areas of PGP: • Bulk encryption of data. Session keys are encrypted with the public key algorithm, and then the bulk of data is encrypted with a conventional block cipher. This is done for reasons of security and speed. • Maintaining the pool of random data. • Encrypting the keys stored in the private keyring. This keyring holds the private decryption key(s) and it is imperative that this file is encrypted in a “secure” manner. It is interesting to note that the whole of private keyring is not encrypted – but only the actual private key data. Thus someone obtaining a private keyring would obtain details of all ‘nym userids and public parameters [Bac99a].
