PrettyGoodPrivacy

PGP (PrettyGoodPrivacy) is an application developed by PhilZimmermann that provides an easy to use interface for high security encryption of emails and other sensitive content. The newer PGP packages contain plug-ins for most modern email applications like MicrosoftOutlook, OutlookExpress and NetscapeMessenger. PGP uses AsymmetricEncryption with a PublicKey and a PrivateKey which are used to sign and encrypt a message. The PublicKey is publicly available on some of the many KeyServer around the world and it can be used to encrypt a message to the owner of the PublicKey or to verify a signature of the keyowner. The recipient of the encrypted message can then decrypt this message using his PrivateKey. To verify whether an email was not altered during transmission and whether it was really sent by the specified sender you can use PGP to electronically sign your mail. PGP then creats a HashCode of the message, which is then encrypted using the PrivateKey of the signer. The recipient of the mail uses the PublicKey of the signer to decrypt the HashCode which is then compared to the HashCode the recipient computes using the mail content. Only if both hashes are the same the mail was not altered. Currently there exists an open source and free replacement for PGP called GnuPG.