SSH vs. PGP vs. SSL Keys
• SSH, PGP, and SSL key pairs are all based on the Public-Key Cryptography Infrastructure (PKI) and its asymmetric cryptography structure - the public-private key pair.
• The only difference between them is their purpose:
◇ SSH key pairs – encrypt and authenticate remote connections
◇ PGP key pairs – encrypt e-mails, disks, arbitrary files to securely sign or delete them.
◇ SSL key pairs – encrypt TCP/IP communications and secure browser-server connections (used for SSL Certificates).
• For more details on SSH, PGP, and SSL, check my answers to “What is the difference between SSL and SSH?” and “Can the term PKI be used to express a public key infrastructure without the use of Certification Authorities?”.
GPG vs. PGP
• GnuPG is an free and open-source implementation of the OpenPGP standard.
• Symantec PGP is a proprietary implementation of the OpenPGP standard.