The sender uses PGP to create a digital signature for the message with either the RSA or DSA algorithms. Because the content is encrypted, any changes in the message will fail the decryption with the appropriate key. The latter is used to detect whether a message has been altered since it was completed (the message integrity property) and the former, to determine whether it was actually sent by the person or entity claimed to be the sender (a digital signature). PGP supports message authentication and integrity checking. Only the private key belonging to the receiver can decrypt the session key, and use it to symmetrically decrypt the message. The session key must be sent to the receiver so they know how to decrypt the message, but to protect it during transmission it is encrypted with the receiver's public key. The message and its session key are sent to the receiver. The symmetric key is used only once and is also called a session key.

The message is encrypted using symmetric encryption algorithm, which requires a symmetric key generated by the sender. For this, PGP uses a hybrid cryptosystem by combining symmetric-key encryption and public-key encryption.

PGP can be used to send messages confidentially. Therefore, it is essential that partners in PGP communication understand each other's capabilities or at least agree on PGP settings. Compatibility Īs PGP evolves, versions that support newer features and algorithms can create encrypted messages that older PGP systems cannot decrypt, even with a valid private key. A fingerprint like C3A6 5E46 7B54 77DF 3C4C 9790 4D22 B3CA 5B32 FF66 can be printed on a business card. From a fingerprint, someone can validate the correct corresponding public key. Current versions of PGP encryption include options through an automated key management server.Ī public key fingerprint is a shorter version of a public key. The first version of this system was generally known as a web of trust to contrast with the X.509 system, which uses a hierarchical approach based on certificate authority and which was added to PGP implementations later. Each public key is bound to a username or an e-mail address. PGP encryption uses a serial combination of hashing, data compression, symmetric-key cryptography, and finally public-key cryptography each step uses one of several supported algorithms.

5 x 7 envelopes target