HP StorageWorks 1606 Brocade Web Tools Administrator's Guide v6.3.0 (53-100134 - Page 293

IPSec Concepts 17 Authentication methods The methods used to authenticate the IKE peer are preshared key (psk), DSS digital signature (dss), and RSA digital signature (rsasig): • A Preshared key (PSK) is a shared secret that is shared between two parties over a secure channel before it is used. Typically, the PSK is a password or pass phrase. PSKs are created in the end systems used by the two parties. There are several tools available to help choose a strong key that will work with various operating systems. When choosing a tool and creating a PSK, keep in mind that the cryptographic strength of a key generally increases with length. • The Digital Signature Standard (DSS) makes use of a private key to generate a digital signature. Each user possesses a private and public key pair. Signature generation can be performed only by the possessor of the user's private key. The digital signature is sent to the intended verifier in a message. The verifier of the message and signature verifies the signature by using the sender's public key. • The RSA digital signature process uses a private key to encrypt only the message digest. The encrypted message digest becomes the digital signature and is attached to the original data. To verify the contents of digitally signed data, the recipient generates a new message digest from the data that was received, decrypts the original message digest with the originator's public key, and compares the decrypted digest with the newly generated digest. If the two digests match, the integrity of the message is verified. The identity of the originator also is confirmed because the public key can decrypt only data that has been encrypted with the corresponding private key. Web Tools Administrator's Guide 261 53-1001343-01