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In cryptography, a pre-shared key or PSK is a shared secret which was previously shared between the two parties using some secure channel before it is used. Such systems almost always use symmetric key cryptographic algorithms.
Shared Key Encryption For shared key cryptography to work, the sender and the recipient of a message must both have the same key, which they must keep secret from everybody else. The sender uses the shared key to encrypt a message, shown in the following figure, and then sends the ciphertext message to the recipient.
Which is better shared secret or public key?
For that, symmetric cryptography is much better, with “secret keys” (i.e. keys which do not have a public face, they are 100% secret). Diffie-Hellman is an asymmetric key exchange algorithm, in which two parties do the mathematics of DH and end up with a shared secret, i.e. a key: they both know it (thus “shared”), but nobody else (thus “secret”).
How is a shared secret used in cryptography?
Very often, the shared secret value is itself used as a key in some second cryptographic protocol which is based on symmetric cryptography (i.e. with a shared key), for example one based on AES.
How are public and private keys used in asymmetric encryption?
Asymmetric encryption is also called public key encryption, but it actually relies on a key pair. Two mathematically related keys, one called the public key and another called the private key, are generated to be used together. The private key is never shared; it is kept secret and is used only by its owner.
One of the more common issues identified during Wireless Network assessments is that organisations often utilise Pre-Shared-Keys (PSKs) for authentication, despite usually having relatively strong configurations for encryption.