What is Shared secret?
In [[cryptography]], a '''shared secret''' is a piece of data only known to the parties involved in a secure communication. The shared secret can be a [[password]], a [[passphrase]], a big number or an array of randomly chosen bytes. The shared secret is either shared before parties start to communicate; in this case it can also be called a [[pre-shared key]]. Or it is created at the start of the communication session by using a [[key-agreement protocol]], for-instance using [[public-key cryptography]] such as [[Diffie-Hellman key exchange|Diffie-Hellman]] or using [[symmetric-key algorithm|symmetric-key cryptography]] such as [[Kerberos (protocol)|Kerberos]]. The shared secret can be used for authentication (for instance when logging in to a remote system) using methods such as [[Challenge-response authentication|challenge-response]] or it can be fed to a [[key derivation function]] to produce one or more [[key (cryptography)|keys]] to use for [[encryption]] and/or [[Message authentication code|MACing]] of messages. To make unique [[Session key|session and message keys]] the shared secret is usually combined with an [[initialization vector]] (IV). An example of this is the [[derived unique key per transaction]] method. == References == <references/> * ''[http://www.cacr.math.uwaterloo.ca/hac/ Handbook of Applied Cryptography]'' by Menezes, van Oorschot and Vanstone (2001), chapter 10 and 12. {{Cryptography navbox}} {{math-stub}} [[Category:Cryptography]]