IV
https://en.wikipedia.org/wiki/Initialization_vector
In cryptography, an initialization vector (IV) or starting variable (SV) is a fixed-size input to a
cryptographic primitive that is typically required to be random or pseudorandom. Randomization is
crucial for encryption schemes to achieve semantic security, a property whereby repeated usage of
the scheme under the same key does not allow an attacker to infer relationships between segments
of the encrypted message. For block ciphers, the use of an IV is described by the modes of operation.
Randomization is also required for other primitives, such as universal hash functions and message
authentication codes based thereon.
Incorrect answers:
L2TP - PPTP combined with L2F (Layer 2 Forwarding) (Cisco proprietary protocol) - Uses EAP, CHAP,
MS-CHAP, PAP, or S-PAP for authentication. IPSec is used to provide encryption.
Salt - random bits of data intermixed with the message that is to be hashed.
Nonce - an arbitrary number that can be used just once in a cryptographic communication. It is
similar in spirit to a nonce word, hence the name. It is often a random or pseudo-random number
issued in an authentication protocol to ensure that old communications cannot be reused in replay
attacks. They can also be useful as initialization vectors and in cryptographic hash functions.
