Initialization Vector (IV) - Glossary (2024)

Definitions:

A binary vector used as the input to initialize the algorithm for the encryption of a plaintext block sequence to increase security by introducing additional cryptographic variance and to synchronize cryptographic equipment. The initialization vector need not be secret. Some of the Triple Data Encryption Algorithm Modes of Operation require 3 initialization vectors.
Sources:
NIST SP 800-20 under Initialization Vector

Initialization Vector
Sources:
NIST SP 800-20 under IV
NIST SP 800-38D under IV

A data block that some modes of operation require as an additional initial input.
Sources:
NIST SP 800-38A

The initialization vector.
Sources:
NIST SP 800-38A under IV
NIST SP 800-38D under IV

A nonce that is associated with an invocation of authenticated encryption on a particular plaintext and AAD.
Sources:
NIST SP 800-38D under Initialization Vector

A vector used in defining the starting point of a cryptographic process.
Sources:
NIST SP 800-175B Rev. 1
NIST SP 800-57 Part 1 Rev. 5 under Initialization vector (IV)

A vector used in defining the starting point of a cryptographic process (e.g., encryption and key wrapping).
Sources:
NIST SP 800-57 Part 2 Rev.1

A bit string that is used as an initial value in computing the first iteration of the PRF in feedback mode. It may be an empty string.
Sources:
NIST SP 800-108r1 [August 2022 (Includes updates as of 02-02-2024)] under IV

Glossary Comments

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Comments about the glossary's presentation and functionality should be sent to secglossary@nist.gov.

See NISTIR 7298 Rev. 3 for additional details.