Nonce

nounid 3384·updated May 18, 2026
candidate

A value used in security protocols that is never repeated with the same key. For example, nonces used as challenges in challenge-response authentication protocols generally must not be repeated until authentication keys are changed. Otherwise, there is a possibility of a replay attack. Using a nonce as a challenge is a different requirement than a random challenge, because a nonce is not necessarily unpredictable.

Attested in

No recorded attestations. They are written when an MWE tagging stage is completed, stamped with the pack version and the document’s digest.

Classifications

Entity Type

Credential0%rule-basedmulti_axis_classifier_low_confidence.v1

Sensitivity

60%llm-generatedllm:claude-haiku-4-5

Information Class

70%llm-generatedllm:claude-haiku-4-5

Variants

synonym
time being
plural
Nonces
possessive
Nonce's
pluralpossessive
Nonces'

Framework definitions

NISTIR 7298: Glossary of Key Information Security Terms, Revision 22 sensesview framework →
§1
A value used in security protocols that is never repeated with the same key. For example, nonces used as challenges in challenge-response authentication protocols generally must not be repeated until authentication keys are changed. Otherwise, there is a possibility of a replay attack. Using a nonce as a challenge is a different requirement than a random challenge, because a nonce is not necessarily unpredictable.
§2 · sense_2_pending_review
A random or non-repeating value that is included in data exchanged by a protocol, usually for the purpose of guaranteeing the transmittal of live data rather than replayed data, thus detecting and protecting against replay attacks.
CNSSI-4009 (Glossary of Information Assurance Terms)1 senseview framework →
§1
A random or non-repeating value that is included in data exchanged by a protocol, usually for the purpose of guaranteeing the transmittal of live data rather than replayed data, thus detecting and protecting against replay attacks.
NIST SP 800-631 senseview framework →
§1
A value used in security protocols that is never repeated with the same key. For example, nonces used as challenges in challenge-response authentication protocols generally must not be repeated until authentication keys are changed. Otherwise, there is a possibility of a replay attack. Using a nonce as a challenge is a different requirement than a random challenge, because a nonce is not necessarily unpredictable.
Wordset Dictionary1 senseview framework →
§1
the present occasion
Legacy lexicon import1 senseview framework →
§1 · legacy_primary
A value used in security protocols that is never repeated with the same key. For example, nonces used as challenges in challenge-response authentication protocols generally must not be repeated until authentication keys are changed. Otherwise, there is a possibility of a replay attack. Using a nonce as a challenge is a different requirement than a random challenge, because a nonce is not necessarily unpredictable.
DR-088 backfill from the noun definition column

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