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Guessing Entropy

nounid 2692·updated May 12, 2026
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A measure of the difficulty that an Attacker has to guess the average password used in a system. In this document, entropy is stated in bits. When a password has n-bits of guessing entropy then an attacker has as much difficulty guessing the average password as in guessing an n-bit random quantity. The attacker is assumed to know the actual password frequency distribution.

MWE

Classifications

Entity Type

Metric0%rule-basedmulti_axis_classifier_low_confidence.v1

Sensitivity

85%llm-generatedllm:claude-haiku-4-5

Information Class

90%llm-generatedllm:claude-haiku-4-5

Variants

plural
Guessing Entropies
possessive
Guessing Entropy's
pluralpossessive
Guessing Entropies'

Framework definitions

NISTIR 7298: Glossary of Key Information Security Terms, Revision 21 senseview framework →
§1
A measure of the difficulty that an Attacker has to guess the average password used in a system. In this document, entropy is stated in bits. When a password has n-bits of guessing entropy then an attacker has as much difficulty guessing the average password as in guessing an n-bit random quantity. The attacker is assumed to know the actual password frequency distribution.
NIST SP 800-631 senseview framework →
§1
A measure of the difficulty that an Attacker has to guess the average password used in a system. In this document, entropy is stated in bits. When a password has n-bits of guessing entropy then an attacker has as much difficulty guessing the average password as in guessing an n-bit random quantity. The attacker is assumed to know the actual password frequency distribution.

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