1.4.1 Procedures

Procedure: generate-strong-password KEY: #:length #:include-symbols ¶

Generate a random password designed to be strong.

One character from each included class is guaranteed, the remainder is drawn from the full pool, and the result is shuffled so no positional bias remains.

#:key length: total password length (default 24). Must be at least as large as the number of included character classes. #:key include-symbols: when #t (default) symbols are part of the pool. #:returns: a freshly generated password string.

#:example (generate-strong-password) ; 24 chars, mixed classes (generate-strong-password #:length 32) (generate-strong-password #:length 16 #:include-symbols #f)

Procedure: password-character-classes password ¶

Return the list of character classes present in password.

The returned symbols are drawn from: lowercase, uppercase, digit and symbol. Anything that is not a letter, digit or whitespace is treated as a symbol, so punctuation, math symbols and other printable non-alphanumeric characters are covered.

#:example (password-character-classes "Abc123!") ; => (lowercase uppercase digit symbol)

Procedure: password-entropy KEY: #:password ¶

Return the raw estimated entropy of password in bits.

The estimate is length * log2(pool-size), where the pool size is the sum of the sizes of every character class present in the password. This is a simple model of guessing difficulty, not a guarantee of strength; use ‘password-strength‘ for a penalty-adjusted score.

#:example (password-entropy #:password "Tr0ub4dor&3") ; => a number of bits

Procedure: password-strength KEY: #:password ¶

Measure the strength of password and return an association list describing the result.

The estimate starts from ‘password-entropy‘, then applies penalties for common passwords, short lengths, repeated characters and sequential runs. A common password always scores 0.

The returned alist contains: - score: integer 0 (very weak) to 4 (very strong) - label: human-readable label for the score - entropy: penalty-adjusted entropy estimate, in bits - raw-entropy: unpenalized entropy estimate, in bits - length: length of the password - classes: character classes detected (list of symbols) - feedback: list of suggestions to improve the password

#:example (password-strength #:password "correct horse battery staple")

Procedure: password-strength-label score ¶

Return a human-readable label for a numeric strength score between 0 and 4.

Procedure: strong-password? KEY: #:password #:min-score ¶

Return #t when password scores at least min-score (default 3, "strong") according to ‘password-strength‘, otherwise #f.

#:example (strong-password? #:password "Tr0ub4dor&3") ; => #t or #f (strong-password? #:password "123456" #:min-score 4) ; => #f