acceptable_password(3)acceptable_password(3)NAMEacceptable_password - Determines if a password meets deduction require‐
ments (Enhanced Security)
FILE *stream );
Enhanced Security Library (libsecurity)
Points to the suggested password. Points to the stream to write diag‐
The acceptable_password() function determines if the given password is
difficult to deduce from well known, password-guessing heuristics. The
cleartext (plaintext) password is passed as the first argument, and the
file pointer of the stream that is used to report failure reasons is
the second argument. If this checking is to be silent, the second
argument should be a null file pointer.
When the acceptable_password() function returns a value of 1, the pass‐
word provided meets all the tests listed in the following text. When it
returns a value of 0 (zero), the password failed to meet at least one
of the tests.
The selectivity criteria for the password include but cannot be limited
to the following four tests: This test passes if the word is not a
palindrome. (A palindrome is a word that is spelled the same backwards
as it is forwards.) Examples of palindromes that fail this test are
mom, dad, noon, redivider, radar. Palindromes do not make good pass‐
words because they reduce an n character password to n/2 + 1 charac‐
ters. A penetrator knowing that palindromes were legal could use
heuristics that could deduce the password much more quickly than if
they were excluded. This test passes if the password is not a deriva‐
tive of a login name for the system. Many insecure systems allow pass‐
words to be the login name itself. This is a fact known by many pene‐
trators. All login names are excluded because a user that is the owner
of several pseudouser accounts can elect to use the login name of one
account as the password for all accounts. Similar to the login name
issue, this test passes if the password is not a group name derivative.
This test passes if the spell program determines that the password is
not an English word. A penetrator then could not search the online
dictionary to find the password. The spell program also has some
built-in rules that go beyond the actual online dictionary in determin‐
ing what is a proper word, and this routine takes advantage of that.
Programs that use this routine must be compiled with -lsecurity.
System password file. System group file.
Functions: getpwent(3), getgrent(3)acceptable_password(3)