NAME

       crypt_checksalt — validate a crypt setting string

LIBRARY

       Crypt Library (libcrypt, -lcrypt)

SYNOPSIS

       #include <crypt.h>

       int
       crypt_checksalt(const char *setting);

DESCRIPTION

       crypt_checksalt  checks  the  setting  string  against  the  system configuration and reports whether the
       hashing method and parameters it specifies are acceptable.  It is intended to be used by programs such as
       login(1) to determine whether the user's passphrase should be re-hashed  using  the  currently  preferred
       hashing method.

RETURN VALUES

       The return value is 0 if there is nothing wrong with this setting.  Otherwise, it is one of the following
       constants:

       CRYPT_SALT_OK
             setting is a fully correct setting string.  This constant is guaranteed to equal 0.

       CRYPT_SALT_INVALID
             setting  is  not  a valid setting string; either it specifies a hashing method that is not known to
             this version of libxcrypt, or it specifies invalid parameters for the method.

       CRYPT_SALT_METHOD_DISABLED (Not implemented, yet)
             setting specifies a hashing method that is no longer allowed to be used at all; crypt will fail  if
             passed this setting.  Manual intervention will be required to reactivate the user's account.

       CRYPT_SALT_METHOD_LEGACY
             setting  specifies  a  hashing  method  that is no longer considered strong enough for use with new
             passphrases.   crypt  will  still  authenticate  a  passphrase  against  this   setting,   but   if
             authentication succeeds, the passphrase should be re-hashed using the currently preferred method.

       CRYPT_SALT_TOO_CHEAP (Not implemented, yet)
             setting  specifies  cost  parameters  that  are  considered too cheap for use with new passphrases.
             crypt will still authenticate a passphrase against this setting, but  if  authentication  succeeds,
             the passphrase should be re-hashed using the currently preferred method.

FEATURE TEST MACROS

       <crypt.h>  will define the macro CRYPT_CHECKSALT_AVAILABLE if crypt_checksalt is available in the current
       version of libxcrypt.

BUGS

       Since full configurability is not yet implemented, the  current  implementation  will  only  ever  return
       CRYPT_SALT_OK (0) or CRYPT_SALT_INVALID when invoked.

PORTABILITY NOTES

       The function crypt_checksalt is not part of any standard.  It was added to libxcrypt in version 4.3.0.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────┬───────────────┬─────────┐
       │ Interface       │ Attribute     │ Value   │
       ├─────────────────┼───────────────┼─────────┤
       │ crypt_checksalt │ Thread safety │ MT-Safe │
       └─────────────────┴───────────────┴─────────┘

SEE ALSO

       crypt(3), crypt_gensalt(3), crypt(5)

libxcrypt                                       November 8, 2018                              CRYPT_CHECKSALT(3)