# phpman > man > crypt_checksalt(3)

[CRYPT_CHECKSALT(3)](https://www.chedong.com/phpMan.php/man/CRYPTCHECKSALT/3/markdown)       BSD Library Functions Manual       [CRYPT_CHECKSALT(3)](https://www.chedong.com/phpMan.php/man/CRYPTCHECKSALT/3/markdown)

## 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)](https://www.chedong.com/phpMan.php/man/login/1/markdown) 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 au‐
           thentication 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)](https://www.chedong.com/phpMan.php/man/attributes/7/markdown).




     ┌────────────────┬───────────────┬─────────┐
     │**Interface**       │ **Attribute**     │ **Value**   │
     ├────────────────┼───────────────┼─────────┤
     │**crypt**___**checksalt** │ Thread safety │ MT-Safe │
     └────────────────┴───────────────┴─────────┘

## SEE ALSO
     [crypt(3)](https://www.chedong.com/phpMan.php/man/crypt/3/markdown), [crypt_gensalt(3)](https://www.chedong.com/phpMan.php/man/cryptgensalt/3/markdown), [crypt(5)](https://www.chedong.com/phpMan.php/man/crypt/5/markdown)

libxcrypt                      November 8, 2018                      libxcrypt