CRYPT_GENSALT(3C) Standard C Library Functions CRYPT_GENSALT(3C)


NAME


crypt_gensalt - generate salt string for string encoding

SYNOPSIS


#include <crypt.h>

char *crypt_gensalt(const char *oldsalt, const struct passwd *userinfo);


DESCRIPTION


The crypt_gensalt() function generates the salt string required by
crypt(3C).


If oldsalt is NULL, crypt_gensalt() uses the algorithm defined by
CRYPT_DEFAULT in /etc/security/policy.conf. See policy.conf(4).


If oldsalt is non-null, crypt_gensalt() determines if the algorithm
specified by oldsalt is allowable by checking the CRYPT_ALGORITHMS_ALLOW
and CRYPT_ALGORITHMS_DEPRECATE variables in /etc/security/policy.conf. If
the algorithm is allowed, crypt_gensalt() loads the appropriate shared
library and calls crypt_gensalt_impl(3C). If the algorithm is not allowed
or there is no entry for it in crypt.conf, crypt_gensalt() uses the
default algorithm.


The mechanism just described provides a means to migrate users to new
password hashing algorithms when the password is changed.

RETURN VALUES


Upon successful completion, crypt_gensalt() returns a pointer to the new
salt. Otherwise a null pointer is returned and errno is set to indicate
the error.

ERRORS


The crypt_gensalt() function will fail if:

EINVAL
The configuration file crypt.conf contains an invalid entry.


ELIBACC
The required shared library was not found.


ENOMEM
There is insufficient memory to perform hashing.


USAGE


The value returned by crypt_gensalt() points to a null-terminated string.
The caller of crypt_gensalt() is responsible for calling free(3C).


Applications dealing with user authentication and password changing
should not call crypt_gensalt() directly but should instead call the
appropriate pam(3PAM) functions.

ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Evolving |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO


passwd(1), crypt(3C), crypt_genhash_impl(3C), crypt_gensalt_impl(3C),
getpassphrase(3C), malloc(3C), pam(3PAM), crypt.conf(4), passwd(4),
policy.conf(4), attributes(5)


June 10, 2002 CRYPT_GENSALT(3C)