Tribblix: manual page: crypt

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(5).

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