LIBPASSWDQC(3)

NAME
passwdqc_params_reset, passwdqc_params_load, passwdqc_params_parse, passwdqc_params_free, passwdqc_check, passwdqc_random - password strength checking functions

LIBRARY
Password strength checking library (libpasswdqc, -lpasswdqc)

SYNOPSIS
#include <passwdqc.h>

    typedef struct {
    	passwdqc_params_qc_t qc;
    	passwdqc_params_pam_t pam;
    } passwdqc_params_t;

void
passwdqc_params_reset(passwdqc_params_t *params);
int
passwdqc_params_load(passwdqc_params_t *params, char **reason, const char *pathname);
int
passwdqc_params_parse(passwdqc_params_t *params, char **reason, int argc, const char *const *argv);
void
passwdqc_params_free(passwdqc_params_t *params);
const char *
passwdqc_check(const passwdqc_params_qc_t *params, const char *newpass, const char *oldpass, const struct passwd *pw);
char *
passwdqc_random(const passwdqc_params_qc_t *params);

DESCRIPTION
The passwdqc_params_reset() function initializes the passwdqc_params_t structure specified by params argument to compile-time defaults.

The passwdqc_params_load() function fills in the passwdqc_params_t structure specified by params argument according to the configuration options listed in the file specified by pathname argument. When the passwdqc_params_t structure is no longer needed, the memory allocated by this function should be released using passwdqc_params_free().

The passwdqc_params_parse() function fills in the passwdqc_params_t structure specified by params argument according to the configuration options specified by argc and argv arguments. When the passwdqc_params_t structure is no longer needed, the memory allocated by this function should be released using passwdqc_params_free().

The passwdqc_params_free() function frees the memory allocated by passwdqc_params_load() and passwdqc_params_parse() functions when filling in the passwdqc_params_t structure specified by params argument.

The passwdqc_check() function checks the quality of the passphrase specified by newpass argument according to the configuration specified by params argument. If an optional old passphrase is specified by oldpass argument, newpass is additionally checked against oldpass for similarity. If an optional passwd record is specified by pw argument, newpass is additionally checked whether it is based on the personal login information in the passwd record.

The passwdqc_random() function generates a random passphrase according to the configuration specified by params argument.

RETURN VALUES
The passwdqc_params_reset() and passwdqc_params_free() functions do not return a value.

Upon successful completion the passwdqc_params_load() and passwdqc_params_parse() functions return 0. Otherwise, -1 is returned and a pointer to dynamically allocated memory containing the error string is assigned to *reason. This memory should be released using free(3) when no longer needed.

Upon successful completion the passwdqc_check() function returns NULL. Otherwise, a string describing the error is returned. The returned string is statically allocated and valid for the lifetime of the program.

Upon successful completion the passwdqc_random() function returns a dynamically allocated string containing the generated passphrase. Otherwise, NULL is returned. The string should be released using free(3) when no longer needed.

FILES
/etc/passwdqc.conf (not read unless this suggested file location is specified with the pathname argument or with config=/etc/passwdqc.conf configuration option).

EXAMPLES
The following example shows how to use the libpasswdqc library with system configuration options to check a passphrase.

    #include <passwdqc.h>
    #include <stdbool.h>
    #include <stdlib.h>
    #include <stdio.h>
    bool
    check(const char *newpass, const char *oldpass, const struct passwd *pw)
    {
      static const char config[] = "/etc/passwdqc.conf";
      char *parse_reason;
      const char *check_result = "";
      passwdqc_params_t params;
      passwdqc_params_reset(&params);
      if (passwdqc_params_load(&params, &parse_reason, config)) {
        fprintf(stderr, "passwdqc_params_load: %s\n",
          parse_reason ? parse_reason : "Out of memory");
        free(parse_reason);
        goto out;
      }
      check_result = passwdqc_check(&params.qc, newpass, oldpass, pw);
      if (check_result)
        fprintf(stderr, "passwdqc_check: %s\n", check_result);
    out:
      passwdqc_params_free(&params);
      return !check_result;
    }

SEE ALSO
passwdqc.conf(5), pwqcheck(1), pwqgen(1), pam_passwdqc(8).

https://www.openwall.com/passwdqc/

HISTORY
The pam_passwdqc module was written for Openwall GNU/*/Linux by Solar Designer. The libpasswdqc library was originally written for ALT GNU/*/Linux by Dmitry V. Levin, reusing code from pam_passwdqc. The passwdqc_params_free() function was added in version 2.0.0 by Solar Designer.

AUTHORS
This manual page was written by Dmitry V. Levin.