crypt(3) [minix man page]

CRYPT(3)						     Library Functions Manual							  CRYPT(3)

NAME

       crypt - one-way password encryption function

SYNOPSIS

       #define _MINIX_SOURCE 1
       #include <unistd.h>

       char *crypt(const char *key, const char *salt)

DESCRIPTION

       The  first  use	of  crypt()  is  to encrypt a password.  Its second use is to authenticate a shadow password.  In both cases crypt() calls
       pwdauth(8) to do the real work.

       Crypt() encrypts a password if called with a user typed key, and a salt whose first two characters  are	in  the  set  [./0-9A-Za-z].   The
       result  is  a  character  string in the [./0-9A-Za-z] alphabet of which the first two characters are equal to the salt, and the rest is the
       result of encrypting the key and the salt.

       If crypt() is called with a salt that has the form ##user then the key is encrypted and compared to the encrypted password of user  in  the
       shadow  password  file.	If they are equal then crypt() returns the ##user argument, if not then some other string is returned.	This trick
       assures that the normal way to authenticate a password still works:

	      if (strcmp(pw->pw_passwd, crypt(key, pw->pw_passwd))) ...

       If key is a null string, and the shadow password is a null string or the salt is a null string then  the  result  equals  salt.	 (This	is
       because the caller can't tell if a password field is empty in the shadow password file.)

       The key and salt are limited to 1024 bytes total including the null bytes.

FILES

       /usr/lib/pwdauth 	The password authentication program

SEE ALSO

       getpass(3), getpwent(3), passwd(5), pwdauth(8).

NOTES

       The result of an encryption is returned in a static array that is overwritten by each call.  The return value should not be modified.

AUTHOR

       Kees J. Bot (kjb@cs.vu.nl)

																	  CRYPT(3)

CRYPT(3)						     Library Functions Manual							  CRYPT(3)

NAME

       crypt, setkey, encrypt - DES encryption

SYNOPSIS

       char *crypt(key, salt)
       char *key, *salt;

       setkey(key)
       char *key;

       encrypt(block, edflag)
       char *block;

DESCRIPTION

       Crypt  is  the password encryption routine.  It is based on the NBS Data Encryption Standard, with variations intended (among other things)
       to frustrate use of hardware implementations of the DES for key search.

       The first argument to crypt is normally a user's typed password.  The second is a 2-character string chosen  from  the  set  [a-zA-Z0-9./].
       The  salt string is used to perturb the DES algorithm in one of 4096 different ways, after which the password is used as the key to encrypt
       repeatedly a constant string.  The returned value points to the encrypted password, in the same alphabet as the salt.  The first two  char-
       acters are the salt itself.

       The  other entries provide (rather primitive) access to the actual DES algorithm.  The argument of setkey is a character array of length 64
       containing only the characters with numerical value 0 and 1.  If this string is divided into groups of 8, the low-order bit in  each  group
       is ignored, leading to a 56-bit key which is set into the machine.

       The  argument  to  the  encrypt entry is likewise a character array of length 64 containing 0's and 1's.  The argument array is modified in
       place to a similar array representing the bits of the argument after having been subjected to the  DES  algorithm  using  the  key  set	by
       setkey.	The edflag flag is ignored; the argument can only be encrypted.

SEE ALSO

       passwd(1), passwd(5), login(1), getpass(3)

BUGS

       The return value points to static data whose content is overwritten by each call.

7th Edition							  August 12, 1986							  CRYPT(3)