crypt(3EXT)						    Extended Library Functions						       crypt(3EXT)

NAME

       crypt, setkey, encrypt, des_crypt, des_setkey, des_encrypt, run_setkey, run_crypt, crypt_close - password and file encryption functions

SYNOPSIS

       cc [ flag ... ] file ... -lcrypt [ library ... ]
       #include <crypt.h>

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

       void setkey(const char *key);

       void encrypt(char *block, int flag);

       char *des_crypt(const char *key, const char *salt);

       void des_setkey(const char *key);

       void des_encrypt(char *block, int flag);

       int run_setkey(int *p, const char *key);

       int run_crypt(long offset, char *buffer, unsigned int count,
	    int *p);

       int crypt_close(int *p);

DESCRIPTION

       des_crypt()  is	the  password  encryption  function. It is based on a one-way hashing encryption algorithm with variations intended (among
       other things) to frustrate use of hardware implementations of a key search.

       key is a user's typed password. salt is a two-character string chosen from the set [a-zA-Z0-9./]; this string is used to perturb the  hash-
       ing  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. The first two characters are the salt itself.

       The des_setkey() and des_encrypt() entries provide (rather primitive) access to the actual hashing algorithm. The argument of  des_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, thereby creating a 56-bit key that is set into the machine. This key is the key  that  will	be
       used with the hashing algorithm to encrypt the string block with the function des_encrypt().

       The  argument to the des_encrypt() entry is a character array of length 64 containing only the characters with numerical value 0 and 1. The
       argument array is modified in place to a similar array representing the bits of the argument after having been  subjected  to  the  hashing
       algorithm using the key set by des_setkey(). If	flag is zero, the argument is encrypted; if non-zero, it is decrypted.

       Note  that  decryption is not provided in the international version of crypt(). The international version is part of the C Development Set,
       and the domestic version is part of the Security Administration Utilities.  If decryption is attempted with the	international  version	of
       des_encrypt(), an error message is printed.

       crypt(), setkey(), and encrypt() are front-end routines that invoke des_crypt(), des_setkey(), and des_encrypt() respectively.

       The  routines  run_setkey()  and  run_crypt()  are designed for use by applications that need cryptographic capabilities, such as ed(1) and
       vi(1). run_setkey() establishes a two-way pipe connection with the crypt utility, using key as the password argument. run_crypt()  takes  a
       block  of characters and transforms the cleartext or ciphertext into their ciphertext or cleartext using the crypt utility.   offset is the
       relative byte position from the beginning of the file that the block of text provided in block is coming from. count is the number of char-
       acters in block, and connection	is an array containing indices to a table of input and output file streams.   When encryption is finished,
       crypt_close() is used to terminate the connection with the crypt utility.

       run_setkey() returns  -1 if a connection with the crypt utility cannot be established. This result will occur in international versions	of
       the  UNIX  system  in  which the crypt utility is not available.  If a null key is passed to run_setkey(), 0 is returned.  Otherwise,  1 is
       returned. run_crypt() returns  -1 if it cannot write output or read input from the pipe attached to crypt(). Otherwise it returns  0.

       The program must be linked with the object file access routine library libcrypt.a.

RETURN VALUES

       In the international version of crypt(), a flag argument of  1 to encrypt() or des_encrypt() is not accepted, and errno is set to ENOSYS to
       indicate that the functionality is not available.

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ed(1), login(1), passwd(1), vi(1), getpass(3C), passwd(4), attributes(5)

NOTES

       The return value in crypt() points to static data that are overwritten by each call.

SunOS 5.11							    3 Mar 2008							       crypt(3EXT)