NAME

       encrypt, setkey, encrypt_r, setkey_r - encrypt 64-bit messages

LIBRARY

       Password hashing library (libcrypt, -lcrypt)

SYNOPSIS

       #define _XOPEN_SOURCE       /* See feature_test_macros(7) */
       #include <unistd.h>

       [[deprecated]] void encrypt(char block[64], int edflag);

       #define _XOPEN_SOURCE       /* See feature_test_macros(7) */
       #include <stdlib.h>

       [[deprecated]] void setkey(const char *key);

       #define _GNU_SOURCE         /* See feature_test_macros(7) */
       #include <crypt.h>

       [[deprecated]] void setkey_r(const char *key, struct crypt_data *data);
       [[deprecated]] void encrypt_r(char *block, int edflag,
                                     struct crypt_data *data);

DESCRIPTION

       These  functions  encrypt  and  decrypt  64-bit  messages.   The  setkey()  function sets the key used by
       encrypt().  The key argument used here is an array of 64 bytes, each of which has numerical value 1 or 0.
       The bytes key[n] where n=8*i-1 are ignored, so that the effective key length is 56 bits.

       The  encrypt()  function  modifies the passed buffer, encoding if edflag is 0, and decoding if 1 is being
       passed.  Like the key argument, also block is a bit vector representation of the  actual  value  that  is
       encoded.  The result is returned in that same vector.

       These  two  functions  are not reentrant, that is, the key data is kept in static storage.  The functions
       setkey_r() and encrypt_r() are the reentrant versions.  They use the following structure to hold the  key
       data:

           struct crypt_data {
               char keysched[16 * 8];
               char sb0[32768];
               char sb1[32768];
               char sb2[32768];
               char sb3[32768];
               char crypt_3_buf[14];
               char current_salt[2];
               long current_saltbits;
               int  direction;
               int  initialized;
           };

       Before calling setkey_r() set data->initialized to zero.

RETURN VALUE

       These functions do not return any value.

ERRORS

       Set errno to zero before calling the above functions.  On success, errno is unchanged.

       ENOSYS The function is not provided.  (For example because of former USA export restrictions.)

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌─────────────────────────────────────────────────────────────────┬───────────────┬──────────────────────┐
       │Interface                                                        │ Attribute     │ Value                │
       ├─────────────────────────────────────────────────────────────────┼───────────────┼──────────────────────┤
       │encrypt(), setkey()                                              │ Thread safety │ MT-Unsafe race:crypt │
       ├─────────────────────────────────────────────────────────────────┼───────────────┼──────────────────────┤
       │encrypt_r(), setkey_r()                                          │ Thread safety │ MT-Safe              │
       └─────────────────────────────────────────────────────────────────┴───────────────┴──────────────────────┘

STANDARDS

       encrypt()
       setkey()
              POSIX.1-2008.

       encrypt_r()
       setkey_r()
              None.

HISTORY

       Removed in glibc 2.28.

       Because  they  employ  the  DES  block cipher, which is no longer considered secure, these functions were
       removed from glibc.  Applications should switch to a modern cryptography library, such as libgcrypt.

       encrypt()
       setkey()
              POSIX.1-2001, SUS, SVr4.

   Availability in glibc
       See crypt(3).

   Features in glibc
       In glibc 2.2, these functions use the DES algorithm.

EXAMPLES

       #define _XOPEN_SOURCE
       #include <crypt.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <unistd.h>

       int
       main(void)
       {
           char key[64];
           char orig[9] = "eggplant";
           char buf[64];
           char txt[9];

           for (size_t i = 0; i < 64; i++) {
               key[i] = rand() & 1;
           }

           for (size_t i = 0; i < 8; i++) {
               for (size_t j = 0; j < 8; j++) {
                   buf[i * 8 + j] = orig[i] >> j & 1;
               }
               setkey(key);
           }
           printf("Before encrypting: %s\n", orig);

           encrypt(buf, 0);
           for (size_t i = 0; i < 8; i++) {
               for (size_t j = 0, txt[i] = '\0'; j < 8; j++) {
                   txt[i] |= buf[i * 8 + j] << j;
               }
               txt[8] = '\0';
           }
           printf("After encrypting:  %s\n", txt);

           encrypt(buf, 1);
           for (size_t i = 0; i < 8; i++) {
               for (size_t j = 0, txt[i] = '\0'; j < 8; j++) {
                   txt[i] |= buf[i * 8 + j] << j;
               }
               txt[8] = '\0';
           }
           printf("After decrypting:  %s\n", txt);
           exit(EXIT_SUCCESS);
       }

SEE ALSO

       cbc_crypt(3), crypt(3), ecb_crypt(3)