encrypt(3)

1ENCRYPT(3)                 Linux Programmer's Manual                ENCRYPT(3)
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NAME

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

9       #define _XOPEN_SOURCE
10       #include <unistd.h>
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12       void encrypt(char block[64], int edflag);
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14       #define _XOPEN_SOURCE
15       #include <stdlib.h>
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17       void setkey(const char *key);
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19       #define _GNU_SOURCE
20       #include <crypt.h>
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22       void setkey_r(const char *key, struct crypt_data *data);
23       void encrypt_r(char *block, int edflag, struct crypt_data *data);
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25       Each of these requires linking with -lcrypt.
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DESCRIPTION

28       These  functions  encrypt  and  decrypt  64-bit messages.  The setkey()
29       function sets the key used by encrypt().  The key argument used here is
30       an  array  of  64 bytes, each of which has numerical value 1 or 0.  The
31       bytes key[n] where n=8*i-1 are  ignored,  so  that  the  effective  key
32       length is 56 bits.
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34       The  encrypt()  function modifies the passed buffer, encoding if edflag
35       is 0, and decoding if 1 is being passed.  Like the key  argument,  also
36       block  is  a  bit  vector  representation  of  the actual value that is
37       encoded.  The result is returned in that same vector.
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39       These two functions are not reentrant, that is, the key data is kept in
40       static storage.  The functions setkey_r() and encrypt_r() are the reen‐
41       trant versions.  They use the following structure to hold the key data:
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43           struct crypt_data {
44               char     keysched[16 * 8];
45               char     sb0[32768];
46               char     sb1[32768];
47               char     sb2[32768];
48               char     sb3[32768];
49               char     crypt_3_buf[14];
50               char     current_salt[2];
51               long int current_saltbits;
52               int      direction;
53               int      initialized;
54           };
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56       Before calling setkey_r() set data->initialized to zero.
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RETURN VALUE

59       These functions do not return any value.
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ERRORS

62       Set errno to zero before calling the above functions.  On  success,  it
63       is unchanged.
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65       ENOSYS The  function  is  not provided.  (For example because of former
66              USA export restrictions.)
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CONFORMING TO

69       The functions encrypt()  and  setkey()  conform  to  SVr4,  SUSv2,  and
70       POSIX.1-2001.   The functions encrypt_r() and setkey_r() are GNU exten‐
71       sions.
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NOTES

74       In glibc 2.2 these functions use the DES algorithm.
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EXAMPLE

77       You need to link with libcrypt to compile this example with glibc.   To
78       do  useful work the key[] and txt[] arrays must be filled with a useful
79       bit pattern.
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81       #define _XOPEN_SOURCE
82       #include <unistd.h>
83       #include <stdlib.h>
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85       int
86       main(void)
87       {
88           char key[64];      /* bit pattern for key */
89           char txt[64];      /* bit pattern for messages */
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91           setkey(key);
92           encrypt(txt, 0);   /* encode */
93           encrypt(txt, 1);   /* decode */
94       }
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COLOPHON

100       This page is part of release 3.22 of the Linux  man-pages  project.   A
101       description  of  the project, and information about reporting bugs, can
102       be found at http://www.kernel.org/doc/man-pages/.
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106                                  2003-04-04                        ENCRYPT(3)