1ENCRYPT(3) Linux Programmer's Manual ENCRYPT(3)
2
6 encrypt, setkey, encrypt_r, setkey_r - encrypt 64-bit messages
7
9 #define _XOPEN_SOURCE /* See feature_test_macros(7) */
10 #include <unistd.h>
11 void encrypt(char block[64], int edflag);
13 #define _XOPEN_SOURCE /* See feature_test_macros(7) */
15 #include <stdlib.h>
16 void setkey(const char *key);
18 #define _GNU_SOURCE /* See feature_test_macros(7) */
20 #include <crypt.h>
21 void setkey_r(const char *key, struct crypt_data *data);
23 void encrypt_r(char *block, int edflag, struct crypt_data *data);
24 Each of these requires linking with -lcrypt.
26
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.
33 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.
38 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:
42 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 };
55 Before calling setkey_r() set data->initialized to zero.
57
59 These functions do not return any value.
60
62 Set errno to zero before calling the above functions. On success, it
63 is unchanged.
64 ENOSYS The function is not provided. (For example because of former
66 USA export restrictions.)
67
69 For an explanation of the terms used in this section, see
70 attributes(7).
71 ┌────────────────────────┬───────────────┬──────────────────────┐
73 │Interface │ Attribute │ Value │
74 ├────────────────────────┼───────────────┼──────────────────────┤
75 │encrypt(), setkey() │ Thread safety │ MT-Unsafe race:crypt │
76 ├────────────────────────┼───────────────┼──────────────────────┤
77 │encrypt_r(), setkey_r() │ Thread safety │ MT-Safe │
78 └────────────────────────┴───────────────┴──────────────────────┘
80 encrypt(), setkey(): POSIX.1-2001, POSIX.1-2008, SUS, SVr4.
81 The functions encrypt_r() and setkey_r() are GNU extensions.
83
85 Availability in glibc
86 See crypt(3).
87 Features in glibc
89 In glibc 2.2, these functions use the DES algorithm.
90
92 #define _XOPEN_SOURCE
93 #include <stdio.h>
94 #include <stdlib.h>
95 #include <unistd.h>
96 #include <crypt.h>
97 int
99 main(void)
100 {
101 char key[64];
102 char orig[9] = "eggplant";
103 char buf[64];
104 char txt[9];
105 int i, j;
106 for (i = 0; i < 64; i++) {
108 key[i] = rand() & 1;
109 }
110 for (i = 0; i < 8; i++) {
112 for (j = 0; j < 8; j++) {
113 buf[i * 8 + j] = orig[i] >> j & 1;
114 }
115 setkey(key);
116 }
117 printf("Before encrypting: %s\n", orig);
118 encrypt(buf, 0);
120 for (i = 0; i < 8; i++) {
121 for (j = 0, txt[i] = '\0'; j < 8; j++) {
122 txt[i] |= buf[i * 8 + j] << j;
123 }
124 txt[8] = '\0';
125 }
126 printf("After encrypting: %s\n", txt);
127 encrypt(buf, 1);
129 for (i = 0; i < 8; i++) {
130 for (j = 0, txt[i] = '\0'; j < 8; j++) {
131 txt[i] |= buf[i * 8 + j] << j;
132 }
133 txt[8] = '\0';
134 }
135 printf("After decrypting: %s\n", txt);
136 exit(EXIT_SUCCESS);
137 }
138
140 cbc_crypt(3), crypt(3), ecb_crypt(3),
141
143 This page is part of release 4.16 of the Linux man-pages project. A
144 description of the project, information about reporting bugs, and the
145 latest version of this page, can be found at
146 https://www.kernel.org/doc/man-pages/.
147 2018-04-30 ENCRYPT(3)