1crypt(3EXT) Extended Library Functions crypt(3EXT)
2
6 crypt, setkey, encrypt, des_crypt, des_setkey, des_encrypt, run_setkey,
7 run_crypt, crypt_close - password and file encryption functions
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10 cc [ flag ... ] file ... -lcrypt [ library ... ]
11 #include <crypt.h>
12 char *crypt(const char *key, const char *salt);
14 void setkey(const char *key);
17 void encrypt(char *block, int flag);
20 char *des_crypt(const char *key, const char *salt);
23 void des_setkey(const char *key);
26 void des_encrypt(char *block, int flag);
29 int run_setkey(int *p, const char *key);
32 int run_crypt(long offset, char *buffer, unsigned int count,
35 int *p);
36 int crypt_close(int *p);
39
42 des_crypt() is the password encryption function. It is based on a one-
43 way hashing encryption algorithm with variations intended (among other
44 things) to frustrate use of hardware implementations of a key search.
45 key is a user's typed password. salt is a two-character string chosen
48 from the set [a-zA-Z0-9./]; this string is used to perturb the hashing
49 algorithm in one of 4096 different ways, after which the password is
50 used as the key to encrypt repeatedly a constant string. The returned
51 value points to the encrypted password. The first two characters are
52 the salt itself.
53 The des_setkey() and des_encrypt() entries provide (rather primitive)
56 access to the actual hashing algorithm. The argument of des_setkey() is
57 a character array of length 64 containing only the characters with
58 numerical value 0 and 1. If this string is divided into groups of 8,
59 the low-order bit in each group is ignored, thereby creating a 56-bit
60 key that is set into the machine. This key is the key that will be used
61 with the hashing algorithm to encrypt the string block with the func‐
62 tion des_encrypt().
63 The argument to the des_encrypt() entry is a character array of length
66 64 containing only the characters with numerical value 0 and 1. The
67 argument array is modified in place to a similar array representing the
68 bits of the argument after having been subjected to the hashing algo‐
69 rithm using the key set by des_setkey(). If flag is zero, the argument
70 is encrypted; if non-zero, it is decrypted.
71 Note that decryption is not provided in the international version of
74 crypt(). The international version is part of the C Development Set,
75 and the domestic version is part of the Security Administration Utili‐
76 ties. If decryption is attempted with the international version of
77 des_encrypt(), an error message is printed.
78 crypt(), setkey(), and encrypt() are front-end routines that invoke
81 des_crypt(), des_setkey(), and des_encrypt() respectively.
82 The routines run_setkey() and run_crypt() are designed for use by
85 applications that need cryptographic capabilities, such as ed(1) and
86 vi(1). run_setkey() establishes a two-way pipe connection with the
87 crypt utility, using key as the password argument. run_crypt() takes a
88 block of characters and transforms the cleartext or ciphertext into
89 their ciphertext or cleartext using the crypt utility. offset is the
90 relative byte position from the beginning of the file that the block of
91 text provided in block is coming from. count is the number of charac‐
92 ters in block, and connection is an array containing indices to a ta‐
93 ble of input and output file streams. When encryption is finished,
94 crypt_close() is used to terminate the connection with the crypt util‐
95 ity.
96 run_setkey() returns −1 if a connection with the crypt utility cannot
99 be established. This result will occur in international versions of the
100 UNIX system in which the crypt utility is not available. If a null key
101 is passed to run_setkey(), 0 is returned. Otherwise, 1 is returned.
102 run_crypt() returns −1 if it cannot write output or read input from
103 the pipe attached to crypt(). Otherwise it returns 0.
104 The program must be linked with the object file access routine library
107 libcrypt.a.
108
110 In the international version of crypt(), a flag argument of 1 to
111 encrypt() or des_encrypt() is not accepted, and errno is set to ENOSYS
112 to indicate that the functionality is not available.
113
115 See attributes(5) for descriptions of the following attributes:
116 ┌─────────────────────────────┬─────────────────────────────┐
121 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
122 ├─────────────────────────────┼─────────────────────────────┤
123 │MT-Level │Unsafe │
124 └─────────────────────────────┴─────────────────────────────┘
125
127 ed(1), login(1), passwd(1), vi(1), getpass(3C), passwd(4),
128 attributes(5)
129
131 The return value in crypt() points to static data that are overwritten
132 by each call.
133SunOS 5.11 3 Mar 2008 crypt(3EXT)