]>
Commit | Line | Data |
---|---|---|
9dbc41d7 UM |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
827d17f0 MC |
5 | HMAC, |
6 | HMAC_CTX_new, | |
7 | HMAC_CTX_reset, | |
8 | HMAC_CTX_free, | |
9 | HMAC_Init, | |
10 | HMAC_Init_ex, | |
11 | HMAC_Update, | |
12 | HMAC_Final, | |
13 | HMAC_CTX_copy, | |
14 | HMAC_CTX_set_flags, | |
8d2b1819 MC |
15 | HMAC_CTX_get_md, |
16 | HMAC_size | |
827d17f0 | 17 | - HMAC message authentication code |
9dbc41d7 UM |
18 | |
19 | =head1 SYNOPSIS | |
20 | ||
21 | #include <openssl/hmac.h> | |
22 | ||
23 | unsigned char *HMAC(const EVP_MD *evp_md, const void *key, | |
24 | int key_len, const unsigned char *d, int n, | |
25 | unsigned char *md, unsigned int *md_len); | |
26 | ||
716854d7 RL |
27 | HMAC_CTX *HMAC_CTX_new(void); |
28 | int HMAC_CTX_reset(HMAC_CTX *ctx); | |
ff3fa48f | 29 | |
87d52468 | 30 | int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int key_len, |
1bc74519 | 31 | const EVP_MD *md, ENGINE *impl); |
87d52468 DSH |
32 | int HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, int len); |
33 | int HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len); | |
9dbc41d7 | 34 | |
716854d7 | 35 | void HMAC_CTX_free(HMAC_CTX *ctx); |
9dbc41d7 | 36 | |
827d17f0 MC |
37 | int HMAC_CTX_copy(HMAC_CTX *dctx, HMAC_CTX *sctx); |
38 | void HMAC_CTX_set_flags(HMAC_CTX *ctx, unsigned long flags); | |
39 | const EVP_MD *HMAC_CTX_get_md(const HMAC_CTX *ctx); | |
40 | ||
8d2b1819 MC |
41 | size_t HMAC_size(const HMAC_CTX *e); |
42 | ||
98186eb4 VD |
43 | Deprecated: |
44 | ||
45 | #if OPENSSL_API_COMPAT < 0x10100000L | |
46 | int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len, | |
47 | const EVP_MD *md); | |
48 | #endif | |
49 | ||
9dbc41d7 UM |
50 | =head1 DESCRIPTION |
51 | ||
52 | HMAC is a MAC (message authentication code), i.e. a keyed hash | |
53 | function used for message authentication, which is based on a hash | |
54 | function. | |
55 | ||
56 | HMAC() computes the message authentication code of the B<n> bytes at | |
57 | B<d> using the hash function B<evp_md> and the key B<key> which is | |
58 | B<key_len> bytes long. | |
59 | ||
60 | It places the result in B<md> (which must have space for the output of | |
61 | the hash function, which is no more than B<EVP_MAX_MD_SIZE> bytes). | |
62 | If B<md> is NULL, the digest is placed in a static array. The size of | |
63 | the output is placed in B<md_len>, unless it is B<NULL>. | |
64 | ||
65 | B<evp_md> can be EVP_sha1(), EVP_ripemd160() etc. | |
9dbc41d7 | 66 | |
716854d7 | 67 | HMAC_CTX_new() creates a new HMAC_CTX in heap memory. |
ff3fa48f | 68 | |
716854d7 RL |
69 | HMAC_CTX_reset() zeroes an existing B<HMAC_CTX> and associated |
70 | resources, making it suitable for new computations as if it was newly | |
71 | created with HMAC_CTX_new(). | |
72 | ||
73 | HMAC_CTX_free() erases the key and other data from the B<HMAC_CTX>, | |
74 | releases any associated resources and finally frees the B<HMAC_CTX> | |
75 | itself. | |
ff3fa48f | 76 | |
9dbc41d7 UM |
77 | The following functions may be used if the message is not completely |
78 | stored in memory: | |
79 | ||
80 | HMAC_Init() initializes a B<HMAC_CTX> structure to use the hash | |
ff3fa48f BL |
81 | function B<evp_md> and the key B<key> which is B<key_len> bytes |
82 | long. It is deprecated and only included for backward compatibility | |
83 | with OpenSSL 0.9.6b. | |
84 | ||
bd19d1aa DSH |
85 | HMAC_Init_ex() initializes or reuses a B<HMAC_CTX> structure to use the hash |
86 | function B<evp_md> and key B<key>. If both are NULL (or B<evp_md> is the same | |
87 | as the previous digest used by B<ctx> and B<key> is NULL) the existing key is | |
88 | reused. B<ctx> must have been created with HMAC_CTX_new() before the first use | |
89 | of an B<HMAC_CTX> in this function. B<N.B. HMAC_Init() had this undocumented | |
90 | behaviour in previous versions of OpenSSL - failure to switch to HMAC_Init_ex() | |
91 | in programs that expect it will cause them to stop working>. | |
92 | ||
1a627771 | 93 | B<NOTE:> If HMAC_Init_ex() is called with B<key> NULL and B<evp_md> is not the |
bd19d1aa | 94 | same as the previous digest used by B<ctx> then an error is returned |
1a627771 | 95 | because reuse of an existing key with a different digest is not supported. |
9dbc41d7 UM |
96 | |
97 | HMAC_Update() can be called repeatedly with chunks of the message to | |
98 | be authenticated (B<len> bytes at B<data>). | |
99 | ||
100 | HMAC_Final() places the message authentication code in B<md>, which | |
101 | must have space for the hash function output. | |
102 | ||
827d17f0 MC |
103 | HMAC_CTX_copy() copies all of the internal state from B<sctx> into B<dctx>. |
104 | ||
105 | HMAC_CTX_set_flags() applies the specified flags to the internal EVP_MD_CTXs. | |
106 | These flags have the same meaning as for L<EVP_MD_CTX_set_flags(3)>. | |
107 | ||
108 | HMAC_CTX_get_md() returns the EVP_MD that has previously been set for the | |
109 | supplied HMAC_CTX. | |
110 | ||
8d2b1819 MC |
111 | HMAC_size() returns the length in bytes of the underlying hash function output. |
112 | ||
9dbc41d7 UM |
113 | =head1 RETURN VALUES |
114 | ||
87d52468 DSH |
115 | HMAC() returns a pointer to the message authentication code or NULL if |
116 | an error occurred. | |
9dbc41d7 | 117 | |
716854d7 RL |
118 | HMAC_CTX_new() returns a pointer to a new B<HMAC_CTX> on success or |
119 | B<NULL> if an error occurred. | |
120 | ||
827d17f0 MC |
121 | HMAC_CTX_reset(), HMAC_Init_ex(), HMAC_Update(), HMAC_Final() and |
122 | HMAC_CTX_copy() return 1 for success or 0 if an error occurred. | |
87d52468 | 123 | |
827d17f0 MC |
124 | HMAC_CTX_get_md() return the EVP_MD previously set for the supplied HMAC_CTX or |
125 | NULL if no EVP_MD has been set. | |
9dbc41d7 | 126 | |
8d2b1819 MC |
127 | HMAC_size() returns the length in bytes of the underlying hash function output |
128 | or zero on error. | |
129 | ||
9dbc41d7 UM |
130 | =head1 CONFORMING TO |
131 | ||
132 | RFC 2104 | |
133 | ||
134 | =head1 SEE ALSO | |
135 | ||
b97fdb57 | 136 | L<SHA1(3)>, L<evp(7)> |
9dbc41d7 UM |
137 | |
138 | =head1 HISTORY | |
139 | ||
827d17f0 | 140 | HMAC_CTX_init() was replaced with HMAC_CTX_reset() in OpenSSL versions 1.1.0. |
716854d7 | 141 | |
827d17f0 | 142 | HMAC_CTX_cleanup() existed in OpenSSL versions before 1.1.0. |
716854d7 | 143 | |
827d17f0 MC |
144 | HMAC_CTX_new(), HMAC_CTX_free() and HMAC_CTX_get_md() are new in OpenSSL version |
145 | 1.1.0. | |
9b6c0070 | 146 | |
87d52468 | 147 | HMAC_Init_ex(), HMAC_Update() and HMAC_Final() did not return values in |
fb552ac6 | 148 | versions of OpenSSL before 1.0.0. |
87d52468 | 149 | |
e2f92610 RS |
150 | =head1 COPYRIGHT |
151 | ||
152 | Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. | |
153 | ||
154 | Licensed under the OpenSSL license (the "License"). You may not use | |
155 | this file except in compliance with the License. You can obtain a copy | |
156 | in the file LICENSE in the source distribution or at | |
157 | L<https://www.openssl.org/source/license.html>. | |
158 | ||
159 | =cut |