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1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
2  * All rights reserved.
3  *
4  * This package is an SSL implementation written
5  * by Eric Young (eay@cryptsoft.com).
6  * The implementation was written so as to conform with Netscapes SSL.
7  *
8  * This library is free for commercial and non-commercial use as long as
9  * the following conditions are aheared to.  The following conditions
10  * apply to all code found in this distribution, be it the RC4, RSA,
11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
12  * included with this distribution is covered by the same copyright terms
13  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
14  *
15  * Copyright remains Eric Young's, and as such any Copyright notices in
16  * the code are not to be removed.
17  * If this package is used in a product, Eric Young should be given attribution
18  * as the author of the parts of the library used.
19  * This can be in the form of a textual message at program startup or
20  * in documentation (online or textual) provided with the package.
21  *
22  * Redistribution and use in source and binary forms, with or without
23  * modification, are permitted provided that the following conditions
24  * are met:
25  * 1. Redistributions of source code must retain the copyright
26  *    notice, this list of conditions and the following disclaimer.
27  * 2. Redistributions in binary form must reproduce the above copyright
28  *    notice, this list of conditions and the following disclaimer in the
29  *    documentation and/or other materials provided with the distribution.
30  * 3. All advertising materials mentioning features or use of this software
31  *    must display the following acknowledgement:
32  *    "This product includes cryptographic software written by
33  *     Eric Young (eay@cryptsoft.com)"
34  *    The word 'cryptographic' can be left out if the rouines from the library
35  *    being used are not cryptographic related :-).
36  * 4. If you include any Windows specific code (or a derivative thereof) from
37  *    the apps directory (application code) you must include an acknowledgement:
38  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
39  *
40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50  * SUCH DAMAGE.
51  *
52  * The licence and distribution terms for any publically available version or
53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
54  * copied and put under another distribution licence
55  * [including the GNU Public Licence.] */
56 
57 #ifndef OPENSSL_HEADER_HMAC_H
58 #define OPENSSL_HEADER_HMAC_H
59 
60 #include <openssl/base.h>
61 
62 #include <openssl/digest.h>
63 
64 #if defined(__cplusplus)
65 extern "C" {
66 #endif
67 
68 
69 // HMAC contains functions for constructing PRFs from Merkle–Damgård hash
70 // functions using HMAC.
71 
72 
73 // One-shot operation.
74 
75 // HMAC calculates the HMAC of |data_len| bytes of |data|, using the given key
76 // and hash function, and writes the result to |out|. On entry, |out| must
77 // contain at least |EVP_MD_size| bytes of space. The actual length of the
78 // result is written to |*out_len|. An output size of |EVP_MAX_MD_SIZE| will
79 // always be large enough. It returns |out| or NULL on error.
80 OPENSSL_EXPORT uint8_t *HMAC(const EVP_MD *evp_md, const void *key,
81                              size_t key_len, const uint8_t *data,
82                              size_t data_len, uint8_t *out,
83                              unsigned int *out_len);
84 
85 
86 // Incremental operation.
87 
88 // HMAC_CTX_init initialises |ctx| for use in an HMAC operation. It's assumed
89 // that HMAC_CTX objects will be allocated on the stack thus no allocation
90 // function is provided.
91 OPENSSL_EXPORT void HMAC_CTX_init(HMAC_CTX *ctx);
92 
93 // HMAC_CTX_new allocates and initialises a new |HMAC_CTX| and returns it, or
94 // NULL on allocation failure. The caller must use |HMAC_CTX_free| to release
95 // the resulting object.
96 OPENSSL_EXPORT HMAC_CTX *HMAC_CTX_new(void);
97 
98 // HMAC_CTX_cleanup frees data owned by |ctx|. It does not free |ctx| itself.
99 OPENSSL_EXPORT void HMAC_CTX_cleanup(HMAC_CTX *ctx);
100 
101 // HMAC_CTX_free calls |HMAC_CTX_cleanup| and then frees |ctx| itself.
102 OPENSSL_EXPORT void HMAC_CTX_free(HMAC_CTX *ctx);
103 
104 // HMAC_Init_ex sets up an initialised |HMAC_CTX| to use |md| as the hash
105 // function and |key| as the key. For a non-initial call, |md| may be NULL, in
106 // which case the previous hash function will be used. If the hash function has
107 // not changed and |key| is NULL, |ctx| reuses the previous key. It returns one
108 // on success or zero on allocation failure.
109 //
110 // WARNING: NULL and empty keys are ambiguous on non-initial calls. Passing NULL
111 // |key| but repeating the previous |md| reuses the previous key rather than the
112 // empty key.
113 OPENSSL_EXPORT int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, size_t key_len,
114                                 const EVP_MD *md, ENGINE *impl);
115 
116 // HMAC_Update hashes |data_len| bytes from |data| into the current HMAC
117 // operation in |ctx|. It returns one.
118 OPENSSL_EXPORT int HMAC_Update(HMAC_CTX *ctx, const uint8_t *data,
119                                size_t data_len);
120 
121 // HMAC_Final completes the HMAC operation in |ctx| and writes the result to
122 // |out| and the sets |*out_len| to the length of the result. On entry, |out|
123 // must contain at least |HMAC_size| bytes of space. An output size of
124 // |EVP_MAX_MD_SIZE| will always be large enough. It returns one on success or
125 // zero on allocation failure.
126 OPENSSL_EXPORT int HMAC_Final(HMAC_CTX *ctx, uint8_t *out,
127                               unsigned int *out_len);
128 
129 
130 // Utility functions.
131 
132 // HMAC_size returns the size, in bytes, of the HMAC that will be produced by
133 // |ctx|. On entry, |ctx| must have been setup with |HMAC_Init_ex|.
134 OPENSSL_EXPORT size_t HMAC_size(const HMAC_CTX *ctx);
135 
136 // HMAC_CTX_copy_ex sets |dest| equal to |src|. On entry, |dest| must have been
137 // initialised by calling |HMAC_CTX_init|. It returns one on success and zero
138 // on error.
139 OPENSSL_EXPORT int HMAC_CTX_copy_ex(HMAC_CTX *dest, const HMAC_CTX *src);
140 
141 // HMAC_CTX_reset calls |HMAC_CTX_cleanup| followed by |HMAC_CTX_init|.
142 OPENSSL_EXPORT void HMAC_CTX_reset(HMAC_CTX *ctx);
143 
144 
145 // Deprecated functions.
146 
147 OPENSSL_EXPORT int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len,
148                              const EVP_MD *md);
149 
150 // HMAC_CTX_copy calls |HMAC_CTX_init| on |dest| and then sets it equal to
151 // |src|. On entry, |dest| must /not/ be initialised for an operation with
152 // |HMAC_Init_ex|. It returns one on success and zero on error.
153 OPENSSL_EXPORT int HMAC_CTX_copy(HMAC_CTX *dest, const HMAC_CTX *src);
154 
155 
156 // Private functions
157 
158 struct hmac_ctx_st {
159   const EVP_MD *md;
160   EVP_MD_CTX md_ctx;
161   EVP_MD_CTX i_ctx;
162   EVP_MD_CTX o_ctx;
163 } /* HMAC_CTX */;
164 
165 
166 #if defined(__cplusplus)
167 }  // extern C
168 
169 #if !defined(BORINGSSL_NO_CXX)
170 extern "C++" {
171 
172 BSSL_NAMESPACE_BEGIN
173 
174 BORINGSSL_MAKE_DELETER(HMAC_CTX, HMAC_CTX_free)
175 
176 using ScopedHMAC_CTX =
177     internal::StackAllocated<HMAC_CTX, void, HMAC_CTX_init, HMAC_CTX_cleanup>;
178 
179 BSSL_NAMESPACE_END
180 
181 }  // extern C++
182 #endif
183 
184 #endif
185 
186 #endif  // OPENSSL_HEADER_HMAC_H
187