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 #include <openssl/hmac.h>
58 
59 #include <assert.h>
60 #include <string.h>
61 
62 #include <openssl/mem.h>
63 
64 
HMAC(const EVP_MD * evp_md,const void * key,size_t key_len,const uint8_t * data,size_t data_len,uint8_t * out,unsigned int * out_len)65 uint8_t *HMAC(const EVP_MD *evp_md, const void *key, size_t key_len,
66               const uint8_t *data, size_t data_len, uint8_t *out,
67               unsigned int *out_len) {
68   HMAC_CTX ctx;
69   static uint8_t static_out_buffer[EVP_MAX_MD_SIZE];
70 
71   /* OpenSSL has traditionally supported using a static buffer if |out| is
72    * NULL. We maintain that but don't document it. This behaviour should be
73    * considered to be deprecated. */
74   if (out == NULL) {
75     out = static_out_buffer;
76   }
77 
78   HMAC_CTX_init(&ctx);
79   if (!HMAC_Init_ex(&ctx, key, key_len, evp_md, NULL) ||
80       !HMAC_Update(&ctx, data, data_len) ||
81       !HMAC_Final(&ctx, out, out_len)) {
82     out = NULL;
83   }
84 
85   HMAC_CTX_cleanup(&ctx);
86   return out;
87 }
88 
HMAC_CTX_init(HMAC_CTX * ctx)89 void HMAC_CTX_init(HMAC_CTX *ctx) {
90   ctx->md = NULL;
91   EVP_MD_CTX_init(&ctx->i_ctx);
92   EVP_MD_CTX_init(&ctx->o_ctx);
93   EVP_MD_CTX_init(&ctx->md_ctx);
94 }
95 
HMAC_CTX_cleanup(HMAC_CTX * ctx)96 void HMAC_CTX_cleanup(HMAC_CTX *ctx) {
97   EVP_MD_CTX_cleanup(&ctx->i_ctx);
98   EVP_MD_CTX_cleanup(&ctx->o_ctx);
99   EVP_MD_CTX_cleanup(&ctx->md_ctx);
100   OPENSSL_cleanse(ctx, sizeof(HMAC_CTX));
101 }
102 
HMAC_Init_ex(HMAC_CTX * ctx,const void * key,size_t key_len,const EVP_MD * md,ENGINE * impl)103 int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, size_t key_len,
104                  const EVP_MD *md, ENGINE *impl) {
105   if (md == NULL) {
106     md = ctx->md;
107   }
108 
109   /* If either |key| is non-NULL or |md| has changed, initialize with a new key
110    * rather than rewinding the previous one.
111    *
112    * TODO(davidben,eroman): Passing the previous |md| with a NULL |key| is
113    * ambiguous between using the empty key and reusing the previous key. There
114    * exist callers which intend the latter, but the former is an awkward edge
115    * case. Fix to API to avoid this. */
116   if (md != ctx->md || key != NULL) {
117     size_t i;
118     uint8_t pad[HMAC_MAX_MD_CBLOCK];
119     uint8_t key_block[HMAC_MAX_MD_CBLOCK];
120     unsigned key_block_len;
121 
122     size_t block_size = EVP_MD_block_size(md);
123     assert(block_size <= sizeof(key_block));
124     if (block_size < key_len) {
125       /* Long keys are hashed. */
126       if (!EVP_DigestInit_ex(&ctx->md_ctx, md, impl) ||
127           !EVP_DigestUpdate(&ctx->md_ctx, key, key_len) ||
128           !EVP_DigestFinal_ex(&ctx->md_ctx, key_block, &key_block_len)) {
129         return 0;
130       }
131     } else {
132       assert(key_len <= sizeof(key_block));
133       memcpy(key_block, key, key_len);
134       key_block_len = (unsigned)key_len;
135     }
136     /* Keys are then padded with zeros. */
137     if (key_block_len != HMAC_MAX_MD_CBLOCK) {
138       memset(&key_block[key_block_len], 0, sizeof(key_block) - key_block_len);
139     }
140 
141     for (i = 0; i < HMAC_MAX_MD_CBLOCK; i++) {
142       pad[i] = 0x36 ^ key_block[i];
143     }
144     if (!EVP_DigestInit_ex(&ctx->i_ctx, md, impl) ||
145         !EVP_DigestUpdate(&ctx->i_ctx, pad, EVP_MD_block_size(md))) {
146       return 0;
147     }
148 
149     for (i = 0; i < HMAC_MAX_MD_CBLOCK; i++) {
150       pad[i] = 0x5c ^ key_block[i];
151     }
152     if (!EVP_DigestInit_ex(&ctx->o_ctx, md, impl) ||
153         !EVP_DigestUpdate(&ctx->o_ctx, pad, EVP_MD_block_size(md))) {
154       return 0;
155     }
156 
157     ctx->md = md;
158   }
159 
160   if (!EVP_MD_CTX_copy_ex(&ctx->md_ctx, &ctx->i_ctx)) {
161     return 0;
162   }
163 
164   return 1;
165 }
166 
HMAC_Update(HMAC_CTX * ctx,const uint8_t * data,size_t data_len)167 int HMAC_Update(HMAC_CTX *ctx, const uint8_t *data, size_t data_len) {
168   return EVP_DigestUpdate(&ctx->md_ctx, data, data_len);
169 }
170 
HMAC_Final(HMAC_CTX * ctx,uint8_t * out,unsigned int * out_len)171 int HMAC_Final(HMAC_CTX *ctx, uint8_t *out, unsigned int *out_len) {
172   unsigned int i;
173   uint8_t buf[EVP_MAX_MD_SIZE];
174 
175   /* TODO(davidben): The only thing that can officially fail here is
176    * |EVP_MD_CTX_copy_ex|, but even that should be impossible in this case. */
177   if (!EVP_DigestFinal_ex(&ctx->md_ctx, buf, &i) ||
178       !EVP_MD_CTX_copy_ex(&ctx->md_ctx, &ctx->o_ctx) ||
179       !EVP_DigestUpdate(&ctx->md_ctx, buf, i) ||
180       !EVP_DigestFinal_ex(&ctx->md_ctx, out, out_len)) {
181     *out_len = 0;
182     return 0;
183   }
184 
185   return 1;
186 }
187 
HMAC_size(const HMAC_CTX * ctx)188 size_t HMAC_size(const HMAC_CTX *ctx) {
189   return EVP_MD_size(ctx->md);
190 }
191 
HMAC_CTX_copy_ex(HMAC_CTX * dest,const HMAC_CTX * src)192 int HMAC_CTX_copy_ex(HMAC_CTX *dest, const HMAC_CTX *src) {
193   if (!EVP_MD_CTX_copy_ex(&dest->i_ctx, &src->i_ctx) ||
194       !EVP_MD_CTX_copy_ex(&dest->o_ctx, &src->o_ctx) ||
195       !EVP_MD_CTX_copy_ex(&dest->md_ctx, &src->md_ctx)) {
196     return 0;
197   }
198 
199   dest->md = src->md;
200   return 1;
201 }
202 
HMAC_Init(HMAC_CTX * ctx,const void * key,int key_len,const EVP_MD * md)203 int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len, const EVP_MD *md) {
204   if (key && md) {
205     HMAC_CTX_init(ctx);
206   }
207   return HMAC_Init_ex(ctx, key, key_len, md, NULL);
208 }
209 
HMAC_CTX_copy(HMAC_CTX * dest,const HMAC_CTX * src)210 int HMAC_CTX_copy(HMAC_CTX *dest, const HMAC_CTX *src) {
211   HMAC_CTX_init(dest);
212   return HMAC_CTX_copy_ex(dest, src);
213 }
214