1 /* Copyright (c) 2017, Google Inc.
2 *
3 * Permission to use, copy, modify, and/or distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14
15 #include <openssl/aead.h>
16 #include <openssl/cipher.h>
17 #include <openssl/crypto.h>
18 #include <openssl/err.h>
19 #include <openssl/sha.h>
20
21 #include "../fipsmodule/cipher/internal.h"
22
23
24 #define EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN SHA256_DIGEST_LENGTH
25 #define EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN 12
26
27 struct aead_aes_ctr_hmac_sha256_ctx {
28 union {
29 double align;
30 AES_KEY ks;
31 } ks;
32 ctr128_f ctr;
33 block128_f block;
34 SHA256_CTX inner_init_state;
35 SHA256_CTX outer_init_state;
36 };
37
hmac_init(SHA256_CTX * out_inner,SHA256_CTX * out_outer,const uint8_t hmac_key[32])38 static void hmac_init(SHA256_CTX *out_inner, SHA256_CTX *out_outer,
39 const uint8_t hmac_key[32]) {
40 static const size_t hmac_key_len = 32;
41 uint8_t block[SHA256_CBLOCK];
42 OPENSSL_memcpy(block, hmac_key, hmac_key_len);
43 OPENSSL_memset(block + hmac_key_len, 0x36, sizeof(block) - hmac_key_len);
44
45 unsigned i;
46 for (i = 0; i < hmac_key_len; i++) {
47 block[i] ^= 0x36;
48 }
49
50 SHA256_Init(out_inner);
51 SHA256_Update(out_inner, block, sizeof(block));
52
53 OPENSSL_memset(block + hmac_key_len, 0x5c, sizeof(block) - hmac_key_len);
54 for (i = 0; i < hmac_key_len; i++) {
55 block[i] ^= (0x36 ^ 0x5c);
56 }
57
58 SHA256_Init(out_outer);
59 SHA256_Update(out_outer, block, sizeof(block));
60 }
61
aead_aes_ctr_hmac_sha256_init(EVP_AEAD_CTX * ctx,const uint8_t * key,size_t key_len,size_t tag_len)62 static int aead_aes_ctr_hmac_sha256_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
63 size_t key_len, size_t tag_len) {
64 struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx;
65 static const size_t hmac_key_len = 32;
66
67 if (key_len < hmac_key_len) {
68 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH);
69 return 0; /* EVP_AEAD_CTX_init should catch this. */
70 }
71
72 const size_t aes_key_len = key_len - hmac_key_len;
73 if (aes_key_len != 16 && aes_key_len != 32) {
74 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH);
75 return 0; /* EVP_AEAD_CTX_init should catch this. */
76 }
77
78 if (tag_len == EVP_AEAD_DEFAULT_TAG_LENGTH) {
79 tag_len = EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN;
80 }
81
82 if (tag_len > EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN) {
83 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE);
84 return 0;
85 }
86
87 aes_ctx = OPENSSL_malloc(sizeof(struct aead_aes_ctr_hmac_sha256_ctx));
88 if (aes_ctx == NULL) {
89 OPENSSL_PUT_ERROR(CIPHER, ERR_R_MALLOC_FAILURE);
90 return 0;
91 }
92
93 aes_ctx->ctr =
94 aes_ctr_set_key(&aes_ctx->ks.ks, NULL, &aes_ctx->block, key, aes_key_len);
95 ctx->tag_len = tag_len;
96 hmac_init(&aes_ctx->inner_init_state, &aes_ctx->outer_init_state,
97 key + aes_key_len);
98
99 ctx->aead_state = aes_ctx;
100
101 return 1;
102 }
103
aead_aes_ctr_hmac_sha256_cleanup(EVP_AEAD_CTX * ctx)104 static void aead_aes_ctr_hmac_sha256_cleanup(EVP_AEAD_CTX *ctx) {
105 struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx = ctx->aead_state;
106 OPENSSL_cleanse(aes_ctx, sizeof(struct aead_aes_ctr_hmac_sha256_ctx));
107 OPENSSL_free(aes_ctx);
108 }
109
hmac_update_uint64(SHA256_CTX * sha256,uint64_t value)110 static void hmac_update_uint64(SHA256_CTX *sha256, uint64_t value) {
111 unsigned i;
112 uint8_t bytes[8];
113
114 for (i = 0; i < sizeof(bytes); i++) {
115 bytes[i] = value & 0xff;
116 value >>= 8;
117 }
118 SHA256_Update(sha256, bytes, sizeof(bytes));
119 }
120
hmac_calculate(uint8_t out[SHA256_DIGEST_LENGTH],const SHA256_CTX * inner_init_state,const SHA256_CTX * outer_init_state,const uint8_t * ad,size_t ad_len,const uint8_t * nonce,const uint8_t * ciphertext,size_t ciphertext_len)121 static void hmac_calculate(uint8_t out[SHA256_DIGEST_LENGTH],
122 const SHA256_CTX *inner_init_state,
123 const SHA256_CTX *outer_init_state,
124 const uint8_t *ad, size_t ad_len,
125 const uint8_t *nonce, const uint8_t *ciphertext,
126 size_t ciphertext_len) {
127 SHA256_CTX sha256;
128 OPENSSL_memcpy(&sha256, inner_init_state, sizeof(sha256));
129 hmac_update_uint64(&sha256, ad_len);
130 hmac_update_uint64(&sha256, ciphertext_len);
131 SHA256_Update(&sha256, nonce, EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN);
132 SHA256_Update(&sha256, ad, ad_len);
133
134 /* Pad with zeros to the end of the SHA-256 block. */
135 const unsigned num_padding =
136 (SHA256_CBLOCK - ((sizeof(uint64_t)*2 +
137 EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN + ad_len) %
138 SHA256_CBLOCK)) %
139 SHA256_CBLOCK;
140 uint8_t padding[SHA256_CBLOCK];
141 OPENSSL_memset(padding, 0, num_padding);
142 SHA256_Update(&sha256, padding, num_padding);
143
144 SHA256_Update(&sha256, ciphertext, ciphertext_len);
145
146 uint8_t inner_digest[SHA256_DIGEST_LENGTH];
147 SHA256_Final(inner_digest, &sha256);
148
149 OPENSSL_memcpy(&sha256, outer_init_state, sizeof(sha256));
150 SHA256_Update(&sha256, inner_digest, sizeof(inner_digest));
151 SHA256_Final(out, &sha256);
152 }
153
aead_aes_ctr_hmac_sha256_crypt(const struct aead_aes_ctr_hmac_sha256_ctx * aes_ctx,uint8_t * out,const uint8_t * in,size_t len,const uint8_t * nonce)154 static void aead_aes_ctr_hmac_sha256_crypt(
155 const struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx, uint8_t *out,
156 const uint8_t *in, size_t len, const uint8_t *nonce) {
157 /* Since the AEAD operation is one-shot, keeping a buffer of unused keystream
158 * bytes is pointless. However, |CRYPTO_ctr128_encrypt| requires it. */
159 uint8_t partial_block_buffer[AES_BLOCK_SIZE];
160 unsigned partial_block_offset = 0;
161 OPENSSL_memset(partial_block_buffer, 0, sizeof(partial_block_buffer));
162
163 uint8_t counter[AES_BLOCK_SIZE];
164 OPENSSL_memcpy(counter, nonce, EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN);
165 OPENSSL_memset(counter + EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN, 0, 4);
166
167 if (aes_ctx->ctr) {
168 CRYPTO_ctr128_encrypt_ctr32(in, out, len, &aes_ctx->ks.ks, counter,
169 partial_block_buffer, &partial_block_offset,
170 aes_ctx->ctr);
171 } else {
172 CRYPTO_ctr128_encrypt(in, out, len, &aes_ctx->ks.ks, counter,
173 partial_block_buffer, &partial_block_offset,
174 aes_ctx->block);
175 }
176 }
177
aead_aes_ctr_hmac_sha256_seal_scatter(const EVP_AEAD_CTX * ctx,uint8_t * out,uint8_t * out_tag,size_t * out_tag_len,size_t max_out_tag_len,const uint8_t * nonce,size_t nonce_len,const uint8_t * in,size_t in_len,const uint8_t * extra_in,size_t extra_in_len,const uint8_t * ad,size_t ad_len)178 static int aead_aes_ctr_hmac_sha256_seal_scatter(
179 const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag,
180 size_t *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce,
181 size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in,
182 size_t extra_in_len, const uint8_t *ad, size_t ad_len) {
183 const struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx = ctx->aead_state;
184 const uint64_t in_len_64 = in_len;
185
186 if (in_len_64 >= (UINT64_C(1) << 32) * AES_BLOCK_SIZE) {
187 /* This input is so large it would overflow the 32-bit block counter. */
188 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
189 return 0;
190 }
191
192 if (max_out_tag_len < ctx->tag_len) {
193 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
194 return 0;
195 }
196
197 if (nonce_len != EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN) {
198 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
199 return 0;
200 }
201
202 aead_aes_ctr_hmac_sha256_crypt(aes_ctx, out, in, in_len, nonce);
203
204 uint8_t hmac_result[SHA256_DIGEST_LENGTH];
205 hmac_calculate(hmac_result, &aes_ctx->inner_init_state,
206 &aes_ctx->outer_init_state, ad, ad_len, nonce, out, in_len);
207 OPENSSL_memcpy(out_tag, hmac_result, ctx->tag_len);
208 *out_tag_len = ctx->tag_len;
209
210 return 1;
211 }
212
aead_aes_ctr_hmac_sha256_open_gather(const EVP_AEAD_CTX * ctx,uint8_t * out,const uint8_t * nonce,size_t nonce_len,const uint8_t * in,size_t in_len,const uint8_t * in_tag,size_t in_tag_len,const uint8_t * ad,size_t ad_len)213 static int aead_aes_ctr_hmac_sha256_open_gather(
214 const EVP_AEAD_CTX *ctx, uint8_t *out, const uint8_t *nonce,
215 size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *in_tag,
216 size_t in_tag_len, const uint8_t *ad, size_t ad_len) {
217 const struct aead_aes_ctr_hmac_sha256_ctx *aes_ctx = ctx->aead_state;
218
219 if (in_tag_len != ctx->tag_len) {
220 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
221 return 0;
222 }
223
224 if (nonce_len != EVP_AEAD_AES_CTR_HMAC_SHA256_NONCE_LEN) {
225 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
226 return 0;
227 }
228
229 uint8_t hmac_result[SHA256_DIGEST_LENGTH];
230 hmac_calculate(hmac_result, &aes_ctx->inner_init_state,
231 &aes_ctx->outer_init_state, ad, ad_len, nonce, in,
232 in_len);
233 if (CRYPTO_memcmp(hmac_result, in_tag, ctx->tag_len) != 0) {
234 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
235 return 0;
236 }
237
238 aead_aes_ctr_hmac_sha256_crypt(aes_ctx, out, in, in_len, nonce);
239
240 return 1;
241 }
242
243 static const EVP_AEAD aead_aes_128_ctr_hmac_sha256 = {
244 16 /* AES key */ + 32 /* HMAC key */,
245 12, /* nonce length */
246 EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, /* overhead */
247 EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, /* max tag length */
248 0, /* seal_scatter_supports_extra_in */
249
250 aead_aes_ctr_hmac_sha256_init,
251 NULL /* init_with_direction */,
252 aead_aes_ctr_hmac_sha256_cleanup,
253 NULL /* open */,
254 aead_aes_ctr_hmac_sha256_seal_scatter,
255 aead_aes_ctr_hmac_sha256_open_gather,
256 NULL /* get_iv */,
257 };
258
259 static const EVP_AEAD aead_aes_256_ctr_hmac_sha256 = {
260 32 /* AES key */ + 32 /* HMAC key */,
261 12, /* nonce length */
262 EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, /* overhead */
263 EVP_AEAD_AES_CTR_HMAC_SHA256_TAG_LEN, /* max tag length */
264 0, /* seal_scatter_supports_extra_in */
265
266 aead_aes_ctr_hmac_sha256_init,
267 NULL /* init_with_direction */,
268 aead_aes_ctr_hmac_sha256_cleanup,
269 NULL /* open */,
270 aead_aes_ctr_hmac_sha256_seal_scatter,
271 aead_aes_ctr_hmac_sha256_open_gather,
272 NULL /* get_iv */,
273 };
274
EVP_aead_aes_128_ctr_hmac_sha256(void)275 const EVP_AEAD *EVP_aead_aes_128_ctr_hmac_sha256(void) {
276 return &aead_aes_128_ctr_hmac_sha256;
277 }
278
EVP_aead_aes_256_ctr_hmac_sha256(void)279 const EVP_AEAD *EVP_aead_aes_256_ctr_hmac_sha256(void) {
280 return &aead_aes_256_ctr_hmac_sha256;
281 }
282