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
17 #include <assert.h>
18
19 #include <openssl/cipher.h>
20 #include <openssl/cpu.h>
21 #include <openssl/crypto.h>
22 #include <openssl/err.h>
23
24 #include "../fipsmodule/cipher/internal.h"
25
26
27 #define EVP_AEAD_AES_GCM_SIV_NONCE_LEN 12
28 #define EVP_AEAD_AES_GCM_SIV_TAG_LEN 16
29
30 #if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM)
31
32 // Optimised AES-GCM-SIV
33
34 struct aead_aes_gcm_siv_asm_ctx {
35 alignas(16) uint8_t key[16*15];
36 int is_128_bit;
37 // ptr contains the original pointer from |OPENSSL_malloc|, which may only be
38 // 8-byte aligned. When freeing this structure, actually call |OPENSSL_free|
39 // on this pointer.
40 void *ptr;
41 };
42
43 // aes128gcmsiv_aes_ks writes an AES-128 key schedule for |key| to
44 // |out_expanded_key|.
45 extern void aes128gcmsiv_aes_ks(
46 const uint8_t key[16], uint8_t out_expanded_key[16*15]);
47
48 // aes128gcmsiv_aes_ks writes an AES-128 key schedule for |key| to
49 // |out_expanded_key|.
50 extern void aes256gcmsiv_aes_ks(
51 const uint8_t key[16], uint8_t out_expanded_key[16*15]);
52
aead_aes_gcm_siv_asm_init(EVP_AEAD_CTX * ctx,const uint8_t * key,size_t key_len,size_t tag_len)53 static int aead_aes_gcm_siv_asm_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
54 size_t key_len, size_t tag_len) {
55 const size_t key_bits = key_len * 8;
56
57 if (key_bits != 128 && key_bits != 256) {
58 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH);
59 return 0; // EVP_AEAD_CTX_init should catch this.
60 }
61
62 if (tag_len == EVP_AEAD_DEFAULT_TAG_LENGTH) {
63 tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN;
64 }
65
66 if (tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN) {
67 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE);
68 return 0;
69 }
70
71 char *ptr = OPENSSL_malloc(sizeof(struct aead_aes_gcm_siv_asm_ctx) + 8);
72 if (ptr == NULL) {
73 return 0;
74 }
75 assert((((uintptr_t)ptr) & 7) == 0);
76
77 // gcm_siv_ctx needs to be 16-byte aligned in a cross-platform way.
78 struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx =
79 (struct aead_aes_gcm_siv_asm_ctx *)(ptr + (((uintptr_t)ptr) & 8));
80
81 assert((((uintptr_t)gcm_siv_ctx) & 15) == 0);
82 gcm_siv_ctx->ptr = ptr;
83
84 if (key_bits == 128) {
85 aes128gcmsiv_aes_ks(key, &gcm_siv_ctx->key[0]);
86 gcm_siv_ctx->is_128_bit = 1;
87 } else {
88 aes256gcmsiv_aes_ks(key, &gcm_siv_ctx->key[0]);
89 gcm_siv_ctx->is_128_bit = 0;
90 }
91 ctx->aead_state = gcm_siv_ctx;
92 ctx->tag_len = tag_len;
93
94 return 1;
95 }
96
aead_aes_gcm_siv_asm_cleanup(EVP_AEAD_CTX * ctx)97 static void aead_aes_gcm_siv_asm_cleanup(EVP_AEAD_CTX *ctx) {
98 const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = ctx->aead_state;
99 OPENSSL_free(gcm_siv_ctx->ptr);
100 }
101
102 // aesgcmsiv_polyval_horner updates the POLYVAL value in |in_out_poly| to
103 // include a number (|in_blocks|) of 16-byte blocks of data from |in|, given
104 // the POLYVAL key in |key|.
105 extern void aesgcmsiv_polyval_horner(const uint8_t in_out_poly[16],
106 const uint8_t key[16], const uint8_t *in,
107 size_t in_blocks);
108
109 // aesgcmsiv_htable_init writes powers 1..8 of |auth_key| to |out_htable|.
110 extern void aesgcmsiv_htable_init(uint8_t out_htable[16 * 8],
111 const uint8_t auth_key[16]);
112
113 // aesgcmsiv_htable6_init writes powers 1..6 of |auth_key| to |out_htable|.
114 extern void aesgcmsiv_htable6_init(uint8_t out_htable[16 * 6],
115 const uint8_t auth_key[16]);
116
117 // aesgcmsiv_htable_polyval updates the POLYVAL value in |in_out_poly| to
118 // include |in_len| bytes of data from |in|. (Where |in_len| must be a multiple
119 // of 16.) It uses the precomputed powers of the key given in |htable|.
120 extern void aesgcmsiv_htable_polyval(const uint8_t htable[16 * 8],
121 const uint8_t *in, size_t in_len,
122 uint8_t in_out_poly[16]);
123
124 // aes128gcmsiv_dec decrypts |in_len| & ~15 bytes from |out| and writes them to
125 // |in|. (The full value of |in_len| is still used to find the authentication
126 // tag appended to the ciphertext, however, so must not be pre-masked.)
127 //
128 // |in| and |out| may be equal, but must not otherwise overlap.
129 //
130 // While decrypting, it updates the POLYVAL value found at the beginning of
131 // |in_out_calculated_tag_and_scratch| and writes the updated value back before
132 // return. During executation, it may use the whole of this space for other
133 // purposes. In order to decrypt and update the POLYVAL value, it uses the
134 // expanded key from |key| and the table of powers in |htable|.
135 extern void aes128gcmsiv_dec(const uint8_t *in, uint8_t *out,
136 uint8_t in_out_calculated_tag_and_scratch[16 * 8],
137 const uint8_t htable[16 * 6],
138 const struct aead_aes_gcm_siv_asm_ctx *key,
139 size_t in_len);
140
141 // aes256gcmsiv_dec acts like |aes128gcmsiv_dec|, but for AES-256.
142 extern void aes256gcmsiv_dec(const uint8_t *in, uint8_t *out,
143 uint8_t in_out_calculated_tag_and_scratch[16 * 8],
144 const uint8_t htable[16 * 6],
145 const struct aead_aes_gcm_siv_asm_ctx *key,
146 size_t in_len);
147
148 // aes128gcmsiv_kdf performs the AES-GCM-SIV KDF given the expanded key from
149 // |key_schedule| and the nonce in |nonce|. Note that, while only 12 bytes of
150 // the nonce are used, 16 bytes are read and so the value must be
151 // right-padded.
152 extern void aes128gcmsiv_kdf(const uint8_t nonce[16],
153 uint64_t out_key_material[8],
154 const uint8_t *key_schedule);
155
156 // aes256gcmsiv_kdf acts like |aes128gcmsiv_kdf|, but for AES-256.
157 extern void aes256gcmsiv_kdf(const uint8_t nonce[16],
158 uint64_t out_key_material[12],
159 const uint8_t *key_schedule);
160
161 // aes128gcmsiv_aes_ks_enc_x1 performs a key expansion of the AES-128 key in
162 // |key|, writes the expanded key to |out_expanded_key| and encrypts a single
163 // block from |in| to |out|.
164 extern void aes128gcmsiv_aes_ks_enc_x1(const uint8_t in[16], uint8_t out[16],
165 uint8_t out_expanded_key[16 * 15],
166 const uint64_t key[2]);
167
168 // aes256gcmsiv_aes_ks_enc_x1 acts like |aes128gcmsiv_aes_ks_enc_x1|, but for
169 // AES-256.
170 extern void aes256gcmsiv_aes_ks_enc_x1(const uint8_t in[16], uint8_t out[16],
171 uint8_t out_expanded_key[16 * 15],
172 const uint64_t key[4]);
173
174 // aes128gcmsiv_ecb_enc_block encrypts a single block from |in| to |out| using
175 // the expanded key in |expanded_key|.
176 extern void aes128gcmsiv_ecb_enc_block(
177 const uint8_t in[16], uint8_t out[16],
178 const struct aead_aes_gcm_siv_asm_ctx *expanded_key);
179
180 // aes256gcmsiv_ecb_enc_block acts like |aes128gcmsiv_ecb_enc_block|, but for
181 // AES-256.
182 extern void aes256gcmsiv_ecb_enc_block(
183 const uint8_t in[16], uint8_t out[16],
184 const struct aead_aes_gcm_siv_asm_ctx *expanded_key);
185
186 // aes128gcmsiv_enc_msg_x4 encrypts |in_len| bytes from |in| to |out| using the
187 // expanded key from |key|. (The value of |in_len| must be a multiple of 16.)
188 // The |in| and |out| buffers may be equal but must not otherwise overlap. The
189 // initial counter is constructed from the given |tag| as required by
190 // AES-GCM-SIV.
191 extern void aes128gcmsiv_enc_msg_x4(const uint8_t *in, uint8_t *out,
192 const uint8_t *tag,
193 const struct aead_aes_gcm_siv_asm_ctx *key,
194 size_t in_len);
195
196 // aes256gcmsiv_enc_msg_x4 acts like |aes128gcmsiv_enc_msg_x4|, but for
197 // AES-256.
198 extern void aes256gcmsiv_enc_msg_x4(const uint8_t *in, uint8_t *out,
199 const uint8_t *tag,
200 const struct aead_aes_gcm_siv_asm_ctx *key,
201 size_t in_len);
202
203 // aes128gcmsiv_enc_msg_x8 acts like |aes128gcmsiv_enc_msg_x4|, but is
204 // optimised for longer messages.
205 extern void aes128gcmsiv_enc_msg_x8(const uint8_t *in, uint8_t *out,
206 const uint8_t *tag,
207 const struct aead_aes_gcm_siv_asm_ctx *key,
208 size_t in_len);
209
210 // aes256gcmsiv_enc_msg_x8 acts like |aes256gcmsiv_enc_msg_x4|, but is
211 // optimised for longer messages.
212 extern void aes256gcmsiv_enc_msg_x8(const uint8_t *in, uint8_t *out,
213 const uint8_t *tag,
214 const struct aead_aes_gcm_siv_asm_ctx *key,
215 size_t in_len);
216
217 // gcm_siv_asm_polyval evaluates POLYVAL at |auth_key| on the given plaintext
218 // and AD. The result is written to |out_tag|.
gcm_siv_asm_polyval(uint8_t out_tag[16],const uint8_t * in,size_t in_len,const uint8_t * ad,size_t ad_len,const uint8_t auth_key[16],const uint8_t nonce[12])219 static void gcm_siv_asm_polyval(uint8_t out_tag[16], const uint8_t *in,
220 size_t in_len, const uint8_t *ad, size_t ad_len,
221 const uint8_t auth_key[16],
222 const uint8_t nonce[12]) {
223 OPENSSL_memset(out_tag, 0, 16);
224 const size_t ad_blocks = ad_len / 16;
225 const size_t in_blocks = in_len / 16;
226 int htable_init = 0;
227 alignas(16) uint8_t htable[16*8];
228
229 if (ad_blocks > 8 || in_blocks > 8) {
230 htable_init = 1;
231 aesgcmsiv_htable_init(htable, auth_key);
232 }
233
234 if (htable_init) {
235 aesgcmsiv_htable_polyval(htable, ad, ad_len & ~15, out_tag);
236 } else {
237 aesgcmsiv_polyval_horner(out_tag, auth_key, ad, ad_blocks);
238 }
239
240 uint8_t scratch[16];
241 if (ad_len & 15) {
242 OPENSSL_memset(scratch, 0, sizeof(scratch));
243 OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15);
244 aesgcmsiv_polyval_horner(out_tag, auth_key, scratch, 1);
245 }
246
247 if (htable_init) {
248 aesgcmsiv_htable_polyval(htable, in, in_len & ~15, out_tag);
249 } else {
250 aesgcmsiv_polyval_horner(out_tag, auth_key, in, in_blocks);
251 }
252
253 if (in_len & 15) {
254 OPENSSL_memset(scratch, 0, sizeof(scratch));
255 OPENSSL_memcpy(scratch, &in[in_len & ~15], in_len & 15);
256 aesgcmsiv_polyval_horner(out_tag, auth_key, scratch, 1);
257 }
258
259 union {
260 uint8_t c[16];
261 struct {
262 uint64_t ad;
263 uint64_t in;
264 } bitlens;
265 } length_block;
266
267 length_block.bitlens.ad = ad_len * 8;
268 length_block.bitlens.in = in_len * 8;
269 aesgcmsiv_polyval_horner(out_tag, auth_key, length_block.c, 1);
270
271 for (size_t i = 0; i < 12; i++) {
272 out_tag[i] ^= nonce[i];
273 }
274
275 out_tag[15] &= 0x7f;
276 }
277
278 // aead_aes_gcm_siv_asm_crypt_last_block handles the encryption/decryption
279 // (same thing in CTR mode) of the final block of a plaintext/ciphertext. It
280 // writes |in_len| & 15 bytes to |out| + |in_len|, based on an initial counter
281 // derived from |tag|.
aead_aes_gcm_siv_asm_crypt_last_block(int is_128_bit,uint8_t * out,const uint8_t * in,size_t in_len,const uint8_t tag[16],const struct aead_aes_gcm_siv_asm_ctx * enc_key_expanded)282 static void aead_aes_gcm_siv_asm_crypt_last_block(
283 int is_128_bit, uint8_t *out, const uint8_t *in, size_t in_len,
284 const uint8_t tag[16],
285 const struct aead_aes_gcm_siv_asm_ctx *enc_key_expanded) {
286 alignas(16) union {
287 uint8_t c[16];
288 uint32_t u32[4];
289 } counter;
290 OPENSSL_memcpy(&counter, tag, sizeof(counter));
291 counter.c[15] |= 0x80;
292 counter.u32[0] += in_len / 16;
293
294 if (is_128_bit) {
295 aes128gcmsiv_ecb_enc_block(&counter.c[0], &counter.c[0], enc_key_expanded);
296 } else {
297 aes256gcmsiv_ecb_enc_block(&counter.c[0], &counter.c[0], enc_key_expanded);
298 }
299
300 const size_t last_bytes_offset = in_len & ~15;
301 const size_t last_bytes_len = in_len & 15;
302 uint8_t *last_bytes_out = &out[last_bytes_offset];
303 const uint8_t *last_bytes_in = &in[last_bytes_offset];
304 for (size_t i = 0; i < last_bytes_len; i++) {
305 last_bytes_out[i] = last_bytes_in[i] ^ counter.c[i];
306 }
307 }
308
309 // aead_aes_gcm_siv_kdf calculates the record encryption and authentication
310 // keys given the |nonce|.
aead_aes_gcm_siv_kdf(int is_128_bit,const struct aead_aes_gcm_siv_asm_ctx * gcm_siv_ctx,uint64_t out_record_auth_key[2],uint64_t out_record_enc_key[4],const uint8_t nonce[12])311 static void aead_aes_gcm_siv_kdf(
312 int is_128_bit, const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx,
313 uint64_t out_record_auth_key[2], uint64_t out_record_enc_key[4],
314 const uint8_t nonce[12]) {
315 alignas(16) uint8_t padded_nonce[16];
316 OPENSSL_memcpy(padded_nonce, nonce, 12);
317
318 alignas(16) uint64_t key_material[12];
319 if (is_128_bit) {
320 aes128gcmsiv_kdf(padded_nonce, key_material, &gcm_siv_ctx->key[0]);
321 out_record_enc_key[0] = key_material[4];
322 out_record_enc_key[1] = key_material[6];
323 } else {
324 aes256gcmsiv_kdf(padded_nonce, key_material, &gcm_siv_ctx->key[0]);
325 out_record_enc_key[0] = key_material[4];
326 out_record_enc_key[1] = key_material[6];
327 out_record_enc_key[2] = key_material[8];
328 out_record_enc_key[3] = key_material[10];
329 }
330
331 out_record_auth_key[0] = key_material[0];
332 out_record_auth_key[1] = key_material[2];
333 }
334
aead_aes_gcm_siv_asm_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)335 static int aead_aes_gcm_siv_asm_seal_scatter(
336 const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag,
337 size_t *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce,
338 size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in,
339 size_t extra_in_len, const uint8_t *ad, size_t ad_len) {
340 const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = ctx->aead_state;
341 const uint64_t in_len_64 = in_len;
342 const uint64_t ad_len_64 = ad_len;
343
344 if (in_len_64 > (UINT64_C(1) << 36) ||
345 ad_len_64 >= (UINT64_C(1) << 61)) {
346 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
347 return 0;
348 }
349
350 if (max_out_tag_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN) {
351 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
352 return 0;
353 }
354
355 if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) {
356 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
357 return 0;
358 }
359
360 alignas(16) uint64_t record_auth_key[2];
361 alignas(16) uint64_t record_enc_key[4];
362 aead_aes_gcm_siv_kdf(gcm_siv_ctx->is_128_bit, gcm_siv_ctx, record_auth_key,
363 record_enc_key, nonce);
364
365 alignas(16) uint8_t tag[16] = {0};
366 gcm_siv_asm_polyval(tag, in, in_len, ad, ad_len,
367 (const uint8_t *)record_auth_key, nonce);
368
369 struct aead_aes_gcm_siv_asm_ctx enc_key_expanded;
370
371 if (gcm_siv_ctx->is_128_bit) {
372 aes128gcmsiv_aes_ks_enc_x1(tag, tag, &enc_key_expanded.key[0],
373 record_enc_key);
374
375 if (in_len < 128) {
376 aes128gcmsiv_enc_msg_x4(in, out, tag, &enc_key_expanded, in_len & ~15);
377 } else {
378 aes128gcmsiv_enc_msg_x8(in, out, tag, &enc_key_expanded, in_len & ~15);
379 }
380 } else {
381 aes256gcmsiv_aes_ks_enc_x1(tag, tag, &enc_key_expanded.key[0],
382 record_enc_key);
383
384 if (in_len < 128) {
385 aes256gcmsiv_enc_msg_x4(in, out, tag, &enc_key_expanded, in_len & ~15);
386 } else {
387 aes256gcmsiv_enc_msg_x8(in, out, tag, &enc_key_expanded, in_len & ~15);
388 }
389 }
390
391 if (in_len & 15) {
392 aead_aes_gcm_siv_asm_crypt_last_block(gcm_siv_ctx->is_128_bit, out, in,
393 in_len, tag, &enc_key_expanded);
394 }
395
396 OPENSSL_memcpy(out_tag, tag, sizeof(tag));
397 *out_tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN;
398
399 return 1;
400 }
401
402 // TODO(martinkr): Add aead_aes_gcm_siv_asm_open_gather. N.B. aes128gcmsiv_dec
403 // expects ciphertext and tag in a contiguous buffer.
404
aead_aes_gcm_siv_asm_open(const EVP_AEAD_CTX * ctx,uint8_t * out,size_t * out_len,size_t max_out_len,const uint8_t * nonce,size_t nonce_len,const uint8_t * in,size_t in_len,const uint8_t * ad,size_t ad_len)405 static int aead_aes_gcm_siv_asm_open(const EVP_AEAD_CTX *ctx, uint8_t *out,
406 size_t *out_len, size_t max_out_len,
407 const uint8_t *nonce, size_t nonce_len,
408 const uint8_t *in, size_t in_len,
409 const uint8_t *ad, size_t ad_len) {
410 const uint64_t ad_len_64 = ad_len;
411 if (ad_len_64 >= (UINT64_C(1) << 61)) {
412 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
413 return 0;
414 }
415
416 const uint64_t in_len_64 = in_len;
417 if (in_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN ||
418 in_len_64 > (UINT64_C(1) << 36) + AES_BLOCK_SIZE) {
419 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
420 return 0;
421 }
422
423 const struct aead_aes_gcm_siv_asm_ctx *gcm_siv_ctx = ctx->aead_state;
424 const size_t plaintext_len = in_len - EVP_AEAD_AES_GCM_SIV_TAG_LEN;
425 const uint8_t *const given_tag = in + plaintext_len;
426
427 if (max_out_len < plaintext_len) {
428 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
429 return 0;
430 }
431
432 alignas(16) uint64_t record_auth_key[2];
433 alignas(16) uint64_t record_enc_key[4];
434 aead_aes_gcm_siv_kdf(gcm_siv_ctx->is_128_bit, gcm_siv_ctx, record_auth_key,
435 record_enc_key, nonce);
436
437 struct aead_aes_gcm_siv_asm_ctx expanded_key;
438 if (gcm_siv_ctx->is_128_bit) {
439 aes128gcmsiv_aes_ks((const uint8_t *) record_enc_key, &expanded_key.key[0]);
440 } else {
441 aes256gcmsiv_aes_ks((const uint8_t *) record_enc_key, &expanded_key.key[0]);
442 }
443 // calculated_tag is 16*8 bytes, rather than 16 bytes, because
444 // aes[128|256]gcmsiv_dec uses the extra as scratch space.
445 alignas(16) uint8_t calculated_tag[16 * 8] = {0};
446
447 OPENSSL_memset(calculated_tag, 0, EVP_AEAD_AES_GCM_SIV_TAG_LEN);
448 const size_t ad_blocks = ad_len / 16;
449 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key, ad,
450 ad_blocks);
451
452 uint8_t scratch[16];
453 if (ad_len & 15) {
454 OPENSSL_memset(scratch, 0, sizeof(scratch));
455 OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15);
456 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key,
457 scratch, 1);
458 }
459
460 alignas(16) uint8_t htable[16 * 6];
461 aesgcmsiv_htable6_init(htable, (const uint8_t *)record_auth_key);
462
463 if (gcm_siv_ctx->is_128_bit) {
464 aes128gcmsiv_dec(in, out, calculated_tag, htable, &expanded_key,
465 plaintext_len);
466 } else {
467 aes256gcmsiv_dec(in, out, calculated_tag, htable, &expanded_key,
468 plaintext_len);
469 }
470
471 if (plaintext_len & 15) {
472 aead_aes_gcm_siv_asm_crypt_last_block(gcm_siv_ctx->is_128_bit, out, in,
473 plaintext_len, given_tag,
474 &expanded_key);
475 OPENSSL_memset(scratch, 0, sizeof(scratch));
476 OPENSSL_memcpy(scratch, out + (plaintext_len & ~15), plaintext_len & 15);
477 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key,
478 scratch, 1);
479 }
480
481 union {
482 uint8_t c[16];
483 struct {
484 uint64_t ad;
485 uint64_t in;
486 } bitlens;
487 } length_block;
488
489 length_block.bitlens.ad = ad_len * 8;
490 length_block.bitlens.in = plaintext_len * 8;
491 aesgcmsiv_polyval_horner(calculated_tag, (const uint8_t *)record_auth_key,
492 length_block.c, 1);
493
494 for (size_t i = 0; i < 12; i++) {
495 calculated_tag[i] ^= nonce[i];
496 }
497
498 calculated_tag[15] &= 0x7f;
499
500 if (gcm_siv_ctx->is_128_bit) {
501 aes128gcmsiv_ecb_enc_block(calculated_tag, calculated_tag, &expanded_key);
502 } else {
503 aes256gcmsiv_ecb_enc_block(calculated_tag, calculated_tag, &expanded_key);
504 }
505
506 if (CRYPTO_memcmp(calculated_tag, given_tag, EVP_AEAD_AES_GCM_SIV_TAG_LEN) !=
507 0) {
508 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
509 return 0;
510 }
511
512 *out_len = in_len - EVP_AEAD_AES_GCM_SIV_TAG_LEN;
513 return 1;
514 }
515
516 static const EVP_AEAD aead_aes_128_gcm_siv_asm = {
517 16, // key length
518 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length
519 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead
520 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length
521 0, // seal_scatter_supports_extra_in
522
523 aead_aes_gcm_siv_asm_init,
524 NULL /* init_with_direction */,
525 aead_aes_gcm_siv_asm_cleanup,
526 aead_aes_gcm_siv_asm_open,
527 aead_aes_gcm_siv_asm_seal_scatter,
528 NULL /* open_gather */,
529 NULL /* get_iv */,
530 NULL /* tag_len */,
531 };
532
533 static const EVP_AEAD aead_aes_256_gcm_siv_asm = {
534 32, // key length
535 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length
536 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead
537 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length
538 0, // seal_scatter_supports_extra_in
539
540 aead_aes_gcm_siv_asm_init,
541 NULL /* init_with_direction */,
542 aead_aes_gcm_siv_asm_cleanup,
543 aead_aes_gcm_siv_asm_open,
544 aead_aes_gcm_siv_asm_seal_scatter,
545 NULL /* open_gather */,
546 NULL /* get_iv */,
547 NULL /* tag_len */,
548 };
549
550 #endif // X86_64 && !NO_ASM
551
552 struct aead_aes_gcm_siv_ctx {
553 union {
554 double align;
555 AES_KEY ks;
556 } ks;
557 block128_f kgk_block;
558 unsigned is_256:1;
559 };
560
aead_aes_gcm_siv_init(EVP_AEAD_CTX * ctx,const uint8_t * key,size_t key_len,size_t tag_len)561 static int aead_aes_gcm_siv_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
562 size_t key_len, size_t tag_len) {
563 const size_t key_bits = key_len * 8;
564
565 if (key_bits != 128 && key_bits != 256) {
566 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH);
567 return 0; // EVP_AEAD_CTX_init should catch this.
568 }
569
570 if (tag_len == EVP_AEAD_DEFAULT_TAG_LENGTH) {
571 tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN;
572 }
573 if (tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN) {
574 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TAG_TOO_LARGE);
575 return 0;
576 }
577
578 struct aead_aes_gcm_siv_ctx *gcm_siv_ctx =
579 OPENSSL_malloc(sizeof(struct aead_aes_gcm_siv_ctx));
580 if (gcm_siv_ctx == NULL) {
581 return 0;
582 }
583 OPENSSL_memset(gcm_siv_ctx, 0, sizeof(struct aead_aes_gcm_siv_ctx));
584
585 aes_ctr_set_key(&gcm_siv_ctx->ks.ks, NULL, &gcm_siv_ctx->kgk_block, key,
586 key_len);
587 gcm_siv_ctx->is_256 = (key_len == 32);
588 ctx->aead_state = gcm_siv_ctx;
589 ctx->tag_len = tag_len;
590
591 return 1;
592 }
593
aead_aes_gcm_siv_cleanup(EVP_AEAD_CTX * ctx)594 static void aead_aes_gcm_siv_cleanup(EVP_AEAD_CTX *ctx) {
595 OPENSSL_free(ctx->aead_state);
596 }
597
598 // gcm_siv_crypt encrypts (or decrypts—it's the same thing) |in_len| bytes from
599 // |in| to |out|, using the block function |enc_block| with |key| in counter
600 // mode, starting at |initial_counter|. This differs from the traditional
601 // counter mode code in that the counter is handled little-endian, only the
602 // first four bytes are used and the GCM-SIV tweak to the final byte is
603 // applied. The |in| and |out| pointers may be equal but otherwise must not
604 // alias.
gcm_siv_crypt(uint8_t * out,const uint8_t * in,size_t in_len,const uint8_t initial_counter[AES_BLOCK_SIZE],block128_f enc_block,const AES_KEY * key)605 static void gcm_siv_crypt(uint8_t *out, const uint8_t *in, size_t in_len,
606 const uint8_t initial_counter[AES_BLOCK_SIZE],
607 block128_f enc_block, const AES_KEY *key) {
608 union {
609 uint32_t w[4];
610 uint8_t c[16];
611 } counter;
612
613 OPENSSL_memcpy(counter.c, initial_counter, AES_BLOCK_SIZE);
614 counter.c[15] |= 0x80;
615
616 for (size_t done = 0; done < in_len;) {
617 uint8_t keystream[AES_BLOCK_SIZE];
618 enc_block(counter.c, keystream, key);
619 counter.w[0]++;
620
621 size_t todo = AES_BLOCK_SIZE;
622 if (in_len - done < todo) {
623 todo = in_len - done;
624 }
625
626 for (size_t i = 0; i < todo; i++) {
627 out[done + i] = keystream[i] ^ in[done + i];
628 }
629
630 done += todo;
631 }
632 }
633
634 // gcm_siv_polyval evaluates POLYVAL at |auth_key| on the given plaintext and
635 // AD. The result is written to |out_tag|.
gcm_siv_polyval(uint8_t out_tag[16],const uint8_t * in,size_t in_len,const uint8_t * ad,size_t ad_len,const uint8_t auth_key[16],const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN])636 static void gcm_siv_polyval(
637 uint8_t out_tag[16], const uint8_t *in, size_t in_len, const uint8_t *ad,
638 size_t ad_len, const uint8_t auth_key[16],
639 const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN]) {
640 struct polyval_ctx polyval_ctx;
641 CRYPTO_POLYVAL_init(&polyval_ctx, auth_key);
642
643 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, ad, ad_len & ~15);
644
645 uint8_t scratch[16];
646 if (ad_len & 15) {
647 OPENSSL_memset(scratch, 0, sizeof(scratch));
648 OPENSSL_memcpy(scratch, &ad[ad_len & ~15], ad_len & 15);
649 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, scratch, sizeof(scratch));
650 }
651
652 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, in, in_len & ~15);
653 if (in_len & 15) {
654 OPENSSL_memset(scratch, 0, sizeof(scratch));
655 OPENSSL_memcpy(scratch, &in[in_len & ~15], in_len & 15);
656 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, scratch, sizeof(scratch));
657 }
658
659 union {
660 uint8_t c[16];
661 struct {
662 uint64_t ad;
663 uint64_t in;
664 } bitlens;
665 } length_block;
666
667 length_block.bitlens.ad = ad_len * 8;
668 length_block.bitlens.in = in_len * 8;
669 CRYPTO_POLYVAL_update_blocks(&polyval_ctx, length_block.c,
670 sizeof(length_block));
671
672 CRYPTO_POLYVAL_finish(&polyval_ctx, out_tag);
673 for (size_t i = 0; i < EVP_AEAD_AES_GCM_SIV_NONCE_LEN; i++) {
674 out_tag[i] ^= nonce[i];
675 }
676 out_tag[15] &= 0x7f;
677 }
678
679 // gcm_siv_record_keys contains the keys used for a specific GCM-SIV record.
680 struct gcm_siv_record_keys {
681 uint8_t auth_key[16];
682 union {
683 double align;
684 AES_KEY ks;
685 } enc_key;
686 block128_f enc_block;
687 };
688
689 // gcm_siv_keys calculates the keys for a specific GCM-SIV record with the
690 // given nonce and writes them to |*out_keys|.
gcm_siv_keys(const struct aead_aes_gcm_siv_ctx * gcm_siv_ctx,struct gcm_siv_record_keys * out_keys,const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN])691 static void gcm_siv_keys(
692 const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx,
693 struct gcm_siv_record_keys *out_keys,
694 const uint8_t nonce[EVP_AEAD_AES_GCM_SIV_NONCE_LEN]) {
695 const AES_KEY *const key = &gcm_siv_ctx->ks.ks;
696 uint8_t key_material[(128 /* POLYVAL key */ + 256 /* max AES key */) / 8];
697 const size_t blocks_needed = gcm_siv_ctx->is_256 ? 6 : 4;
698
699 uint8_t counter[AES_BLOCK_SIZE];
700 OPENSSL_memset(counter, 0, AES_BLOCK_SIZE - EVP_AEAD_AES_GCM_SIV_NONCE_LEN);
701 OPENSSL_memcpy(counter + AES_BLOCK_SIZE - EVP_AEAD_AES_GCM_SIV_NONCE_LEN,
702 nonce, EVP_AEAD_AES_GCM_SIV_NONCE_LEN);
703 for (size_t i = 0; i < blocks_needed; i++) {
704 counter[0] = i;
705
706 uint8_t ciphertext[AES_BLOCK_SIZE];
707 gcm_siv_ctx->kgk_block(counter, ciphertext, key);
708 OPENSSL_memcpy(&key_material[i * 8], ciphertext, 8);
709 }
710
711 OPENSSL_memcpy(out_keys->auth_key, key_material, 16);
712 aes_ctr_set_key(&out_keys->enc_key.ks, NULL, &out_keys->enc_block,
713 key_material + 16, gcm_siv_ctx->is_256 ? 32 : 16);
714 }
715
aead_aes_gcm_siv_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)716 static int aead_aes_gcm_siv_seal_scatter(
717 const EVP_AEAD_CTX *ctx, uint8_t *out, uint8_t *out_tag,
718 size_t *out_tag_len, size_t max_out_tag_len, const uint8_t *nonce,
719 size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *extra_in,
720 size_t extra_in_len, const uint8_t *ad, size_t ad_len) {
721 const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx = ctx->aead_state;
722 const uint64_t in_len_64 = in_len;
723 const uint64_t ad_len_64 = ad_len;
724
725 if (in_len + EVP_AEAD_AES_GCM_SIV_TAG_LEN < in_len ||
726 in_len_64 > (UINT64_C(1) << 36) ||
727 ad_len_64 >= (UINT64_C(1) << 61)) {
728 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
729 return 0;
730 }
731
732 if (max_out_tag_len < EVP_AEAD_AES_GCM_SIV_TAG_LEN) {
733 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
734 return 0;
735 }
736
737 if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) {
738 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
739 return 0;
740 }
741
742 struct gcm_siv_record_keys keys;
743 gcm_siv_keys(gcm_siv_ctx, &keys, nonce);
744
745 uint8_t tag[16];
746 gcm_siv_polyval(tag, in, in_len, ad, ad_len, keys.auth_key, nonce);
747 keys.enc_block(tag, tag, &keys.enc_key.ks);
748
749 gcm_siv_crypt(out, in, in_len, tag, keys.enc_block, &keys.enc_key.ks);
750
751 OPENSSL_memcpy(out_tag, tag, EVP_AEAD_AES_GCM_SIV_TAG_LEN);
752 *out_tag_len = EVP_AEAD_AES_GCM_SIV_TAG_LEN;
753
754 return 1;
755 }
756
aead_aes_gcm_siv_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)757 static int aead_aes_gcm_siv_open_gather(const EVP_AEAD_CTX *ctx, uint8_t *out,
758 const uint8_t *nonce, size_t nonce_len,
759 const uint8_t *in, size_t in_len,
760 const uint8_t *in_tag,
761 size_t in_tag_len, const uint8_t *ad,
762 size_t ad_len) {
763 const uint64_t ad_len_64 = ad_len;
764 if (ad_len_64 >= (UINT64_C(1) << 61)) {
765 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
766 return 0;
767 }
768
769 const uint64_t in_len_64 = in_len;
770 if (in_tag_len != EVP_AEAD_AES_GCM_SIV_TAG_LEN ||
771 in_len_64 > (UINT64_C(1) << 36) + AES_BLOCK_SIZE) {
772 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
773 return 0;
774 }
775
776 if (nonce_len != EVP_AEAD_AES_GCM_SIV_NONCE_LEN) {
777 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_NONCE_SIZE);
778 return 0;
779 }
780
781 const struct aead_aes_gcm_siv_ctx *gcm_siv_ctx = ctx->aead_state;
782
783 struct gcm_siv_record_keys keys;
784 gcm_siv_keys(gcm_siv_ctx, &keys, nonce);
785
786 gcm_siv_crypt(out, in, in_len, in_tag, keys.enc_block, &keys.enc_key.ks);
787
788 uint8_t expected_tag[EVP_AEAD_AES_GCM_SIV_TAG_LEN];
789 gcm_siv_polyval(expected_tag, out, in_len, ad, ad_len, keys.auth_key, nonce);
790 keys.enc_block(expected_tag, expected_tag, &keys.enc_key.ks);
791
792 if (CRYPTO_memcmp(expected_tag, in_tag, sizeof(expected_tag)) != 0) {
793 OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
794 return 0;
795 }
796
797 return 1;
798 }
799
800 static const EVP_AEAD aead_aes_128_gcm_siv = {
801 16, // key length
802 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length
803 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead
804 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length
805 0, // seal_scatter_supports_extra_in
806
807 aead_aes_gcm_siv_init,
808 NULL /* init_with_direction */,
809 aead_aes_gcm_siv_cleanup,
810 NULL /* open */,
811 aead_aes_gcm_siv_seal_scatter,
812 aead_aes_gcm_siv_open_gather,
813 NULL /* get_iv */,
814 NULL /* tag_len */,
815 };
816
817 static const EVP_AEAD aead_aes_256_gcm_siv = {
818 32, // key length
819 EVP_AEAD_AES_GCM_SIV_NONCE_LEN, // nonce length
820 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // overhead
821 EVP_AEAD_AES_GCM_SIV_TAG_LEN, // max tag length
822 0, // seal_scatter_supports_extra_in
823
824 aead_aes_gcm_siv_init,
825 NULL /* init_with_direction */,
826 aead_aes_gcm_siv_cleanup,
827 NULL /* open */,
828 aead_aes_gcm_siv_seal_scatter,
829 aead_aes_gcm_siv_open_gather,
830 NULL /* get_iv */,
831 NULL /* tag_len */,
832 };
833
834 #if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM)
835
avx_aesni_capable(void)836 static char avx_aesni_capable(void) {
837 const uint32_t ecx = OPENSSL_ia32cap_P[1];
838
839 return (ecx & (1 << (57 - 32))) != 0 /* AESNI */ &&
840 (ecx & (1 << 28)) != 0 /* AVX */;
841 }
842
EVP_aead_aes_128_gcm_siv(void)843 const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void) {
844 if (avx_aesni_capable()) {
845 return &aead_aes_128_gcm_siv_asm;
846 }
847 return &aead_aes_128_gcm_siv;
848 }
849
EVP_aead_aes_256_gcm_siv(void)850 const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void) {
851 if (avx_aesni_capable()) {
852 return &aead_aes_256_gcm_siv_asm;
853 }
854 return &aead_aes_256_gcm_siv;
855 }
856
857 #else
858
EVP_aead_aes_128_gcm_siv(void)859 const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void) {
860 return &aead_aes_128_gcm_siv;
861 }
862
EVP_aead_aes_256_gcm_siv(void)863 const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void) {
864 return &aead_aes_256_gcm_siv;
865 }
866
867 #endif // X86_64 && !NO_ASM
868