1
2 /*
3 * Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
4 *
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
9 */
10
11 /*
12 * AES low level APIs are deprecated for public use, but still ok for internal
13 * use where we're using them to implement the higher level EVP interface, as is
14 * the case here.
15 */
16 #include "internal/deprecated.h"
17
18 #include <openssl/proverr.h>
19 #include "cipher_aes_xts.h"
20 #include "prov/implementations.h"
21 #include "prov/providercommon.h"
22
23 #define AES_XTS_FLAGS PROV_CIPHER_FLAG_CUSTOM_IV
24 #define AES_XTS_IV_BITS 128
25 #define AES_XTS_BLOCK_BITS 8
26
27 /* forward declarations */
28 static OSSL_FUNC_cipher_encrypt_init_fn aes_xts_einit;
29 static OSSL_FUNC_cipher_decrypt_init_fn aes_xts_dinit;
30 static OSSL_FUNC_cipher_update_fn aes_xts_stream_update;
31 static OSSL_FUNC_cipher_final_fn aes_xts_stream_final;
32 static OSSL_FUNC_cipher_cipher_fn aes_xts_cipher;
33 static OSSL_FUNC_cipher_freectx_fn aes_xts_freectx;
34 static OSSL_FUNC_cipher_dupctx_fn aes_xts_dupctx;
35 static OSSL_FUNC_cipher_set_ctx_params_fn aes_xts_set_ctx_params;
36 static OSSL_FUNC_cipher_settable_ctx_params_fn aes_xts_settable_ctx_params;
37
38 /*
39 * Verify that the two keys are different.
40 *
41 * This addresses the vulnerability described in Rogaway's
42 * September 2004 paper:
43 *
44 * "Efficient Instantiations of Tweakable Blockciphers and
45 * Refinements to Modes OCB and PMAC".
46 * (http://web.cs.ucdavis.edu/~rogaway/papers/offsets.pdf)
47 *
48 * FIPS 140-2 IG A.9 XTS-AES Key Generation Requirements states
49 * that:
50 * "The check for Key_1 != Key_2 shall be done at any place
51 * BEFORE using the keys in the XTS-AES algorithm to process
52 * data with them."
53 */
aes_xts_check_keys_differ(const unsigned char * key,size_t bytes,int enc)54 static int aes_xts_check_keys_differ(const unsigned char *key, size_t bytes,
55 int enc)
56 {
57 if ((!ossl_aes_xts_allow_insecure_decrypt || enc)
58 && CRYPTO_memcmp(key, key + bytes, bytes) == 0) {
59 ERR_raise(ERR_LIB_PROV, PROV_R_XTS_DUPLICATED_KEYS);
60 return 0;
61 }
62 return 1;
63 }
64
65 /*-
66 * Provider dispatch functions
67 */
aes_xts_init(void * vctx,const unsigned char * key,size_t keylen,const unsigned char * iv,size_t ivlen,const OSSL_PARAM params[],int enc)68 static int aes_xts_init(void *vctx, const unsigned char *key, size_t keylen,
69 const unsigned char *iv, size_t ivlen,
70 const OSSL_PARAM params[], int enc)
71 {
72 PROV_AES_XTS_CTX *xctx = (PROV_AES_XTS_CTX *)vctx;
73 PROV_CIPHER_CTX *ctx = &xctx->base;
74
75 if (!ossl_prov_is_running())
76 return 0;
77
78 ctx->enc = enc;
79
80 if (iv != NULL) {
81 if (!ossl_cipher_generic_initiv(vctx, iv, ivlen))
82 return 0;
83 }
84 if (key != NULL) {
85 if (keylen != ctx->keylen) {
86 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
87 return 0;
88 }
89 if (!aes_xts_check_keys_differ(key, keylen / 2, enc))
90 return 0;
91 if (!ctx->hw->init(ctx, key, keylen))
92 return 0;
93 }
94 return aes_xts_set_ctx_params(ctx, params);
95 }
96
aes_xts_einit(void * vctx,const unsigned char * key,size_t keylen,const unsigned char * iv,size_t ivlen,const OSSL_PARAM params[])97 static int aes_xts_einit(void *vctx, const unsigned char *key, size_t keylen,
98 const unsigned char *iv, size_t ivlen,
99 const OSSL_PARAM params[])
100 {
101 return aes_xts_init(vctx, key, keylen, iv, ivlen, params, 1);
102 }
103
aes_xts_dinit(void * vctx,const unsigned char * key,size_t keylen,const unsigned char * iv,size_t ivlen,const OSSL_PARAM params[])104 static int aes_xts_dinit(void *vctx, const unsigned char *key, size_t keylen,
105 const unsigned char *iv, size_t ivlen,
106 const OSSL_PARAM params[])
107 {
108 return aes_xts_init(vctx, key, keylen, iv, ivlen, params, 0);
109 }
110
aes_xts_newctx(void * provctx,unsigned int mode,uint64_t flags,size_t kbits,size_t blkbits,size_t ivbits)111 static void *aes_xts_newctx(void *provctx, unsigned int mode, uint64_t flags,
112 size_t kbits, size_t blkbits, size_t ivbits)
113 {
114 PROV_AES_XTS_CTX *ctx = OPENSSL_zalloc(sizeof(*ctx));
115
116 if (ctx != NULL) {
117 ossl_cipher_generic_initkey(&ctx->base, kbits, blkbits, ivbits, mode,
118 flags, ossl_prov_cipher_hw_aes_xts(kbits),
119 NULL);
120 }
121 return ctx;
122 }
123
aes_xts_freectx(void * vctx)124 static void aes_xts_freectx(void *vctx)
125 {
126 PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
127
128 ossl_cipher_generic_reset_ctx((PROV_CIPHER_CTX *)vctx);
129 OPENSSL_clear_free(ctx, sizeof(*ctx));
130 }
131
aes_xts_dupctx(void * vctx)132 static void *aes_xts_dupctx(void *vctx)
133 {
134 PROV_AES_XTS_CTX *in = (PROV_AES_XTS_CTX *)vctx;
135 PROV_AES_XTS_CTX *ret = NULL;
136
137 if (!ossl_prov_is_running())
138 return NULL;
139
140 if (in->xts.key1 != NULL) {
141 if (in->xts.key1 != &in->ks1)
142 return NULL;
143 }
144 if (in->xts.key2 != NULL) {
145 if (in->xts.key2 != &in->ks2)
146 return NULL;
147 }
148 ret = OPENSSL_malloc(sizeof(*ret));
149 if (ret == NULL) {
150 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
151 return NULL;
152 }
153 in->base.hw->copyctx(&ret->base, &in->base);
154 return ret;
155 }
156
aes_xts_cipher(void * vctx,unsigned char * out,size_t * outl,size_t outsize,const unsigned char * in,size_t inl)157 static int aes_xts_cipher(void *vctx, unsigned char *out, size_t *outl,
158 size_t outsize, const unsigned char *in, size_t inl)
159 {
160 PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
161
162 if (!ossl_prov_is_running()
163 || ctx->xts.key1 == NULL
164 || ctx->xts.key2 == NULL
165 || !ctx->base.iv_set
166 || out == NULL
167 || in == NULL
168 || inl < AES_BLOCK_SIZE)
169 return 0;
170
171 /*
172 * Impose a limit of 2^20 blocks per data unit as specified by
173 * IEEE Std 1619-2018. The earlier and obsolete IEEE Std 1619-2007
174 * indicated that this was a SHOULD NOT rather than a MUST NOT.
175 * NIST SP 800-38E mandates the same limit.
176 */
177 if (inl > XTS_MAX_BLOCKS_PER_DATA_UNIT * AES_BLOCK_SIZE) {
178 ERR_raise(ERR_LIB_PROV, PROV_R_XTS_DATA_UNIT_IS_TOO_LARGE);
179 return 0;
180 }
181
182 if (ctx->stream != NULL)
183 (*ctx->stream)(in, out, inl, ctx->xts.key1, ctx->xts.key2, ctx->base.iv);
184 else if (CRYPTO_xts128_encrypt(&ctx->xts, ctx->base.iv, in, out, inl,
185 ctx->base.enc))
186 return 0;
187
188 *outl = inl;
189 return 1;
190 }
191
aes_xts_stream_update(void * vctx,unsigned char * out,size_t * outl,size_t outsize,const unsigned char * in,size_t inl)192 static int aes_xts_stream_update(void *vctx, unsigned char *out, size_t *outl,
193 size_t outsize, const unsigned char *in,
194 size_t inl)
195 {
196 PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
197
198 if (outsize < inl) {
199 ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
200 return 0;
201 }
202
203 if (!aes_xts_cipher(ctx, out, outl, outsize, in, inl)) {
204 ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);
205 return 0;
206 }
207
208 return 1;
209 }
210
aes_xts_stream_final(void * vctx,unsigned char * out,size_t * outl,size_t outsize)211 static int aes_xts_stream_final(void *vctx, unsigned char *out, size_t *outl,
212 size_t outsize)
213 {
214 if (!ossl_prov_is_running())
215 return 0;
216 *outl = 0;
217 return 1;
218 }
219
220 static const OSSL_PARAM aes_xts_known_settable_ctx_params[] = {
221 OSSL_PARAM_size_t(OSSL_CIPHER_PARAM_KEYLEN, NULL),
222 OSSL_PARAM_END
223 };
224
aes_xts_settable_ctx_params(ossl_unused void * cctx,ossl_unused void * provctx)225 static const OSSL_PARAM *aes_xts_settable_ctx_params(ossl_unused void *cctx,
226 ossl_unused void *provctx)
227 {
228 return aes_xts_known_settable_ctx_params;
229 }
230
aes_xts_set_ctx_params(void * vctx,const OSSL_PARAM params[])231 static int aes_xts_set_ctx_params(void *vctx, const OSSL_PARAM params[])
232 {
233 PROV_CIPHER_CTX *ctx = (PROV_CIPHER_CTX *)vctx;
234 const OSSL_PARAM *p;
235
236 if (params == NULL)
237 return 1;
238
239 p = OSSL_PARAM_locate_const(params, OSSL_CIPHER_PARAM_KEYLEN);
240 if (p != NULL) {
241 size_t keylen;
242
243 if (!OSSL_PARAM_get_size_t(p, &keylen)) {
244 ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);
245 return 0;
246 }
247 /* The key length can not be modified for xts mode */
248 if (keylen != ctx->keylen)
249 return 0;
250 }
251
252 return 1;
253 }
254
255 #define IMPLEMENT_cipher(lcmode, UCMODE, kbits, flags) \
256 static OSSL_FUNC_cipher_get_params_fn aes_##kbits##_##lcmode##_get_params; \
257 static int aes_##kbits##_##lcmode##_get_params(OSSL_PARAM params[]) \
258 { \
259 return ossl_cipher_generic_get_params(params, EVP_CIPH_##UCMODE##_MODE, \
260 flags, 2 * kbits, AES_XTS_BLOCK_BITS, \
261 AES_XTS_IV_BITS); \
262 } \
263 static OSSL_FUNC_cipher_newctx_fn aes_##kbits##_xts_newctx; \
264 static void *aes_##kbits##_xts_newctx(void *provctx) \
265 { \
266 return aes_xts_newctx(provctx, EVP_CIPH_##UCMODE##_MODE, flags, 2 * kbits, \
267 AES_XTS_BLOCK_BITS, AES_XTS_IV_BITS); \
268 } \
269 const OSSL_DISPATCH ossl_aes##kbits##xts_functions[] = { \
270 { OSSL_FUNC_CIPHER_NEWCTX, (void (*)(void))aes_##kbits##_xts_newctx }, \
271 { OSSL_FUNC_CIPHER_ENCRYPT_INIT, (void (*)(void))aes_xts_einit }, \
272 { OSSL_FUNC_CIPHER_DECRYPT_INIT, (void (*)(void))aes_xts_dinit }, \
273 { OSSL_FUNC_CIPHER_UPDATE, (void (*)(void))aes_xts_stream_update }, \
274 { OSSL_FUNC_CIPHER_FINAL, (void (*)(void))aes_xts_stream_final }, \
275 { OSSL_FUNC_CIPHER_CIPHER, (void (*)(void))aes_xts_cipher }, \
276 { OSSL_FUNC_CIPHER_FREECTX, (void (*)(void))aes_xts_freectx }, \
277 { OSSL_FUNC_CIPHER_DUPCTX, (void (*)(void))aes_xts_dupctx }, \
278 { OSSL_FUNC_CIPHER_GET_PARAMS, \
279 (void (*)(void))aes_##kbits##_##lcmode##_get_params }, \
280 { OSSL_FUNC_CIPHER_GETTABLE_PARAMS, \
281 (void (*)(void))ossl_cipher_generic_gettable_params }, \
282 { OSSL_FUNC_CIPHER_GET_CTX_PARAMS, \
283 (void (*)(void))ossl_cipher_generic_get_ctx_params }, \
284 { OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS, \
285 (void (*)(void))ossl_cipher_generic_gettable_ctx_params }, \
286 { OSSL_FUNC_CIPHER_SET_CTX_PARAMS, \
287 (void (*)(void))aes_xts_set_ctx_params }, \
288 { OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS, \
289 (void (*)(void))aes_xts_settable_ctx_params }, \
290 { 0, NULL } \
291 }
292
293 IMPLEMENT_cipher(xts, XTS, 256, AES_XTS_FLAGS);
294 IMPLEMENT_cipher(xts, XTS, 128, AES_XTS_FLAGS);
295