1/*
2 * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include "cipher_aes_xts.h"
11#include "prov/implementations.h"
12#include "prov/providercommonerr.h"
13
14/* TODO (3.0) Figure out what flags need to be set */
15#define AES_XTS_FLAGS (EVP_CIPH_CUSTOM_IV \
16 | EVP_CIPH_ALWAYS_CALL_INIT \
17 | EVP_CIPH_CTRL_INIT \
18 | EVP_CIPH_CUSTOM_COPY)
19
20#define AES_XTS_IV_BITS 128
21#define AES_XTS_BLOCK_BITS 8
22
23/* forward declarations */
24static OSSL_OP_cipher_encrypt_init_fn aes_xts_einit;
25static OSSL_OP_cipher_decrypt_init_fn aes_xts_dinit;
26static OSSL_OP_cipher_update_fn aes_xts_stream_update;
27static OSSL_OP_cipher_final_fn aes_xts_stream_final;
28static OSSL_OP_cipher_cipher_fn aes_xts_cipher;
29static OSSL_OP_cipher_freectx_fn aes_xts_freectx;
30static OSSL_OP_cipher_dupctx_fn aes_xts_dupctx;
31static OSSL_OP_cipher_set_ctx_params_fn aes_xts_set_ctx_params;
32static OSSL_OP_cipher_settable_ctx_params_fn aes_xts_settable_ctx_params;
33
34/*
35 * Verify that the two keys are different.
36 *
37 * This addresses the vulnerability described in Rogaway's
38 * September 2004 paper:
39 *
40 * "Efficient Instantiations of Tweakable Blockciphers and
41 * Refinements to Modes OCB and PMAC".
42 * (http://web.cs.ucdavis.edu/~rogaway/papers/offsets.pdf)
43 *
44 * FIPS 140-2 IG A.9 XTS-AES Key Generation Requirements states
45 * that:
46 * "The check for Key_1 != Key_2 shall be done at any place
47 * BEFORE using the keys in the XTS-AES algorithm to process
48 * data with them."
49 */
50static int aes_xts_check_keys_differ(const unsigned char *key, size_t bytes,
51 int enc)
52{
53 if ((!allow_insecure_decrypt || enc)
54 && CRYPTO_memcmp(key, key + bytes, bytes) == 0) {
55 ERR_raise(ERR_LIB_PROV, PROV_R_XTS_DUPLICATED_KEYS);
56 return 0;
57 }
58 return 1;
59}
60
61/*-
62 * Provider dispatch functions
63 */
64static int aes_xts_init(void *vctx, const unsigned char *key, size_t keylen,
65 const unsigned char *iv, size_t ivlen, int enc)
66{
67 PROV_AES_XTS_CTX *xctx = (PROV_AES_XTS_CTX *)vctx;
68 PROV_CIPHER_CTX *ctx = &xctx->base;
69
70 ctx->enc = enc;
71
72 if (iv != NULL) {
73 if (!cipher_generic_initiv(vctx, iv, ivlen))
74 return 0;
75 }
76 if (key != NULL) {
77 if (keylen != ctx->keylen) {
78 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
79 return 0;
80 }
81 if (!aes_xts_check_keys_differ(key, keylen / 2, enc))
82 return 0;
83 return ctx->hw->init(ctx, key, keylen);
84 }
85 return 1;
86}
87
88static int aes_xts_einit(void *vctx, const unsigned char *key, size_t keylen,
89 const unsigned char *iv, size_t ivlen)
90{
91 return aes_xts_init(vctx, key, keylen, iv, ivlen, 1);
92}
93
94static int aes_xts_dinit(void *vctx, const unsigned char *key, size_t keylen,
95 const unsigned char *iv, size_t ivlen)
96{
97 return aes_xts_init(vctx, key, keylen, iv, ivlen, 0);
98}
99
100static void *aes_xts_newctx(void *provctx, unsigned int mode, uint64_t flags,
101 size_t kbits, size_t blkbits, size_t ivbits)
102{
103 PROV_AES_XTS_CTX *ctx = OPENSSL_zalloc(sizeof(*ctx));
104
105 if (ctx != NULL) {
106 cipher_generic_initkey(&ctx->base, kbits, blkbits, ivbits, mode, flags,
107 PROV_CIPHER_HW_aes_xts(kbits), NULL);
108 }
109 return ctx;
110}
111
112static void aes_xts_freectx(void *vctx)
113{
114 PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
115
116 OPENSSL_clear_free(ctx, sizeof(*ctx));
117}
118
119static void *aes_xts_dupctx(void *vctx)
120{
121 PROV_AES_XTS_CTX *in = (PROV_AES_XTS_CTX *)vctx;
122 PROV_AES_XTS_CTX *ret = NULL;
123
124 if (in->xts.key1 != NULL) {
125 if (in->xts.key1 != &in->ks1)
126 return NULL;
127 }
128 if (in->xts.key2 != NULL) {
129 if (in->xts.key2 != &in->ks2)
130 return NULL;
131 }
132 ret = OPENSSL_malloc(sizeof(*ret));
133 if (ret == NULL) {
134 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
135 return NULL;
136 }
137 in->base.hw->copyctx(&ret->base, &in->base);
138 return ret;
139}
140
141static int aes_xts_cipher(void *vctx, unsigned char *out, size_t *outl,
142 size_t outsize, const unsigned char *in, size_t inl)
143{
144 PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
145
146 if (ctx->xts.key1 == NULL
147 || ctx->xts.key2 == NULL
148 || !ctx->base.iv_set
149 || out == NULL
150 || in == NULL
151 || inl < AES_BLOCK_SIZE)
152 return 0;
153
154 /*
155 * Impose a limit of 2^20 blocks per data unit as specified by
156 * IEEE Std 1619-2018. The earlier and obsolete IEEE Std 1619-2007
157 * indicated that this was a SHOULD NOT rather than a MUST NOT.
158 * NIST SP 800-38E mandates the same limit.
159 */
160 if (inl > XTS_MAX_BLOCKS_PER_DATA_UNIT * AES_BLOCK_SIZE) {
161 ERR_raise(ERR_LIB_PROV, PROV_R_XTS_DATA_UNIT_IS_TOO_LARGE);
162 return 0;
163 }
164
165 if (ctx->stream != NULL)
166 (*ctx->stream)(in, out, inl, ctx->xts.key1, ctx->xts.key2, ctx->base.iv);
167 else if (CRYPTO_xts128_encrypt(&ctx->xts, ctx->base.iv, in, out, inl,
168 ctx->base.enc))
169 return 0;
170
171 *outl = inl;
172 return 1;
173}
174
175static int aes_xts_stream_update(void *vctx, unsigned char *out, size_t *outl,
176 size_t outsize, const unsigned char *in,
177 size_t inl)
178{
179 PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
180
181 if (outsize < inl) {
182 ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
183 return 0;
184 }
185
186 if (!aes_xts_cipher(ctx, out, outl, outsize, in, inl)) {
187 ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);
188 return 0;
189 }
190
191 return 1;
192}
193
194static int aes_xts_stream_final(void *vctx, unsigned char *out, size_t *outl,
195 size_t outsize)
196{
197 *outl = 0;
198 return 1;
199}
200
201static const OSSL_PARAM aes_xts_known_settable_ctx_params[] = {
202 OSSL_PARAM_size_t(OSSL_CIPHER_PARAM_KEYLEN, NULL),
203 OSSL_PARAM_END
204};
205
206static const OSSL_PARAM *aes_xts_settable_ctx_params(void)
207{
208 return aes_xts_known_settable_ctx_params;
209}
210
211static int aes_xts_set_ctx_params(void *vctx, const OSSL_PARAM params[])
212{
213 PROV_CIPHER_CTX *ctx = (PROV_CIPHER_CTX *)vctx;
214 const OSSL_PARAM *p;
215
216 /*
217 * TODO(3.0) We need a general solution for handling missing parameters
218 * inside set_params and get_params methods.
219 */
220 p = OSSL_PARAM_locate_const(params, OSSL_CIPHER_PARAM_KEYLEN);
221 if (p != NULL) {
222 size_t keylen;
223
224 if (!OSSL_PARAM_get_size_t(p, &keylen)) {
225 ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);
226 return 0;
227 }
228 /* The key length can not be modified for xts mode */
229 if (keylen != ctx->keylen)
230 return 0;
231 }
232
233 return 1;
234}
235
236#define IMPLEMENT_cipher(lcmode, UCMODE, kbits, flags) \
237static OSSL_OP_cipher_get_params_fn aes_##kbits##_##lcmode##_get_params; \
238static int aes_##kbits##_##lcmode##_get_params(OSSL_PARAM params[]) \
239{ \
240 return cipher_generic_get_params(params, EVP_CIPH_##UCMODE##_MODE, \
241 flags, 2 * kbits, AES_XTS_BLOCK_BITS, \
242 AES_XTS_IV_BITS); \
243} \
244static OSSL_OP_cipher_newctx_fn aes_##kbits##_xts_newctx; \
245static void *aes_##kbits##_xts_newctx(void *provctx) \
246{ \
247 return aes_xts_newctx(provctx, EVP_CIPH_##UCMODE##_MODE, flags, 2 * kbits, \
248 AES_XTS_BLOCK_BITS, AES_XTS_IV_BITS); \
249} \
250const OSSL_DISPATCH aes##kbits##xts_functions[] = { \
251 { OSSL_FUNC_CIPHER_NEWCTX, (void (*)(void))aes_##kbits##_xts_newctx }, \
252 { OSSL_FUNC_CIPHER_ENCRYPT_INIT, (void (*)(void))aes_xts_einit }, \
253 { OSSL_FUNC_CIPHER_DECRYPT_INIT, (void (*)(void))aes_xts_dinit }, \
254 { OSSL_FUNC_CIPHER_UPDATE, (void (*)(void))aes_xts_stream_update }, \
255 { OSSL_FUNC_CIPHER_FINAL, (void (*)(void))aes_xts_stream_final }, \
256 { OSSL_FUNC_CIPHER_CIPHER, (void (*)(void))aes_xts_cipher }, \
257 { OSSL_FUNC_CIPHER_FREECTX, (void (*)(void))aes_xts_freectx }, \
258 { OSSL_FUNC_CIPHER_DUPCTX, (void (*)(void))aes_xts_dupctx }, \
259 { OSSL_FUNC_CIPHER_GET_PARAMS, \
260 (void (*)(void))aes_##kbits##_##lcmode##_get_params }, \
261 { OSSL_FUNC_CIPHER_GETTABLE_PARAMS, \
262 (void (*)(void))cipher_generic_gettable_params }, \
263 { OSSL_FUNC_CIPHER_GET_CTX_PARAMS, \
264 (void (*)(void))cipher_generic_get_ctx_params }, \
265 { OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS, \
266 (void (*)(void))cipher_generic_gettable_ctx_params }, \
267 { OSSL_FUNC_CIPHER_SET_CTX_PARAMS, \
268 (void (*)(void))aes_xts_set_ctx_params }, \
269 { OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS, \
270 (void (*)(void))aes_xts_settable_ctx_params }, \
271 { 0, NULL } \
272}
273
274IMPLEMENT_cipher(xts, XTS, 256, AES_XTS_FLAGS);
275IMPLEMENT_cipher(xts, XTS, 128, AES_XTS_FLAGS);
276