providers/implementations/ciphers/cipher_aes_xts.c

   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 /*
  11  * AES low level APIs are deprecated for public use, but still ok for internal
  12  * use where we're using them to implement the higher level EVP interface, as is
  13  * the case here.
  14  */
  15 #include "internal/deprecated.h"
  16
  17 #include "cipher_aes_xts.h"
  18 #include "prov/implementations.h"
  19 #include "prov/providercommonerr.h"
  20
  21 /* TODO (3.0) Figure out what flags need to be set */
  22 #define AES_XTS_FLAGS (EVP_CIPH_CUSTOM_IV          \
  23                        | EVP_CIPH_ALWAYS_CALL_INIT \
  24                        | EVP_CIPH_CTRL_INIT        \
  25                        | EVP_CIPH_CUSTOM_COPY)
  26
  27 #define AES_XTS_IV_BITS 128
  28 #define AES_XTS_BLOCK_BITS 8
  29
  30 /* forward declarations */
  31 static OSSL_OP_cipher_encrypt_init_fn aes_xts_einit;
  32 static OSSL_OP_cipher_decrypt_init_fn aes_xts_dinit;
  33 static OSSL_OP_cipher_update_fn aes_xts_stream_update;
  34 static OSSL_OP_cipher_final_fn aes_xts_stream_final;
  35 static OSSL_OP_cipher_cipher_fn aes_xts_cipher;
  36 static OSSL_OP_cipher_freectx_fn aes_xts_freectx;
  37 static OSSL_OP_cipher_dupctx_fn aes_xts_dupctx;
  38 static OSSL_OP_cipher_set_ctx_params_fn aes_xts_set_ctx_params;
  39 static OSSL_OP_cipher_settable_ctx_params_fn aes_xts_settable_ctx_params;
  40
  41 /*
  42  * Verify that the two keys are different.
  43  *
  44  * This addresses the vulnerability described in Rogaway's
  45  * September 2004 paper:
  46  *
  47  *      "Efficient Instantiations of Tweakable Blockciphers and
  48  *       Refinements to Modes OCB and PMAC".
  49  *      (http://web.cs.ucdavis.edu/~rogaway/papers/offsets.pdf)
  50  *
  51  * FIPS 140-2 IG A.9 XTS-AES Key Generation Requirements states
  52  * that:
  53  *      "The check for Key_1 != Key_2 shall be done at any place
  54  *       BEFORE using the keys in the XTS-AES algorithm to process
  55  *       data with them."
  56  */
  57 static int aes_xts_check_keys_differ(const unsigned char *key, size_t bytes,
  58                                      int enc)
  59 {
  60     if ((!allow_insecure_decrypt || enc)
  61             && CRYPTO_memcmp(key, key + bytes, bytes) == 0) {
  62         ERR_raise(ERR_LIB_PROV, PROV_R_XTS_DUPLICATED_KEYS);
  63         return 0;
  64     }
  65     return 1;
  66 }
  67
  68 /*-
  69  * Provider dispatch functions
  70  */
  71 static int aes_xts_init(void *vctx, const unsigned char *key, size_t keylen,
  72                         const unsigned char *iv, size_t ivlen, int enc)
  73 {
  74     PROV_AES_XTS_CTX *xctx = (PROV_AES_XTS_CTX *)vctx;
  75     PROV_CIPHER_CTX *ctx = &xctx->base;
  76
  77     ctx->enc = enc;
  78
  79     if (iv != NULL) {
  80         if (!cipher_generic_initiv(vctx, iv, ivlen))
  81             return 0;
  82     }
  83     if (key != NULL) {
  84         if (keylen != ctx->keylen) {
  85             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
  86             return 0;
  87         }
  88         if (!aes_xts_check_keys_differ(key, keylen / 2, enc))
  89             return 0;
  90         return ctx->hw->init(ctx, key, keylen);
  91     }
  92     return 1;
  93 }
  94
  95 static int aes_xts_einit(void *vctx, const unsigned char *key, size_t keylen,
  96                          const unsigned char *iv, size_t ivlen)
  97 {
  98     return aes_xts_init(vctx, key, keylen, iv, ivlen, 1);
  99 }
 100
 101 static int aes_xts_dinit(void *vctx, const unsigned char *key, size_t keylen,
 102                          const unsigned char *iv, size_t ivlen)
 103 {
 104     return aes_xts_init(vctx, key, keylen, iv, ivlen, 0);
 105 }
 106
 107 static void *aes_xts_newctx(void *provctx, unsigned int mode, uint64_t flags,
 108                             size_t kbits, size_t blkbits, size_t ivbits)
 109 {
 110     PROV_AES_XTS_CTX *ctx = OPENSSL_zalloc(sizeof(*ctx));
 111
 112     if (ctx != NULL) {
 113         cipher_generic_initkey(&ctx->base, kbits, blkbits, ivbits, mode, flags,
 114                                PROV_CIPHER_HW_aes_xts(kbits), NULL);
 115     }
 116     return ctx;
 117 }
 118
 119 static void aes_xts_freectx(void *vctx)
 120 {
 121     PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
 122
 123     OPENSSL_clear_free(ctx,  sizeof(*ctx));
 124 }
 125
 126 static void *aes_xts_dupctx(void *vctx)
 127 {
 128     PROV_AES_XTS_CTX *in = (PROV_AES_XTS_CTX *)vctx;
 129     PROV_AES_XTS_CTX *ret = NULL;
 130
 131     if (in->xts.key1 != NULL) {
 132         if (in->xts.key1 != &in->ks1)
 133             return NULL;
 134     }
 135     if (in->xts.key2 != NULL) {
 136         if (in->xts.key2 != &in->ks2)
 137             return NULL;
 138     }
 139     ret = OPENSSL_malloc(sizeof(*ret));
 140     if (ret == NULL) {
 141         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 142         return NULL;
 143     }
 144     in->base.hw->copyctx(&ret->base, &in->base);
 145     return ret;
 146 }
 147
 148 static int aes_xts_cipher(void *vctx, unsigned char *out, size_t *outl,
 149                           size_t outsize, const unsigned char *in, size_t inl)
 150 {
 151     PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
 152
 153     if (ctx->xts.key1 == NULL
 154             || ctx->xts.key2 == NULL
 155             || !ctx->base.iv_set
 156             || out == NULL
 157             || in == NULL
 158             || inl < AES_BLOCK_SIZE)
 159         return 0;
 160
 161     /*
 162      * Impose a limit of 2^20 blocks per data unit as specified by
 163      * IEEE Std 1619-2018.  The earlier and obsolete IEEE Std 1619-2007
 164      * indicated that this was a SHOULD NOT rather than a MUST NOT.
 165      * NIST SP 800-38E mandates the same limit.
 166      */
 167     if (inl > XTS_MAX_BLOCKS_PER_DATA_UNIT * AES_BLOCK_SIZE) {
 168         ERR_raise(ERR_LIB_PROV, PROV_R_XTS_DATA_UNIT_IS_TOO_LARGE);
 169         return 0;
 170     }
 171
 172     if (ctx->stream != NULL)
 173         (*ctx->stream)(in, out, inl, ctx->xts.key1, ctx->xts.key2, ctx->base.iv);
 174     else if (CRYPTO_xts128_encrypt(&ctx->xts, ctx->base.iv, in, out, inl,
 175                                    ctx->base.enc))
 176         return 0;
 177
 178     *outl = inl;
 179     return 1;
 180 }
 181
 182 static int aes_xts_stream_update(void *vctx, unsigned char *out, size_t *outl,
 183                                  size_t outsize, const unsigned char *in,
 184                                  size_t inl)
 185 {
 186     PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
 187
 188     if (outsize < inl) {
 189         ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 190         return 0;
 191     }
 192
 193     if (!aes_xts_cipher(ctx, out, outl, outsize, in, inl)) {
 194         ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);
 195         return 0;
 196     }
 197
 198     return 1;
 199 }
 200
 201 static int aes_xts_stream_final(void *vctx, unsigned char *out, size_t *outl,
 202                                 size_t outsize)
 203 {
 204     *outl = 0;
 205     return 1;
 206 }
 207
 208 static const OSSL_PARAM aes_xts_known_settable_ctx_params[] = {
 209     OSSL_PARAM_size_t(OSSL_CIPHER_PARAM_KEYLEN, NULL),
 210     OSSL_PARAM_END
 211 };
 212
 213 static const OSSL_PARAM *aes_xts_settable_ctx_params(void)
 214 {
 215     return aes_xts_known_settable_ctx_params;
 216 }
 217
 218 static int aes_xts_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 219 {
 220     PROV_CIPHER_CTX *ctx = (PROV_CIPHER_CTX *)vctx;
 221     const OSSL_PARAM *p;
 222
 223     /*
 224      * TODO(3.0) We need a general solution for handling missing parameters
 225      * inside set_params and get_params methods.
 226      */
 227     p = OSSL_PARAM_locate_const(params, OSSL_CIPHER_PARAM_KEYLEN);
 228     if (p != NULL) {
 229         size_t keylen;
 230
 231         if (!OSSL_PARAM_get_size_t(p, &keylen)) {
 232             ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);
 233             return 0;
 234         }
 235         /* The key length can not be modified for xts mode */
 236         if (keylen != ctx->keylen)
 237             return 0;
 238     }
 239
 240     return 1;
 241 }
 242
 243 #define IMPLEMENT_cipher(lcmode, UCMODE, kbits, flags)                         \
 244 static OSSL_OP_cipher_get_params_fn aes_##kbits##_##lcmode##_get_params;       \
 245 static int aes_##kbits##_##lcmode##_get_params(OSSL_PARAM params[])            \
 246 {                                                                              \
 247     return cipher_generic_get_params(params, EVP_CIPH_##UCMODE##_MODE,         \
 248                                      flags, 2 * kbits, AES_XTS_BLOCK_BITS,     \
 249                                      AES_XTS_IV_BITS);                         \
 250 }                                                                              \
 251 static OSSL_OP_cipher_newctx_fn aes_##kbits##_xts_newctx;                      \
 252 static void *aes_##kbits##_xts_newctx(void *provctx)                           \
 253 {                                                                              \
 254     return aes_xts_newctx(provctx, EVP_CIPH_##UCMODE##_MODE, flags, 2 * kbits, \
 255                           AES_XTS_BLOCK_BITS, AES_XTS_IV_BITS);                \
 256 }                                                                              \
 257 const OSSL_DISPATCH aes##kbits##xts_functions[] = {                            \
 258     { OSSL_FUNC_CIPHER_NEWCTX, (void (*)(void))aes_##kbits##_xts_newctx },     \
 259     { OSSL_FUNC_CIPHER_ENCRYPT_INIT, (void (*)(void))aes_xts_einit },          \
 260     { OSSL_FUNC_CIPHER_DECRYPT_INIT, (void (*)(void))aes_xts_dinit },          \
 261     { OSSL_FUNC_CIPHER_UPDATE, (void (*)(void))aes_xts_stream_update },        \
 262     { OSSL_FUNC_CIPHER_FINAL, (void (*)(void))aes_xts_stream_final },          \
 263     { OSSL_FUNC_CIPHER_CIPHER, (void (*)(void))aes_xts_cipher },               \
 264     { OSSL_FUNC_CIPHER_FREECTX, (void (*)(void))aes_xts_freectx },             \
 265     { OSSL_FUNC_CIPHER_DUPCTX, (void (*)(void))aes_xts_dupctx },               \
 266     { OSSL_FUNC_CIPHER_GET_PARAMS,                                             \
 267       (void (*)(void))aes_##kbits##_##lcmode##_get_params },                   \
 268     { OSSL_FUNC_CIPHER_GETTABLE_PARAMS,                                        \
 269       (void (*)(void))cipher_generic_gettable_params },                        \
 270     { OSSL_FUNC_CIPHER_GET_CTX_PARAMS,                                         \
 271       (void (*)(void))cipher_generic_get_ctx_params },                         \
 272     { OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS,                                    \
 273       (void (*)(void))cipher_generic_gettable_ctx_params },                    \
 274     { OSSL_FUNC_CIPHER_SET_CTX_PARAMS,                                         \
 275       (void (*)(void))aes_xts_set_ctx_params },                                \
 276     { OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS,                                    \
 277      (void (*)(void))aes_xts_settable_ctx_params },                            \
 278     { 0, NULL }                                                                \
 279 }
 280
 281 IMPLEMENT_cipher(xts, XTS, 256, AES_XTS_FLAGS);
 282 IMPLEMENT_cipher(xts, XTS, 128, AES_XTS_FLAGS);