providers/implementations/ciphers/cipher_aes_xts.c

   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  */
  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  */
  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
  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
 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
 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
 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
 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
 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
 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
 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
 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
 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);