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         return NULL;
 151     in->base.hw->copyctx(&ret->base, &in->base);
 152     return ret;
 153 }
 154
 155 static int aes_xts_cipher(void *vctx, unsigned char *out, size_t *outl,
 156                           size_t outsize, const unsigned char *in, size_t inl)
 157 {
 158     PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
 159
 160     if (!ossl_prov_is_running()
 161             || ctx->xts.key1 == NULL
 162             || ctx->xts.key2 == NULL
 163             || !ctx->base.iv_set
 164             || out == NULL
 165             || in == NULL
 166             || inl < AES_BLOCK_SIZE)
 167         return 0;
 168
 169     /*
 170      * Impose a limit of 2^20 blocks per data unit as specified by
 171      * IEEE Std 1619-2018.  The earlier and obsolete IEEE Std 1619-2007
 172      * indicated that this was a SHOULD NOT rather than a MUST NOT.
 173      * NIST SP 800-38E mandates the same limit.
 174      */
 175     if (inl > XTS_MAX_BLOCKS_PER_DATA_UNIT * AES_BLOCK_SIZE) {
 176         ERR_raise(ERR_LIB_PROV, PROV_R_XTS_DATA_UNIT_IS_TOO_LARGE);
 177         return 0;
 178     }
 179
 180     if (ctx->stream != NULL)
 181         (*ctx->stream)(in, out, inl, ctx->xts.key1, ctx->xts.key2, ctx->base.iv);
 182     else if (CRYPTO_xts128_encrypt(&ctx->xts, ctx->base.iv, in, out, inl,
 183                                    ctx->base.enc))
 184         return 0;
 185
 186     *outl = inl;
 187     return 1;
 188 }
 189
 190 static int aes_xts_stream_update(void *vctx, unsigned char *out, size_t *outl,
 191                                  size_t outsize, const unsigned char *in,
 192                                  size_t inl)
 193 {
 194     PROV_AES_XTS_CTX *ctx = (PROV_AES_XTS_CTX *)vctx;
 195
 196     if (outsize < inl) {
 197         ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 198         return 0;
 199     }
 200
 201     if (!aes_xts_cipher(ctx, out, outl, outsize, in, inl)) {
 202         ERR_raise(ERR_LIB_PROV, PROV_R_CIPHER_OPERATION_FAILED);
 203         return 0;
 204     }
 205
 206     return 1;
 207 }
 208
 209 static int aes_xts_stream_final(void *vctx, unsigned char *out, size_t *outl,
 210                                 size_t outsize)
 211 {
 212     if (!ossl_prov_is_running())
 213         return 0;
 214     *outl = 0;
 215     return 1;
 216 }
 217
 218 static const OSSL_PARAM aes_xts_known_settable_ctx_params[] = {
 219     OSSL_PARAM_size_t(OSSL_CIPHER_PARAM_KEYLEN, NULL),
 220     OSSL_PARAM_END
 221 };
 222
 223 static const OSSL_PARAM *aes_xts_settable_ctx_params(ossl_unused void *cctx,
 224                                                      ossl_unused void *provctx)
 225 {
 226     return aes_xts_known_settable_ctx_params;
 227 }
 228
 229 static int aes_xts_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 230 {
 231     PROV_CIPHER_CTX *ctx = (PROV_CIPHER_CTX *)vctx;
 232     const OSSL_PARAM *p;
 233
 234     if (params == NULL)
 235         return 1;
 236
 237     p = OSSL_PARAM_locate_const(params, OSSL_CIPHER_PARAM_KEYLEN);
 238     if (p != NULL) {
 239         size_t keylen;
 240
 241         if (!OSSL_PARAM_get_size_t(p, &keylen)) {
 242             ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GET_PARAMETER);
 243             return 0;
 244         }
 245         /* The key length can not be modified for xts mode */
 246         if (keylen != ctx->keylen)
 247             return 0;
 248     }
 249
 250     return 1;
 251 }
 252
 253 #define IMPLEMENT_cipher(lcmode, UCMODE, kbits, flags)                         \
 254 static OSSL_FUNC_cipher_get_params_fn aes_##kbits##_##lcmode##_get_params;     \
 255 static int aes_##kbits##_##lcmode##_get_params(OSSL_PARAM params[])            \
 256 {                                                                              \
 257     return ossl_cipher_generic_get_params(params, EVP_CIPH_##UCMODE##_MODE,    \
 258                                      flags, 2 * kbits, AES_XTS_BLOCK_BITS,     \
 259                                      AES_XTS_IV_BITS);                         \
 260 }                                                                              \
 261 static OSSL_FUNC_cipher_newctx_fn aes_##kbits##_xts_newctx;                    \
 262 static void *aes_##kbits##_xts_newctx(void *provctx)                           \
 263 {                                                                              \
 264     return aes_xts_newctx(provctx, EVP_CIPH_##UCMODE##_MODE, flags, 2 * kbits, \
 265                           AES_XTS_BLOCK_BITS, AES_XTS_IV_BITS);                \
 266 }                                                                              \
 267 const OSSL_DISPATCH ossl_aes##kbits##xts_functions[] = {                       \
 268     { OSSL_FUNC_CIPHER_NEWCTX, (void (*)(void))aes_##kbits##_xts_newctx },     \
 269     { OSSL_FUNC_CIPHER_ENCRYPT_INIT, (void (*)(void))aes_xts_einit },          \
 270     { OSSL_FUNC_CIPHER_DECRYPT_INIT, (void (*)(void))aes_xts_dinit },          \
 271     { OSSL_FUNC_CIPHER_UPDATE, (void (*)(void))aes_xts_stream_update },        \
 272     { OSSL_FUNC_CIPHER_FINAL, (void (*)(void))aes_xts_stream_final },          \
 273     { OSSL_FUNC_CIPHER_CIPHER, (void (*)(void))aes_xts_cipher },               \
 274     { OSSL_FUNC_CIPHER_FREECTX, (void (*)(void))aes_xts_freectx },             \
 275     { OSSL_FUNC_CIPHER_DUPCTX, (void (*)(void))aes_xts_dupctx },               \
 276     { OSSL_FUNC_CIPHER_GET_PARAMS,                                             \
 277       (void (*)(void))aes_##kbits##_##lcmode##_get_params },                   \
 278     { OSSL_FUNC_CIPHER_GETTABLE_PARAMS,                                        \
 279       (void (*)(void))ossl_cipher_generic_gettable_params },                   \
 280     { OSSL_FUNC_CIPHER_GET_CTX_PARAMS,                                         \
 281       (void (*)(void))ossl_cipher_generic_get_ctx_params },                    \
 282     { OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS,                                    \
 283       (void (*)(void))ossl_cipher_generic_gettable_ctx_params },               \
 284     { OSSL_FUNC_CIPHER_SET_CTX_PARAMS,                                         \
 285       (void (*)(void))aes_xts_set_ctx_params },                                \
 286     { OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS,                                    \
 287      (void (*)(void))aes_xts_settable_ctx_params },                            \
 288     { 0, NULL }                                                                \
 289 }
 290
 291 IMPLEMENT_cipher(xts, XTS, 256, AES_XTS_FLAGS);
 292 IMPLEMENT_cipher(xts, XTS, 128, AES_XTS_FLAGS);