providers/common/ciphers/aes.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 #include <string.h>
  11 #include <openssl/crypto.h>
  12 #include <openssl/core_numbers.h>
  13 #include <openssl/core_names.h>
  14 #include <openssl/evp.h>
  15 #include <openssl/params.h>
  16 #include <openssl/rand.h>
  17 #include "internal/cryptlib.h"
  18 #include "internal/provider_algs.h"
  19 #include "ciphers_locl.h"
  20 #include "internal/providercommonerr.h"
  21
  22 static OSSL_OP_cipher_encrypt_init_fn aes_einit;
  23 static OSSL_OP_cipher_decrypt_init_fn aes_dinit;
  24 static OSSL_OP_cipher_update_fn aes_block_update;
  25 static OSSL_OP_cipher_final_fn aes_block_final;
  26 static OSSL_OP_cipher_update_fn aes_stream_update;
  27 static OSSL_OP_cipher_final_fn aes_stream_final;
  28 static OSSL_OP_cipher_cipher_fn aes_cipher;
  29 static OSSL_OP_cipher_freectx_fn aes_freectx;
  30 static OSSL_OP_cipher_dupctx_fn aes_dupctx;
  31 static OSSL_OP_cipher_ctx_get_params_fn aes_ctx_get_params;
  32 static OSSL_OP_cipher_ctx_set_params_fn aes_ctx_set_params;
  33
  34 static int PROV_AES_KEY_generic_init(PROV_AES_KEY *ctx,
  35                                       const unsigned char *iv,
  36                                       size_t ivlen,
  37                                       int enc)
  38 {
  39     if (iv != NULL && ctx->mode != EVP_CIPH_ECB_MODE) {
  40         if (ivlen != AES_BLOCK_SIZE) {
  41             PROVerr(PROV_F_PROV_AES_KEY_GENERIC_INIT, ERR_R_INTERNAL_ERROR);
  42             return 0;
  43         }
  44         memcpy(ctx->iv, iv, AES_BLOCK_SIZE);
  45     }
  46     ctx->enc = enc;
  47
  48     return 1;
  49 }
  50
  51 static int aes_einit(void *vctx, const unsigned char *key, size_t keylen,
  52                            const unsigned char *iv, size_t ivlen)
  53 {
  54     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
  55
  56     if (!PROV_AES_KEY_generic_init(ctx, iv, ivlen, 1)) {
  57         /* PROVerr already called */
  58         return 0;
  59     }
  60     if (key != NULL) {
  61         if (keylen != ctx->keylen) {
  62             PROVerr(PROV_F_AES_EINIT, PROV_R_INVALID_KEYLEN);
  63             return 0;
  64         }
  65         return ctx->ciph->init(ctx, key, ctx->keylen);
  66     }
  67
  68     return 1;
  69 }
  70
  71 static int aes_dinit(void *vctx, const unsigned char *key, size_t keylen,
  72                      const unsigned char *iv, size_t ivlen)
  73 {
  74     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
  75
  76     if (!PROV_AES_KEY_generic_init(ctx, iv, ivlen, 0)) {
  77         /* PROVerr already called */
  78         return 0;
  79     }
  80     if (key != NULL) {
  81         if (keylen != ctx->keylen) {
  82             PROVerr(PROV_F_AES_DINIT, PROV_R_INVALID_KEYLEN);
  83             return 0;
  84         }
  85         return ctx->ciph->init(ctx, key, ctx->keylen);
  86     }
  87
  88     return 1;
  89 }
  90
  91 static int aes_block_update(void *vctx, unsigned char *out, size_t *outl,
  92                             size_t outsize, const unsigned char *in, size_t inl)
  93 {
  94     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
  95     size_t nextblocks = fillblock(ctx->buf, &ctx->bufsz, AES_BLOCK_SIZE, &in,
  96                                   &inl);
  97     size_t outlint = 0;
  98
  99     /*
 100      * If we're decrypting and we end an update on a block boundary we hold
 101      * the last block back in case this is the last update call and the last
 102      * block is padded.
 103      */
 104     if (ctx->bufsz == AES_BLOCK_SIZE
 105             && (ctx->enc || inl > 0 || !ctx->pad)) {
 106         if (outsize < AES_BLOCK_SIZE) {
 107             PROVerr(PROV_F_AES_BLOCK_UPDATE, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 108             return 0;
 109         }
 110         if (!ctx->ciph->cipher(ctx, out, ctx->buf, AES_BLOCK_SIZE)) {
 111             PROVerr(PROV_F_AES_BLOCK_UPDATE, PROV_R_CIPHER_OPERATION_FAILED);
 112             return 0;
 113         }
 114         ctx->bufsz = 0;
 115         outlint = AES_BLOCK_SIZE;
 116         out += AES_BLOCK_SIZE;
 117     }
 118     if (nextblocks > 0) {
 119         if (!ctx->enc && ctx->pad && nextblocks == inl) {
 120             if (!ossl_assert(inl >= AES_BLOCK_SIZE)) {
 121                 PROVerr(PROV_F_AES_BLOCK_UPDATE, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 122                 return 0;
 123             }
 124             nextblocks -= AES_BLOCK_SIZE;
 125         }
 126         outlint += nextblocks;
 127         if (outsize < outlint) {
 128             PROVerr(PROV_F_AES_BLOCK_UPDATE, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 129             return 0;
 130         }
 131         if (!ctx->ciph->cipher(ctx, out, in, nextblocks)) {
 132             PROVerr(PROV_F_AES_BLOCK_UPDATE, PROV_R_CIPHER_OPERATION_FAILED);
 133             return 0;
 134         }
 135         in += nextblocks;
 136         inl -= nextblocks;
 137     }
 138     if (!trailingdata(ctx->buf, &ctx->bufsz, AES_BLOCK_SIZE, &in, &inl)) {
 139         /* PROVerr already called */
 140         return 0;
 141     }
 142
 143     *outl = outlint;
 144     return inl == 0;
 145 }
 146
 147 static int aes_block_final(void *vctx, unsigned char *out, size_t *outl,
 148                            size_t outsize)
 149 {
 150     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
 151
 152     if (ctx->enc) {
 153         if (ctx->pad) {
 154             padblock(ctx->buf, &ctx->bufsz, AES_BLOCK_SIZE);
 155         } else if (ctx->bufsz == 0) {
 156             *outl = 0;
 157             return 1;
 158         } else if (ctx->bufsz != AES_BLOCK_SIZE) {
 159             PROVerr(PROV_F_AES_BLOCK_FINAL, PROV_R_WRONG_FINAL_BLOCK_LENGTH);
 160             return 0;
 161         }
 162
 163         if (outsize < AES_BLOCK_SIZE) {
 164             PROVerr(PROV_F_AES_BLOCK_FINAL, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 165             return 0;
 166         }
 167         if (!ctx->ciph->cipher(ctx, out, ctx->buf, AES_BLOCK_SIZE)) {
 168             PROVerr(PROV_F_AES_BLOCK_FINAL, PROV_R_CIPHER_OPERATION_FAILED);
 169             return 0;
 170         }
 171         ctx->bufsz = 0;
 172         *outl = AES_BLOCK_SIZE;
 173         return 1;
 174     }
 175
 176     /* Decrypting */
 177     if (ctx->bufsz != AES_BLOCK_SIZE) {
 178         if (ctx->bufsz == 0 && !ctx->pad) {
 179             *outl = 0;
 180             return 1;
 181         }
 182         PROVerr(PROV_F_AES_BLOCK_FINAL, PROV_R_WRONG_FINAL_BLOCK_LENGTH);
 183         return 0;
 184     }
 185
 186     if (!ctx->ciph->cipher(ctx, ctx->buf, ctx->buf, AES_BLOCK_SIZE)) {
 187         PROVerr(PROV_F_AES_BLOCK_FINAL, PROV_R_CIPHER_OPERATION_FAILED);
 188         return 0;
 189     }
 190
 191     if (ctx->pad && !unpadblock(ctx->buf, &ctx->bufsz, AES_BLOCK_SIZE)) {
 192         /* PROVerr already called */
 193         return 0;
 194     }
 195
 196     if (outsize < ctx->bufsz) {
 197         PROVerr(PROV_F_AES_BLOCK_FINAL, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 198         return 0;
 199     }
 200     memcpy(out, ctx->buf, ctx->bufsz);
 201     *outl = ctx->bufsz;
 202     ctx->bufsz = 0;
 203     return 1;
 204 }
 205
 206 static int aes_stream_update(void *vctx, unsigned char *out, size_t *outl,
 207                              size_t outsize, const unsigned char *in,
 208                              size_t inl)
 209 {
 210     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
 211
 212     if (outsize < inl) {
 213         PROVerr(PROV_F_AES_STREAM_UPDATE, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 214         return 0;
 215     }
 216
 217     if (!ctx->ciph->cipher(ctx, out, in, inl)) {
 218         PROVerr(PROV_F_AES_STREAM_UPDATE, PROV_R_CIPHER_OPERATION_FAILED);
 219         return 0;
 220     }
 221
 222     *outl = inl;
 223     return 1;
 224 }
 225 static int aes_stream_final(void *vctx, unsigned char *out, size_t *outl,
 226                             size_t outsize)
 227 {
 228     *outl = 0;
 229     return 1;
 230 }
 231
 232 static int aes_cipher(void *vctx,
 233                       unsigned char *out, size_t *outl, size_t outsize,
 234                       const unsigned char *in, size_t inl)
 235 {
 236     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
 237
 238     if (outsize < inl) {
 239         PROVerr(PROV_F_AES_CIPHER, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
 240         return 0;
 241     }
 242
 243     if (!ctx->ciph->cipher(ctx, out, in, inl)) {
 244         PROVerr(PROV_F_AES_CIPHER, PROV_R_CIPHER_OPERATION_FAILED);
 245         return 0;
 246     }
 247
 248     *outl = inl;
 249     return 1;
 250 }
 251
 252 static void *aes_new_ctx(void *provctx, size_t mode, size_t kbits,
 253                          const PROV_AES_CIPHER *ciph)
 254 {
 255     PROV_AES_KEY *ctx = OPENSSL_zalloc(sizeof(*ctx));
 256
 257     ctx->pad = 1;
 258     ctx->keylen = kbits / 8;
 259     ctx->ciph = ciph;
 260     ctx->mode = mode;
 261     return ctx;
 262 }
 263
 264 int aes_get_params(OSSL_PARAM params[], int md, unsigned long flags,
 265                    int kbits, int blkbits, int ivbits)
 266 {
 267     OSSL_PARAM *p;
 268
 269     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_MODE);
 270     if (p != NULL) {
 271         if (!OSSL_PARAM_set_int(p, md))
 272             return 0;
 273     }
 274     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_FLAGS);
 275     if (p != NULL) {
 276         if (!OSSL_PARAM_set_ulong(p, flags))
 277             return 0;
 278     }
 279     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_KEYLEN);
 280     if (p != NULL) {
 281         if (!OSSL_PARAM_set_int(p, kbits / 8))
 282             return 0;
 283     }
 284     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_BLOCK_SIZE);
 285     if (p != NULL) {
 286         if (!OSSL_PARAM_set_int(p, blkbits / 8))
 287             return 0;
 288     }
 289     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_IVLEN);
 290     if (p != NULL) {
 291         if (!OSSL_PARAM_set_int(p, ivbits / 8))
 292             return 0;
 293     }
 294     return 1;
 295 }
 296
 297 #define IMPLEMENT_cipher(lcmode, UCMODE, flags, kbits, blkbits, ivbits)        \
 298     static OSSL_OP_cipher_get_params_fn aes_##kbits##_##lcmode##_get_params;   \
 299     static int aes_##kbits##_##lcmode##_get_params(OSSL_PARAM params[])        \
 300     {                                                                          \
 301         return aes_get_params(params, EVP_CIPH_##UCMODE##_MODE, flags, kbits,  \
 302                               blkbits, ivbits);                                \
 303     }                                                                          \
 304     static OSSL_OP_cipher_newctx_fn aes_##kbits##_##lcmode##_newctx;           \
 305     static void *aes_##kbits##_##lcmode##_newctx(void *provctx)                \
 306     {                                                                          \
 307         return aes_new_ctx(provctx, EVP_CIPH_##UCMODE##_MODE, kbits,           \
 308                            PROV_AES_CIPHER_##lcmode(kbits / 8));               \
 309     }
 310
 311 /* ECB */
 312 IMPLEMENT_cipher(ecb, ECB, 0, 256, 128, 0)
 313 IMPLEMENT_cipher(ecb, ECB, 0, 192, 128, 0)
 314 IMPLEMENT_cipher(ecb, ECB, 0, 128, 128, 0)
 315
 316 /* CBC */
 317 IMPLEMENT_cipher(cbc, CBC, 0, 256, 128, 128)
 318 IMPLEMENT_cipher(cbc, CBC, 0, 192, 128, 128)
 319 IMPLEMENT_cipher(cbc, CBC, 0, 128, 128, 128)
 320
 321 /* OFB */
 322 IMPLEMENT_cipher(ofb, OFB, 0, 256, 8, 128)
 323 IMPLEMENT_cipher(ofb, OFB, 0, 192, 8, 128)
 324 IMPLEMENT_cipher(ofb, OFB, 0, 128, 8, 128)
 325
 326 /* CFB */
 327 IMPLEMENT_cipher(cfb, CFB, 0, 256, 8, 128)
 328 IMPLEMENT_cipher(cfb, CFB, 0, 192, 8, 128)
 329 IMPLEMENT_cipher(cfb, CFB, 0, 128, 8, 128)
 330 IMPLEMENT_cipher(cfb1, CFB, 0, 256, 8, 128)
 331 IMPLEMENT_cipher(cfb1, CFB, 0, 192, 8, 128)
 332 IMPLEMENT_cipher(cfb1, CFB, 0, 128, 8, 128)
 333 IMPLEMENT_cipher(cfb8, CFB, 0, 256, 8, 128)
 334 IMPLEMENT_cipher(cfb8, CFB, 0, 192, 8, 128)
 335 IMPLEMENT_cipher(cfb8, CFB, 0, 128, 8, 128)
 336
 337 /* CTR */
 338 IMPLEMENT_cipher(ctr, CTR, 0, 256, 8, 128)
 339 IMPLEMENT_cipher(ctr, CTR, 0, 192, 8, 128)
 340 IMPLEMENT_cipher(ctr, CTR, 0, 128, 8, 128)
 341
 342 static void aes_freectx(void *vctx)
 343 {
 344     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
 345
 346     OPENSSL_clear_free(ctx,  sizeof(*ctx));
 347 }
 348
 349 static void *aes_dupctx(void *ctx)
 350 {
 351     PROV_AES_KEY *in = (PROV_AES_KEY *)ctx;
 352     PROV_AES_KEY *ret = OPENSSL_malloc(sizeof(*ret));
 353
 354     if (ret == NULL) {
 355         PROVerr(PROV_F_AES_DUPCTX, ERR_R_MALLOC_FAILURE);
 356         return NULL;
 357     }
 358     *ret = *in;
 359
 360     return ret;
 361 }
 362
 363 static int aes_ctx_get_params(void *vctx, OSSL_PARAM params[])
 364 {
 365     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
 366     OSSL_PARAM *p;
 367
 368     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_IVLEN);
 369     if (p != NULL) {
 370         if (!OSSL_PARAM_set_int(p, AES_BLOCK_SIZE))
 371             return 0;
 372     }
 373     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_PADDING);
 374     if (p != NULL && !OSSL_PARAM_set_int(p, ctx->pad)) {
 375         PROVerr(PROV_F_AES_CTX_GET_PARAMS, PROV_R_FAILED_TO_SET_PARAMETER);
 376         return 0;
 377     }
 378     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_IV);
 379     if (p != NULL
 380         && !OSSL_PARAM_set_octet_ptr(p, &ctx->iv, AES_BLOCK_SIZE)
 381         && !OSSL_PARAM_set_octet_string(p, &ctx->iv, AES_BLOCK_SIZE)) {
 382         PROVerr(PROV_F_AES_CTX_GET_PARAMS,
 383                 PROV_R_FAILED_TO_SET_PARAMETER);
 384         return 0;
 385     }
 386     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_NUM);
 387     if (p != NULL && !OSSL_PARAM_set_size_t(p, ctx->num)) {
 388         PROVerr(PROV_F_AES_CTX_GET_PARAMS,
 389                 PROV_R_FAILED_TO_SET_PARAMETER);
 390         return 0;
 391     }
 392     p = OSSL_PARAM_locate(params, OSSL_CIPHER_PARAM_KEYLEN);
 393     if (p != NULL && !OSSL_PARAM_set_int(p, ctx->keylen)) {
 394         PROVerr(PROV_F_AES_CTX_GET_PARAMS,
 395                 PROV_R_FAILED_TO_SET_PARAMETER);
 396         return 0;
 397     }
 398
 399     return 1;
 400 }
 401
 402 static int aes_ctx_set_params(void *vctx, const OSSL_PARAM params[])
 403 {
 404     PROV_AES_KEY *ctx = (PROV_AES_KEY *)vctx;
 405     const OSSL_PARAM *p;
 406
 407     p = OSSL_PARAM_locate_const(params, OSSL_CIPHER_PARAM_PADDING);
 408     if (p != NULL) {
 409         int pad;
 410
 411         if (!OSSL_PARAM_get_int(p, &pad)) {
 412             PROVerr(PROV_F_AES_CTX_SET_PARAMS,
 413                     PROV_R_FAILED_TO_GET_PARAMETER);
 414             return 0;
 415         }
 416         ctx->pad = pad ? 1 : 0;
 417     }
 418     p = OSSL_PARAM_locate_const(params, OSSL_CIPHER_PARAM_NUM);
 419     if (p != NULL) {
 420         int num;
 421
 422         if (!OSSL_PARAM_get_int(p, &num)) {
 423             PROVerr(PROV_F_AES_CTX_SET_PARAMS,
 424                     PROV_R_FAILED_TO_GET_PARAMETER);
 425             return 0;
 426         }
 427         ctx->num = num;
 428     }
 429     p = OSSL_PARAM_locate_const(params, OSSL_CIPHER_PARAM_KEYLEN);
 430     if (p != NULL) {
 431         int keylen;
 432
 433         if (!OSSL_PARAM_get_int(p, &keylen)) {
 434             PROVerr(PROV_F_AES_CTX_SET_PARAMS,
 435                     PROV_R_FAILED_TO_GET_PARAMETER);
 436             return 0;
 437         }
 438         ctx->keylen = keylen;
 439     }
 440     return 1;
 441 }
 442
 443 #define IMPLEMENT_block_funcs(mode, kbits) \
 444     const OSSL_DISPATCH aes##kbits##mode##_functions[] = { \
 445         { OSSL_FUNC_CIPHER_NEWCTX, (void (*)(void))aes_##kbits##_##mode##_newctx }, \
 446         { OSSL_FUNC_CIPHER_ENCRYPT_INIT, (void (*)(void))aes_einit }, \
 447         { OSSL_FUNC_CIPHER_DECRYPT_INIT, (void (*)(void))aes_dinit }, \
 448         { OSSL_FUNC_CIPHER_UPDATE, (void (*)(void))aes_block_update }, \
 449         { OSSL_FUNC_CIPHER_FINAL, (void (*)(void))aes_block_final }, \
 450         { OSSL_FUNC_CIPHER_CIPHER, (void (*)(void))aes_cipher }, \
 451         { OSSL_FUNC_CIPHER_FREECTX, (void (*)(void))aes_freectx }, \
 452         { OSSL_FUNC_CIPHER_DUPCTX, (void (*)(void))aes_dupctx }, \
 453         { OSSL_FUNC_CIPHER_GET_PARAMS, (void (*)(void))aes_##kbits##_##mode##_get_params }, \
 454         { OSSL_FUNC_CIPHER_CTX_GET_PARAMS, (void (*)(void))aes_ctx_get_params }, \
 455         { OSSL_FUNC_CIPHER_CTX_SET_PARAMS, (void (*)(void))aes_ctx_set_params }, \
 456         { 0, NULL } \
 457     };
 458
 459 #define IMPLEMENT_stream_funcs(mode, kbits) \
 460     const OSSL_DISPATCH aes##kbits##mode##_functions[] = { \
 461         { OSSL_FUNC_CIPHER_NEWCTX, (void (*)(void))aes_##kbits##_##mode##_newctx }, \
 462         { OSSL_FUNC_CIPHER_ENCRYPT_INIT, (void (*)(void))aes_einit }, \
 463         { OSSL_FUNC_CIPHER_DECRYPT_INIT, (void (*)(void))aes_dinit }, \
 464         { OSSL_FUNC_CIPHER_UPDATE, (void (*)(void))aes_stream_update }, \
 465         { OSSL_FUNC_CIPHER_FINAL, (void (*)(void))aes_stream_final }, \
 466         { OSSL_FUNC_CIPHER_CIPHER, (void (*)(void))aes_cipher }, \
 467         { OSSL_FUNC_CIPHER_FREECTX, (void (*)(void))aes_freectx }, \
 468         { OSSL_FUNC_CIPHER_DUPCTX, (void (*)(void))aes_dupctx }, \
 469         { OSSL_FUNC_CIPHER_GET_PARAMS, (void (*)(void))aes_##kbits##_##mode##_get_params }, \
 470         { OSSL_FUNC_CIPHER_CTX_GET_PARAMS, (void (*)(void))aes_ctx_get_params }, \
 471         { OSSL_FUNC_CIPHER_CTX_SET_PARAMS, (void (*)(void))aes_ctx_set_params }, \
 472         { 0, NULL } \
 473     };
 474
 475 /* ECB */
 476 IMPLEMENT_block_funcs(ecb, 256)
 477 IMPLEMENT_block_funcs(ecb, 192)
 478 IMPLEMENT_block_funcs(ecb, 128)
 479
 480 /* CBC */
 481 IMPLEMENT_block_funcs(cbc, 256)
 482 IMPLEMENT_block_funcs(cbc, 192)
 483 IMPLEMENT_block_funcs(cbc, 128)
 484
 485 /* OFB */
 486 IMPLEMENT_stream_funcs(ofb, 256)
 487 IMPLEMENT_stream_funcs(ofb, 192)
 488 IMPLEMENT_stream_funcs(ofb, 128)
 489
 490 /* CFB */
 491 IMPLEMENT_stream_funcs(cfb, 256)
 492 IMPLEMENT_stream_funcs(cfb, 192)
 493 IMPLEMENT_stream_funcs(cfb, 128)
 494 IMPLEMENT_stream_funcs(cfb1, 256)
 495 IMPLEMENT_stream_funcs(cfb1, 192)
 496 IMPLEMENT_stream_funcs(cfb1, 128)
 497 IMPLEMENT_stream_funcs(cfb8, 256)
 498 IMPLEMENT_stream_funcs(cfb8, 192)
 499 IMPLEMENT_stream_funcs(cfb8, 128)
 500
 501 /* CTR */
 502 IMPLEMENT_stream_funcs(ctr, 256)
 503 IMPLEMENT_stream_funcs(ctr, 192)
 504 IMPLEMENT_stream_funcs(ctr, 128)