providers/implementations/macs/kmac_prov.c

   1 /*
   2  * Copyright 2018-2020 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  * See SP800-185 "Appendix A - KMAC, .... in Terms of Keccak[c]"
  12  *
  13  * Inputs are:
  14  *    K = Key                  (len(K) < 2^2040 bits)
  15  *    X = Input
  16  *    L = Output length        (0 <= L < 2^2040 bits)
  17  *    S = Customization String Default="" (len(S) < 2^2040 bits)
  18  *
  19  * KMAC128(K, X, L, S)
  20  * {
  21  *     newX = bytepad(encode_string(K), 168) ||  X || right_encode(L).
  22  *     T = bytepad(encode_string("KMAC") || encode_string(S), 168).
  23  *     return KECCAK[256](T || newX || 00, L).
  24  * }
  25  *
  26  * KMAC256(K, X, L, S)
  27  * {
  28  *     newX = bytepad(encode_string(K), 136) ||  X || right_encode(L).
  29  *     T = bytepad(encode_string("KMAC") || encode_string(S), 136).
  30  *     return KECCAK[512](T || newX || 00, L).
  31  * }
  32  *
  33  * KMAC128XOF(K, X, L, S)
  34  * {
  35  *     newX = bytepad(encode_string(K), 168) ||  X || right_encode(0).
  36  *     T = bytepad(encode_string("KMAC") || encode_string(S), 168).
  37  *     return KECCAK[256](T || newX || 00, L).
  38  * }
  39  *
  40  * KMAC256XOF(K, X, L, S)
  41  * {
  42  *     newX = bytepad(encode_string(K), 136) ||  X || right_encode(0).
  43  *     T = bytepad(encode_string("KMAC") || encode_string(S), 136).
  44  *     return KECCAK[512](T || newX || 00, L).
  45  * }
  46  *
  47  */
  48
  49 #include <stdlib.h>
  50 #include <string.h>
  51 #include <openssl/core_dispatch.h>
  52 #include <openssl/core_names.h>
  53 #include <openssl/params.h>
  54 #include <openssl/evp.h>
  55 #include <openssl/err.h>
  56
  57 #include "prov/providercommonerr.h"
  58 #include "prov/implementations.h"
  59 #include "prov/provider_ctx.h"
  60 #include "prov/provider_util.h"
  61
  62 /*
  63  * Forward declaration of everything implemented here.  This is not strictly
  64  * necessary for the compiler, but provides an assurance that the signatures
  65  * of the functions in the dispatch table are correct.
  66  */
  67 static OSSL_FUNC_mac_newctx_fn kmac128_new;
  68 static OSSL_FUNC_mac_newctx_fn kmac256_new;
  69 static OSSL_FUNC_mac_dupctx_fn kmac_dup;
  70 static OSSL_FUNC_mac_freectx_fn kmac_free;
  71 static OSSL_FUNC_mac_gettable_ctx_params_fn kmac_gettable_ctx_params;
  72 static OSSL_FUNC_mac_get_ctx_params_fn kmac_get_ctx_params;
  73 static OSSL_FUNC_mac_settable_ctx_params_fn kmac_settable_ctx_params;
  74 static OSSL_FUNC_mac_set_ctx_params_fn kmac_set_ctx_params;
  75 static OSSL_FUNC_mac_size_fn kmac_size;
  76 static OSSL_FUNC_mac_init_fn kmac_init;
  77 static OSSL_FUNC_mac_update_fn kmac_update;
  78 static OSSL_FUNC_mac_final_fn kmac_final;
  79
  80 #define KMAC_MAX_BLOCKSIZE ((1600 - 128*2) / 8) /* 168 */
  81 #define KMAC_MIN_BLOCKSIZE ((1600 - 256*2) / 8) /* 136 */
  82
  83 /* Length encoding will be  a 1 byte size + length in bits (2 bytes max) */
  84 #define KMAC_MAX_ENCODED_HEADER_LEN 3
  85
  86 /*
  87  * Custom string max size is chosen such that:
  88  *   len(encoded_string(custom) + len(kmac_encoded_string) <= KMAC_MIN_BLOCKSIZE
  89  *   i.e: (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_LEN) + 6 <= 136
  90  */
  91 #define KMAC_MAX_CUSTOM 127
  92
  93 /* Maximum size of encoded custom string */
  94 #define KMAC_MAX_CUSTOM_ENCODED (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_HEADER_LEN)
  95
  96 /* Maximum key size in bytes = 2040 / 8 */
  97 #define KMAC_MAX_KEY 255
  98
  99 /*
 100  * Maximum Encoded Key size will be padded to a multiple of the blocksize
 101  * i.e KMAC_MAX_KEY + KMAC_MAX_ENCODED_LEN = 258
 102  * Padded to a multiple of KMAC_MAX_BLOCKSIZE
 103  */
 104 #define KMAC_MAX_KEY_ENCODED (KMAC_MAX_BLOCKSIZE * 2)
 105
 106 /* Fixed value of encode_string("KMAC") */
 107 static const unsigned char kmac_string[] = {
 108     0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43
 109 };
 110
 111
 112 #define KMAC_FLAG_XOF_MODE          1
 113
 114 struct kmac_data_st {
 115     void  *provctx;
 116     EVP_MD_CTX *ctx;
 117     PROV_DIGEST digest;
 118     size_t out_len;
 119     int key_len;
 120     int custom_len;
 121     /* If xof_mode = 1 then we use right_encode(0) */
 122     int xof_mode;
 123     /* key and custom are stored in encoded form */
 124     unsigned char key[KMAC_MAX_KEY_ENCODED];
 125     unsigned char custom[KMAC_MAX_CUSTOM_ENCODED];
 126 };
 127
 128 static int encode_string(unsigned char *out, int *out_len,
 129                          const unsigned char *in, int in_len);
 130 static int right_encode(unsigned char *out, int *out_len, size_t bits);
 131 static int bytepad(unsigned char *out, int *out_len,
 132                    const unsigned char *in1, int in1_len,
 133                    const unsigned char *in2, int in2_len,
 134                    int w);
 135 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
 136                                    const unsigned char *in, int in_len,
 137                                    int w);
 138
 139 static void kmac_free(void *vmacctx)
 140 {
 141     struct kmac_data_st *kctx = vmacctx;
 142
 143     if (kctx != NULL) {
 144         EVP_MD_CTX_free(kctx->ctx);
 145         ossl_prov_digest_reset(&kctx->digest);
 146         OPENSSL_cleanse(kctx->key, kctx->key_len);
 147         OPENSSL_cleanse(kctx->custom, kctx->custom_len);
 148         OPENSSL_free(kctx);
 149     }
 150 }
 151
 152 /*
 153  * We have KMAC implemented as a hash, which we can use instead of
 154  * reimplementing the EVP functionality with direct use of
 155  * keccak_mac_init() and friends.
 156  */
 157 static struct kmac_data_st *kmac_new(void *provctx)
 158 {
 159     struct kmac_data_st *kctx;
 160
 161     if ((kctx = OPENSSL_zalloc(sizeof(*kctx))) == NULL
 162             || (kctx->ctx = EVP_MD_CTX_new()) == NULL) {
 163         kmac_free(kctx);
 164         return NULL;
 165     }
 166     kctx->provctx = provctx;
 167     return kctx;
 168 }
 169
 170 static void *kmac_fetch_new(void *provctx, const OSSL_PARAM *params)
 171 {
 172     struct kmac_data_st *kctx = kmac_new(provctx);
 173
 174     if (kctx == NULL)
 175         return 0;
 176     if (!ossl_prov_digest_load_from_params(&kctx->digest, params,
 177                                       PROV_LIBRARY_CONTEXT_OF(provctx))) {
 178         kmac_free(kctx);
 179         return 0;
 180     }
 181
 182     kctx->out_len = EVP_MD_size(ossl_prov_digest_md(&kctx->digest));
 183     return kctx;
 184 }
 185
 186 static void *kmac128_new(void *provctx)
 187 {
 188     static const OSSL_PARAM kmac128_params[] = {
 189         OSSL_PARAM_utf8_string("digest", OSSL_DIGEST_NAME_KECCAK_KMAC128,
 190                                sizeof(OSSL_DIGEST_NAME_KECCAK_KMAC128)),
 191         OSSL_PARAM_END
 192     };
 193     return kmac_fetch_new(provctx, kmac128_params);
 194 }
 195
 196 static void *kmac256_new(void *provctx)
 197 {
 198     static const OSSL_PARAM kmac256_params[] = {
 199         OSSL_PARAM_utf8_string("digest", OSSL_DIGEST_NAME_KECCAK_KMAC256,
 200                                sizeof(OSSL_DIGEST_NAME_KECCAK_KMAC256)),
 201         OSSL_PARAM_END
 202     };
 203     return kmac_fetch_new(provctx, kmac256_params);
 204 }
 205
 206 static void *kmac_dup(void *vsrc)
 207 {
 208     struct kmac_data_st *src = vsrc;
 209     struct kmac_data_st *dst = kmac_new(src->provctx);
 210
 211     if (dst == NULL)
 212         return NULL;
 213
 214     if (!EVP_MD_CTX_copy(dst->ctx, src->ctx)
 215         || !ossl_prov_digest_copy(&dst->digest, &src->digest)) {
 216         kmac_free(dst);
 217         return NULL;
 218     }
 219
 220     dst->out_len = src->out_len;
 221     dst->key_len = src->key_len;
 222     dst->custom_len = src->custom_len;
 223     dst->xof_mode = src->xof_mode;
 224     memcpy(dst->key, src->key, src->key_len);
 225     memcpy(dst->custom, src->custom, dst->custom_len);
 226
 227     return dst;
 228 }
 229
 230 /*
 231  * The init() assumes that any ctrl methods are set beforehand for
 232  * md, key and custom. Setting the fields afterwards will have no
 233  * effect on the output mac.
 234  */
 235 static int kmac_init(void *vmacctx)
 236 {
 237     struct kmac_data_st *kctx = vmacctx;
 238     EVP_MD_CTX *ctx = kctx->ctx;
 239     unsigned char out[KMAC_MAX_BLOCKSIZE];
 240     int out_len, block_len;
 241
 242
 243     /* Check key has been set */
 244     if (kctx->key_len == 0) {
 245         EVPerr(EVP_F_KMAC_INIT, EVP_R_NO_KEY_SET);
 246         return 0;
 247     }
 248     if (!EVP_DigestInit_ex(kctx->ctx, ossl_prov_digest_md(&kctx->digest),
 249                            NULL))
 250         return 0;
 251
 252     block_len = EVP_MD_block_size(ossl_prov_digest_md(&kctx->digest));
 253     if (block_len < 0)
 254         return 0;
 255
 256     /* Set default custom string if it is not already set */
 257     if (kctx->custom_len == 0) {
 258         const OSSL_PARAM params[] = {
 259             OSSL_PARAM_octet_string(OSSL_MAC_PARAM_CUSTOM, "", 0),
 260             OSSL_PARAM_END
 261         };
 262         (void)kmac_set_ctx_params(kctx, params);
 263     }
 264
 265     return bytepad(out, &out_len, kmac_string, sizeof(kmac_string),
 266                    kctx->custom, kctx->custom_len, block_len)
 267            && EVP_DigestUpdate(ctx, out, out_len)
 268            && EVP_DigestUpdate(ctx, kctx->key, kctx->key_len);
 269 }
 270
 271 static size_t kmac_size(void *vmacctx)
 272 {
 273     struct kmac_data_st *kctx = vmacctx;
 274
 275     return kctx->out_len;
 276 }
 277
 278 static int kmac_update(void *vmacctx, const unsigned char *data,
 279                        size_t datalen)
 280 {
 281     struct kmac_data_st *kctx = vmacctx;
 282
 283     return EVP_DigestUpdate(kctx->ctx, data, datalen);
 284 }
 285
 286 static int kmac_final(void *vmacctx, unsigned char *out, size_t *outl,
 287                       size_t outsize)
 288 {
 289     struct kmac_data_st *kctx = vmacctx;
 290     EVP_MD_CTX *ctx = kctx->ctx;
 291     int lbits, len;
 292     unsigned char encoded_outlen[KMAC_MAX_ENCODED_HEADER_LEN];
 293     int ok;
 294
 295     /* KMAC XOF mode sets the encoded length to 0 */
 296     lbits = (kctx->xof_mode ? 0 : (kctx->out_len * 8));
 297
 298     ok = right_encode(encoded_outlen, &len, lbits)
 299         && EVP_DigestUpdate(ctx, encoded_outlen, len)
 300         && EVP_DigestFinalXOF(ctx, out, kctx->out_len);
 301     *outl = kctx->out_len;
 302     return ok;
 303 }
 304
 305 static const OSSL_PARAM known_gettable_ctx_params[] = {
 306     OSSL_PARAM_size_t(OSSL_MAC_PARAM_SIZE, NULL),
 307     OSSL_PARAM_END
 308 };
 309 static const OSSL_PARAM *kmac_gettable_ctx_params(void *provctx)
 310 {
 311     return known_gettable_ctx_params;
 312 }
 313
 314 static int kmac_get_ctx_params(void *vmacctx, OSSL_PARAM params[])
 315 {
 316     OSSL_PARAM *p;
 317
 318     if ((p = OSSL_PARAM_locate(params, OSSL_MAC_PARAM_SIZE)) != NULL)
 319         return OSSL_PARAM_set_size_t(p, kmac_size(vmacctx));
 320
 321     return 1;
 322 }
 323
 324 static const OSSL_PARAM known_settable_ctx_params[] = {
 325     OSSL_PARAM_int(OSSL_MAC_PARAM_XOF, NULL),
 326     OSSL_PARAM_size_t(OSSL_MAC_PARAM_SIZE, NULL),
 327     OSSL_PARAM_octet_string(OSSL_MAC_PARAM_KEY, NULL, 0),
 328     OSSL_PARAM_octet_string(OSSL_MAC_PARAM_CUSTOM, NULL, 0),
 329     OSSL_PARAM_END
 330 };
 331 static const OSSL_PARAM *kmac_settable_ctx_params(void *provctx)
 332 {
 333     return known_settable_ctx_params;
 334 }
 335
 336 /*
 337  * The following params can be set any time before final():
 338  *     - "outlen" or "size":    The requested output length.
 339  *     - "xof":                 If set, this indicates that right_encoded(0)
 340  *                              is part of the digested data, otherwise it
 341  *                              uses right_encoded(requested output length).
 342  *
 343  * All other params should be set before init().
 344  */
 345 static int kmac_set_ctx_params(void *vmacctx, const OSSL_PARAM *params)
 346 {
 347     struct kmac_data_st *kctx = vmacctx;
 348     const OSSL_PARAM *p;
 349     const EVP_MD *digest = ossl_prov_digest_md(&kctx->digest);
 350
 351     if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_XOF)) != NULL
 352         && !OSSL_PARAM_get_int(p, &kctx->xof_mode))
 353         return 0;
 354     if (((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_SIZE)) != NULL)
 355         && !OSSL_PARAM_get_size_t(p, &kctx->out_len))
 356         return 0;
 357     if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_KEY)) != NULL) {
 358         if (p->data_size < 4 || p->data_size > KMAC_MAX_KEY) {
 359             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
 360             return 0;
 361         }
 362         if (!kmac_bytepad_encode_key(kctx->key, &kctx->key_len,
 363                                      p->data, p->data_size,
 364                                      EVP_MD_block_size(digest)))
 365             return 0;
 366     }
 367     if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_CUSTOM))
 368         != NULL) {
 369         if (p->data_size > KMAC_MAX_CUSTOM) {
 370             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CUSTOM_LENGTH);
 371             return 0;
 372         }
 373         if (!encode_string(kctx->custom, &kctx->custom_len,
 374                            p->data, p->data_size))
 375             return 0;
 376     }
 377     return 1;
 378 }
 379
 380 /*
 381  * Encoding/Padding Methods.
 382  */
 383
 384 /* Returns the number of bytes required to store 'bits' into a byte array */
 385 static unsigned int get_encode_size(size_t bits)
 386 {
 387     unsigned int cnt = 0, sz = sizeof(size_t);
 388
 389     while (bits && (cnt < sz)) {
 390         ++cnt;
 391         bits >>= 8;
 392     }
 393     /* If bits is zero 1 byte is required */
 394     if (cnt == 0)
 395         cnt = 1;
 396     return cnt;
 397 }
 398
 399 /*
 400  * Convert an integer into bytes . The number of bytes is appended
 401  * to the end of the buffer. Returns an array of bytes 'out' of size
 402  * *out_len.
 403  *
 404  * e.g if bits = 32, out[2] = { 0x20, 0x01 }
 405  *
 406  */
 407 static int right_encode(unsigned char *out, int *out_len, size_t bits)
 408 {
 409     unsigned int len = get_encode_size(bits);
 410     int i;
 411
 412     /* The length is constrained to a single byte: 2040/8 = 255 */
 413     if (len > 0xFF)
 414         return 0;
 415
 416     /* MSB's are at the start of the bytes array */
 417     for (i = len - 1; i >= 0; --i) {
 418         out[i] = (unsigned char)(bits & 0xFF);
 419         bits >>= 8;
 420     }
 421     /* Tack the length onto the end */
 422     out[len] = (unsigned char)len;
 423
 424     /* The Returned length includes the tacked on byte */
 425     *out_len = len + 1;
 426     return 1;
 427 }
 428
 429 /*
 430  * Encodes a string with a left encoded length added. Note that the
 431  * in_len is converted to bits (*8).
 432  *
 433  * e.g- in="KMAC" gives out[6] = { 0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43 }
 434  *                                 len   bits    K     M     A     C
 435  */
 436 static int encode_string(unsigned char *out, int *out_len,
 437                          const unsigned char *in, int in_len)
 438 {
 439     if (in == NULL) {
 440         *out_len = 0;
 441     } else {
 442         int i, bits, len;
 443
 444         bits = 8 * in_len;
 445         len = get_encode_size(bits);
 446         if (len > 0xFF)
 447             return 0;
 448
 449         out[0] = len;
 450         for (i = len; i > 0; --i) {
 451             out[i] = (bits & 0xFF);
 452             bits >>= 8;
 453         }
 454         memcpy(out + len + 1, in, in_len);
 455         *out_len = (1 + len + in_len);
 456     }
 457     return 1;
 458 }
 459
 460 /*
 461  * Returns a zero padded encoding of the inputs in1 and an optional
 462  * in2 (can be NULL). The padded output must be a multiple of the blocksize 'w'.
 463  * The value of w is in bytes (< 256).
 464  *
 465  * The returned output is:
 466  *    zero_padded(multiple of w, (left_encode(w) || in1 [|| in2])
 467  */
 468 static int bytepad(unsigned char *out, int *out_len,
 469                    const unsigned char *in1, int in1_len,
 470                    const unsigned char *in2, int in2_len, int w)
 471 {
 472     int len;
 473     unsigned char *p = out;
 474     int sz = w;
 475
 476     /* Left encoded w */
 477     *p++ = 1;
 478     *p++ = w;
 479     /* || in1 */
 480     memcpy(p, in1, in1_len);
 481     p += in1_len;
 482     /* [ || in2 ] */
 483     if (in2 != NULL && in2_len > 0) {
 484         memcpy(p, in2, in2_len);
 485         p += in2_len;
 486     }
 487     /* Figure out the pad size (divisible by w) */
 488     len = p - out;
 489     while (len > sz) {
 490         sz += w;
 491     }
 492     /* zero pad the end of the buffer */
 493     memset(p, 0, sz - len);
 494     *out_len = sz;
 495     return 1;
 496 }
 497
 498 /*
 499  * Returns out = bytepad(encode_string(in), w)
 500  */
 501 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
 502                                    const unsigned char *in, int in_len,
 503                                    int w)
 504 {
 505     unsigned char tmp[KMAC_MAX_KEY + KMAC_MAX_ENCODED_HEADER_LEN];
 506     int tmp_len;
 507
 508     if (!encode_string(tmp, &tmp_len, in, in_len))
 509         return 0;
 510
 511     return bytepad(out, out_len, tmp, tmp_len, NULL, 0, w);
 512 }
 513
 514 const OSSL_DISPATCH kmac128_functions[] = {
 515     { OSSL_FUNC_MAC_NEWCTX, (void (*)(void))kmac128_new },
 516     { OSSL_FUNC_MAC_DUPCTX, (void (*)(void))kmac_dup },
 517     { OSSL_FUNC_MAC_FREECTX, (void (*)(void))kmac_free },
 518     { OSSL_FUNC_MAC_INIT, (void (*)(void))kmac_init },
 519     { OSSL_FUNC_MAC_UPDATE, (void (*)(void))kmac_update },
 520     { OSSL_FUNC_MAC_FINAL, (void (*)(void))kmac_final },
 521     { OSSL_FUNC_MAC_GETTABLE_CTX_PARAMS,
 522       (void (*)(void))kmac_gettable_ctx_params },
 523     { OSSL_FUNC_MAC_GET_CTX_PARAMS, (void (*)(void))kmac_get_ctx_params },
 524     { OSSL_FUNC_MAC_SETTABLE_CTX_PARAMS,
 525       (void (*)(void))kmac_settable_ctx_params },
 526     { OSSL_FUNC_MAC_SET_CTX_PARAMS, (void (*)(void))kmac_set_ctx_params },
 527     { 0, NULL }
 528 };
 529
 530 const OSSL_DISPATCH kmac256_functions[] = {
 531     { OSSL_FUNC_MAC_NEWCTX, (void (*)(void))kmac256_new },
 532     { OSSL_FUNC_MAC_DUPCTX, (void (*)(void))kmac_dup },
 533     { OSSL_FUNC_MAC_FREECTX, (void (*)(void))kmac_free },
 534     { OSSL_FUNC_MAC_INIT, (void (*)(void))kmac_init },
 535     { OSSL_FUNC_MAC_UPDATE, (void (*)(void))kmac_update },
 536     { OSSL_FUNC_MAC_FINAL, (void (*)(void))kmac_final },
 537     { OSSL_FUNC_MAC_GETTABLE_CTX_PARAMS,
 538       (void (*)(void))kmac_gettable_ctx_params },
 539     { OSSL_FUNC_MAC_GET_CTX_PARAMS, (void (*)(void))kmac_get_ctx_params },
 540     { OSSL_FUNC_MAC_SETTABLE_CTX_PARAMS,
 541       (void (*)(void))kmac_settable_ctx_params },
 542     { OSSL_FUNC_MAC_SET_CTX_PARAMS, (void (*)(void))kmac_set_ctx_params },
 543     { 0, NULL }
 544 };