crypto/kmac/kmac.c

   1 /*
   2  * Copyright 2018 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 <openssl/evp.h>
  51 #include "internal/cryptlib.h"
  52 #include "internal/evp_int.h"
  53
  54 #define KMAC_MAX_BLOCKSIZE ((1600 - 128*2) / 8) /* 168 */
  55 #define KMAC_MIN_BLOCKSIZE ((1600 - 256*2) / 8) /* 136 */
  56
  57 /* Length encoding will be  a 1 byte size + length in bits (2 bytes max) */
  58 #define KMAC_MAX_ENCODED_HEADER_LEN 3
  59
  60 /*
  61  * Custom string max size is chosen such that:
  62  *   len(encoded_string(custom) + len(kmac_encoded_string) <= KMAC_MIN_BLOCKSIZE
  63  *   i.e: (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_LEN) + 6 <= 136
  64  */
  65 #define KMAC_MAX_CUSTOM 127
  66
  67 /* Maximum size of encoded custom string */
  68 #define KMAC_MAX_CUSTOM_ENCODED (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_HEADER_LEN)
  69
  70 /* Maximum key size in bytes = 2040 / 8 */
  71 #define KMAC_MAX_KEY 255
  72
  73 /*
  74  * Maximum Encoded Key size will be padded to a multiple of the blocksize
  75  * i.e KMAC_MAX_KEY + KMAC_MAX_ENCODED_LEN = 258
  76  * Padded to a multiple of KMAC_MAX_BLOCKSIZE
  77  */
  78 #define KMAC_MAX_KEY_ENCODED (KMAC_MAX_BLOCKSIZE * 2)
  79
  80 /* Fixed value of encode_string("KMAC") */
  81 static const unsigned char kmac_string[] = {
  82     0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43
  83 };
  84
  85
  86 #define KMAC_FLAG_XOF_MODE          1
  87
  88 /* typedef EVP_MAC_IMPL */
  89 struct evp_mac_impl_st {
  90     EVP_MD_CTX *ctx;
  91     const EVP_MD *md;
  92     size_t out_len;
  93     int key_len;
  94     int custom_len;
  95     /* If xof_mode = 1 then we use right_encode(0) */
  96     int xof_mode;
  97     /* key and custom are stored in encoded form */
  98     unsigned char key[KMAC_MAX_KEY_ENCODED];
  99     unsigned char custom[KMAC_MAX_CUSTOM_ENCODED];
 100 };
 101
 102 static int encode_string(unsigned char *out, int *out_len,
 103                          const unsigned char *in, int in_len);
 104 static int right_encode(unsigned char *out, int *out_len, size_t bits);
 105 static int bytepad(unsigned char *out, int *out_len,
 106                    const unsigned char *in1, int in1_len,
 107                    const unsigned char *in2, int in2_len,
 108                    int w);
 109 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
 110                                    const unsigned char *in, int in_len,
 111                                    int w);
 112 static int kmac_ctrl_str(EVP_MAC_IMPL *kctx, const char *type,
 113                          const char *value);
 114
 115
 116 static void kmac_free(EVP_MAC_IMPL *kctx)
 117 {
 118     if (kctx != NULL) {
 119         EVP_MD_CTX_free(kctx->ctx);
 120         OPENSSL_cleanse(kctx->key, kctx->key_len);
 121         OPENSSL_cleanse(kctx->custom, kctx->custom_len);
 122         OPENSSL_free(kctx);
 123     }
 124 }
 125
 126 static EVP_MAC_IMPL *kmac_new(const EVP_MD *md)
 127 {
 128     EVP_MAC_IMPL *kctx = NULL;
 129
 130     if ((kctx = OPENSSL_zalloc(sizeof(*kctx))) == NULL
 131             || (kctx->ctx = EVP_MD_CTX_new()) == NULL) {
 132         kmac_free(kctx);
 133         return NULL;
 134     }
 135     kctx->md = md;
 136     kctx->out_len = md->md_size;
 137     return kctx;
 138 }
 139
 140 static EVP_MAC_IMPL *kmac128_new(void)
 141 {
 142     return kmac_new(evp_keccak_kmac128());
 143 }
 144
 145 static EVP_MAC_IMPL *kmac256_new(void)
 146 {
 147     return kmac_new(evp_keccak_kmac256());
 148 }
 149
 150 static EVP_MAC_IMPL *kmac_dup(const EVP_MAC_IMPL *gsrc)
 151 {
 152     EVP_MAC_IMPL *gdst;
 153
 154     gdst = kmac_new(gsrc->md);
 155     if (gdst == NULL)
 156         return NULL;
 157
 158     if (!EVP_MD_CTX_copy(gdst->ctx, gsrc->ctx)) {
 159         kmac_free(gdst);
 160         return NULL;
 161     }
 162
 163     gdst->md = gsrc->md;
 164     gdst->out_len = gsrc->out_len;
 165     gdst->key_len = gsrc->key_len;
 166     gdst->custom_len = gsrc->custom_len;
 167     gdst->xof_mode = gsrc->xof_mode;
 168     memcpy(gdst->key, gsrc->key, gsrc->key_len);
 169     memcpy(gdst->custom, gsrc->custom, gdst->custom_len);
 170
 171     return gdst;
 172 }
 173
 174 /*
 175  * The init() assumes that any ctrl methods are set beforehand for
 176  * md, key and custom. Setting the fields afterwards will have no
 177  * effect on the output mac.
 178  */
 179 static int kmac_init(EVP_MAC_IMPL *kctx)
 180 {
 181     EVP_MD_CTX *ctx = kctx->ctx;
 182     unsigned char out[KMAC_MAX_BLOCKSIZE];
 183     int out_len, block_len;
 184
 185     /* Check key has been set */
 186     if (kctx->key_len == 0) {
 187         EVPerr(EVP_F_KMAC_INIT, EVP_R_NO_KEY_SET);
 188         return 0;
 189     }
 190     if (!EVP_DigestInit_ex(kctx->ctx, kctx->md, NULL))
 191         return 0;
 192
 193     block_len = EVP_MD_block_size(kctx->md);
 194
 195     /* Set default custom string if it is not already set */
 196     if (kctx->custom_len == 0)
 197         (void)kmac_ctrl_str(kctx, "custom", "");
 198
 199     return bytepad(out, &out_len, kmac_string, sizeof(kmac_string),
 200                    kctx->custom, kctx->custom_len, block_len)
 201            && EVP_DigestUpdate(ctx, out, out_len)
 202            && EVP_DigestUpdate(ctx, kctx->key, kctx->key_len);
 203 }
 204
 205 static size_t kmac_size(EVP_MAC_IMPL *kctx)
 206 {
 207     return kctx->out_len;
 208 }
 209
 210 static int kmac_update(EVP_MAC_IMPL *kctx, const unsigned char *data,
 211                        size_t datalen)
 212 {
 213     return EVP_DigestUpdate(kctx->ctx, data, datalen);
 214 }
 215
 216 static int kmac_final(EVP_MAC_IMPL *kctx, unsigned char *out)
 217 {
 218     EVP_MD_CTX *ctx = kctx->ctx;
 219     int lbits, len;
 220     unsigned char encoded_outlen[KMAC_MAX_ENCODED_HEADER_LEN];
 221
 222     /* KMAC XOF mode sets the encoded length to 0 */
 223     lbits = (kctx->xof_mode ? 0 : (kctx->out_len * 8));
 224
 225     return right_encode(encoded_outlen, &len, lbits)
 226            && EVP_DigestUpdate(ctx, encoded_outlen, len)
 227            && EVP_DigestFinalXOF(ctx, out, kctx->out_len);
 228 }
 229
 230 /*
 231  * The following Ctrl functions can be set any time before final():
 232  *     - EVP_MAC_CTRL_SET_SIZE: The requested output length.
 233  *     - EVP_MAC_CTRL_SET_XOF: If set, this indicates that right_encoded(0) is
 234  *                             part of the digested data, otherwise it uses
 235  *                             right_encoded(requested output length).
 236
 237  * All other Ctrl functions should be set before init().
 238  */
 239 static int kmac_ctrl(EVP_MAC_IMPL *kctx, int cmd, va_list args)
 240 {
 241     const unsigned char *p;
 242     size_t len;
 243     size_t size;
 244
 245     switch (cmd) {
 246     case EVP_MAC_CTRL_SET_XOF:
 247         kctx->xof_mode = va_arg(args, int);
 248         return 1;
 249
 250     case EVP_MAC_CTRL_SET_SIZE:
 251         size = va_arg(args, size_t);
 252         kctx->out_len = size;
 253         return 1;
 254
 255     case EVP_MAC_CTRL_SET_KEY:
 256         p = va_arg(args, const unsigned char *);
 257         len = va_arg(args, size_t);
 258         if (len < 4 || len > KMAC_MAX_KEY) {
 259             EVPerr(EVP_F_KMAC_CTRL, EVP_R_INVALID_KEY_LENGTH);
 260             return 0;
 261         }
 262         return kmac_bytepad_encode_key(kctx->key, &kctx->key_len, p, len,
 263                                        EVP_MD_block_size(kctx->md));
 264
 265     case EVP_MAC_CTRL_SET_CUSTOM:
 266         p = va_arg(args, const unsigned char *);
 267         len = va_arg(args, size_t);
 268         if (len > KMAC_MAX_CUSTOM) {
 269             EVPerr(EVP_F_KMAC_CTRL, EVP_R_INVALID_CUSTOM_LENGTH);
 270             return 0;
 271         }
 272         return encode_string(kctx->custom, &kctx->custom_len, p, len);
 273
 274     default:
 275         return -2;
 276     }
 277 }
 278
 279 static int kmac_ctrl_int(EVP_MAC_IMPL *kctx, int cmd, ...)
 280 {
 281     int rv;
 282     va_list args;
 283
 284     va_start(args, cmd);
 285     rv = kmac_ctrl(kctx, cmd, args);
 286     va_end(args);
 287
 288     return rv;
 289 }
 290
 291 static int kmac_ctrl_str_cb(void *kctx, int cmd, void *buf, size_t buflen)
 292 {
 293     return kmac_ctrl_int(kctx, cmd, buf, buflen);
 294 }
 295
 296 static int kmac_ctrl_str(EVP_MAC_IMPL *kctx, const char *type,
 297                          const char *value)
 298 {
 299     if (value == NULL)
 300         return 0;
 301
 302     if (strcmp(type, "outlen") == 0)
 303         return kmac_ctrl_int(kctx, EVP_MAC_CTRL_SET_SIZE, (size_t)atoi(value));
 304     if (strcmp(type, "xof") == 0)
 305         return kmac_ctrl_int(kctx, EVP_MAC_CTRL_SET_XOF, atoi(value));
 306     if (strcmp(type, "key") == 0)
 307         return EVP_str2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_KEY,
 308                             value);
 309     if (strcmp(type, "hexkey") == 0)
 310         return EVP_hex2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_KEY,
 311                             value);
 312     if (strcmp(type, "custom") == 0)
 313         return EVP_str2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_CUSTOM,
 314                             value);
 315     if (strcmp(type, "hexcustom") == 0)
 316         return EVP_hex2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_CUSTOM,
 317                             value);
 318     return -2;
 319 }
 320
 321 /*
 322  * Encoding/Padding Methods.
 323  */
 324
 325 /* Returns the number of bytes required to store 'bits' into a byte array */
 326 static unsigned int get_encode_size(size_t bits)
 327 {
 328     unsigned int cnt = 0, sz = sizeof(size_t);
 329
 330     while (bits && (cnt < sz)) {
 331         ++cnt;
 332         bits >>= 8;
 333     }
 334     /* If bits is zero 1 byte is required */
 335     if (cnt == 0)
 336         cnt = 1;
 337     return cnt;
 338 }
 339
 340 /*
 341  * Convert an integer into bytes . The number of bytes is appended
 342  * to the end of the buffer. Returns an array of bytes 'out' of size
 343  * *out_len.
 344  *
 345  * e.g if bits = 32, out[2] = { 0x20, 0x01 }
 346  *
 347  */
 348 static int right_encode(unsigned char *out, int *out_len, size_t bits)
 349 {
 350     unsigned int len = get_encode_size(bits);
 351     int i;
 352
 353     /* The length is constrained to a single byte: 2040/8 = 255 */
 354     if (len > 0xFF)
 355         return 0;
 356
 357     /* MSB's are at the start of the bytes array */
 358     for (i = len - 1; i >= 0; --i) {
 359         out[i] = (unsigned char)(bits & 0xFF);
 360         bits >>= 8;
 361     }
 362     /* Tack the length onto the end */
 363     out[len] = (unsigned char)len;
 364
 365     /* The Returned length includes the tacked on byte */
 366     *out_len = len + 1;
 367     return 1;
 368 }
 369
 370 /*
 371  * Encodes a string with a left encoded length added. Note that the
 372  * in_len is converted to bits (*8).
 373  *
 374  * e.g- in="KMAC" gives out[6] = { 0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43 }
 375  *                                 len   bits    K     M     A     C
 376  */
 377 static int encode_string(unsigned char *out, int *out_len,
 378                          const unsigned char *in, int in_len)
 379 {
 380     if (in == NULL) {
 381         *out_len = 0;
 382     } else {
 383         int i, bits, len;
 384
 385         bits = 8 * in_len;
 386         len = get_encode_size(bits);
 387         if (len > 0xFF)
 388             return 0;
 389
 390         out[0] = len;
 391         for (i = len; i > 0; --i) {
 392             out[i] = (bits & 0xFF);
 393             bits >>= 8;
 394         }
 395         memcpy(out + len + 1, in, in_len);
 396         *out_len = (1 + len + in_len);
 397     }
 398     return 1;
 399 }
 400
 401 /*
 402  * Returns a zero padded encoding of the inputs in1 and an optional
 403  * in2 (can be NULL). The padded output must be a multiple of the blocksize 'w'.
 404  * The value of w is in bytes (< 256).
 405  *
 406  * The returned output is:
 407  *    zero_padded(multiple of w, (left_encode(w) || in1 [|| in2])
 408  */
 409 static int bytepad(unsigned char *out, int *out_len,
 410                    const unsigned char *in1, int in1_len,
 411                    const unsigned char *in2, int in2_len, int w)
 412 {
 413     int len;
 414     unsigned char *p = out;
 415     int sz = w;
 416
 417     /* Left encoded w */
 418     *p++ = 1;
 419     *p++ = w;
 420     /* || in1 */
 421     memcpy(p, in1, in1_len);
 422     p += in1_len;
 423     /* [ || in2 ] */
 424     if (in2 != NULL && in2_len > 0) {
 425         memcpy(p, in2, in2_len);
 426         p += in2_len;
 427     }
 428     /* Figure out the pad size (divisible by w) */
 429     len = p - out;
 430     while (len > sz) {
 431         sz += w;
 432     }
 433     /* zero pad the end of the buffer */
 434     memset(p, 0, sz - len);
 435     *out_len = sz;
 436     return 1;
 437 }
 438
 439 /*
 440  * Returns out = bytepad(encode_string(in), w)
 441  */
 442 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
 443                                    const unsigned char *in, int in_len,
 444                                    int w)
 445 {
 446     unsigned char tmp[KMAC_MAX_KEY + KMAC_MAX_ENCODED_HEADER_LEN];
 447     int tmp_len;
 448
 449     if (!encode_string(tmp, &tmp_len, in, in_len))
 450         return 0;
 451
 452     return bytepad(out, out_len, tmp, tmp_len, NULL, 0, w);
 453 }
 454
 455 const EVP_MAC kmac128_meth = {
 456     EVP_MAC_KMAC128,
 457     kmac128_new,
 458     kmac_dup,
 459     kmac_free,
 460     kmac_size,
 461     kmac_init,
 462     kmac_update,
 463     kmac_final,
 464     kmac_ctrl,
 465     kmac_ctrl_str
 466 };
 467
 468 const EVP_MAC kmac256_meth = {
 469     EVP_MAC_KMAC256,
 470     kmac256_new,
 471     kmac_dup,
 472     kmac_free,
 473     kmac_size,
 474     kmac_init,
 475     kmac_update,
 476     kmac_final,
 477     kmac_ctrl,
 478     kmac_ctrl_str
 479 };
 480