2 * Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
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
11 * See SP800-185 "Appendix A - KMAC, .... in Terms of Keccak[c]"
14 * K = Key (len(K) < 2^2040 bits)
16 * L = Output length (0 <= L < 2^2040 bits)
17 * S = Customization String Default="" (len(S) < 2^2040 bits)
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).
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).
33 * KMAC128XOF(K, X, L, S)
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).
40 * KMAC256XOF(K, X, L, S)
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).
50 #include <openssl/evp.h>
51 #include "internal/cryptlib.h"
52 #include "internal/evp_int.h"
54 #define KMAC_MAX_BLOCKSIZE ((1600 - 128*2) / 8) /* 168 */
55 #define KMAC_MIN_BLOCKSIZE ((1600 - 256*2) / 8) /* 136 */
57 /* Length encoding will be a 1 byte size + length in bits (2 bytes max) */
58 #define KMAC_MAX_ENCODED_HEADER_LEN 3
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
65 #define KMAC_MAX_CUSTOM 127
67 /* Maximum size of encoded custom string */
68 #define KMAC_MAX_CUSTOM_ENCODED (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_HEADER_LEN)
70 /* Maximum key size in bytes = 2040 / 8 */
71 #define KMAC_MAX_KEY 255
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
78 #define KMAC_MAX_KEY_ENCODED (KMAC_MAX_BLOCKSIZE * 2)
80 /* Fixed value of encode_string("KMAC") */
81 static const unsigned char kmac_string[] = {
82 0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43
86 #define KMAC_FLAG_XOF_MODE 1
88 /* typedef EVP_MAC_IMPL */
89 struct evp_mac_impl_st {
95 /* If xof_mode = 1 then we use right_encode(0) */
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];
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,
109 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
110 const unsigned char *in, int in_len,
112 static int kmac_ctrl_str(EVP_MAC_IMPL *kctx, const char *type,
116 static void kmac_free(EVP_MAC_IMPL *kctx)
119 EVP_MD_CTX_free(kctx->ctx);
120 OPENSSL_cleanse(kctx->key, kctx->key_len);
121 OPENSSL_cleanse(kctx->custom, kctx->custom_len);
126 static EVP_MAC_IMPL *kmac_new(const EVP_MD *md)
128 EVP_MAC_IMPL *kctx = NULL;
130 if ((kctx = OPENSSL_zalloc(sizeof(*kctx))) == NULL
131 || (kctx->ctx = EVP_MD_CTX_new()) == NULL) {
136 kctx->out_len = md->md_size;
140 static EVP_MAC_IMPL *kmac128_new(void)
142 return kmac_new(evp_keccak_kmac128());
145 static EVP_MAC_IMPL *kmac256_new(void)
147 return kmac_new(evp_keccak_kmac256());
150 static int kmac_copy(EVP_MAC_IMPL *gdst, EVP_MAC_IMPL *gsrc)
153 gdst->out_len = gsrc->out_len;
154 gdst->key_len = gsrc->key_len;
155 gdst->custom_len = gsrc->custom_len;
156 gdst->xof_mode = gsrc->xof_mode;
157 memcpy(gdst->key, gsrc->key, gsrc->key_len);
158 memcpy(gdst->custom, gsrc->custom, gdst->custom_len);
160 return EVP_MD_CTX_copy(gdst->ctx, gsrc->ctx);
164 * The init() assumes that any ctrl methods are set beforehand for
165 * md, key and custom. Setting the fields afterwards will have no
166 * effect on the output mac.
168 static int kmac_init(EVP_MAC_IMPL *kctx)
170 EVP_MD_CTX *ctx = kctx->ctx;
171 unsigned char out[KMAC_MAX_BLOCKSIZE];
172 int out_len, block_len;
174 /* Check key has been set */
175 if (kctx->key_len == 0) {
176 EVPerr(EVP_F_KMAC_INIT, EVP_R_NO_KEY_SET);
179 if (!EVP_DigestInit_ex(kctx->ctx, kctx->md, NULL))
182 block_len = EVP_MD_block_size(kctx->md);
184 /* Set default custom string if it is not already set */
185 if (kctx->custom_len == 0)
186 (void)kmac_ctrl_str(kctx, "custom", "");
188 return bytepad(out, &out_len, kmac_string, sizeof(kmac_string),
189 kctx->custom, kctx->custom_len, block_len)
190 && EVP_DigestUpdate(ctx, out, out_len)
191 && EVP_DigestUpdate(ctx, kctx->key, kctx->key_len);
194 static size_t kmac_size(EVP_MAC_IMPL *kctx)
196 return kctx->out_len;
199 static int kmac_update(EVP_MAC_IMPL *kctx, const unsigned char *data,
202 return EVP_DigestUpdate(kctx->ctx, data, datalen);
205 static int kmac_final(EVP_MAC_IMPL *kctx, unsigned char *out)
207 EVP_MD_CTX *ctx = kctx->ctx;
209 unsigned char encoded_outlen[KMAC_MAX_ENCODED_HEADER_LEN];
211 /* KMAC XOF mode sets the encoded length to 0 */
212 lbits = (kctx->xof_mode ? 0 : (kctx->out_len * 8));
214 return right_encode(encoded_outlen, &len, lbits)
215 && EVP_DigestUpdate(ctx, encoded_outlen, len)
216 && EVP_DigestFinalXOF(ctx, out, kctx->out_len);
220 * The following Ctrl functions can be set any time before final():
221 * - EVP_MAC_CTRL_SET_SIZE: The requested output length.
222 * - EVP_MAC_CTRL_SET_XOF: If set, this indicates that right_encoded(0) is
223 * part of the digested data, otherwise it uses
224 * right_encoded(requested output length).
226 * All other Ctrl functions should be set before init().
228 static int kmac_ctrl(EVP_MAC_IMPL *kctx, int cmd, va_list args)
230 const unsigned char *p;
235 case EVP_MAC_CTRL_SET_XOF:
236 kctx->xof_mode = va_arg(args, int);
239 case EVP_MAC_CTRL_SET_SIZE:
240 size = va_arg(args, size_t);
241 kctx->out_len = size;
244 case EVP_MAC_CTRL_SET_KEY:
245 p = va_arg(args, const unsigned char *);
246 len = va_arg(args, size_t);
247 if (len < 4 || len > KMAC_MAX_KEY) {
248 EVPerr(EVP_F_KMAC_CTRL, EVP_R_INVALID_KEY_LENGTH);
251 return kmac_bytepad_encode_key(kctx->key, &kctx->key_len, p, len,
252 EVP_MD_block_size(kctx->md));
254 case EVP_MAC_CTRL_SET_CUSTOM:
255 p = va_arg(args, const unsigned char *);
256 len = va_arg(args, size_t);
257 if (len > KMAC_MAX_CUSTOM) {
258 EVPerr(EVP_F_KMAC_CTRL, EVP_R_INVALID_CUSTOM_LENGTH);
261 return encode_string(kctx->custom, &kctx->custom_len, p, len);
268 static int kmac_ctrl_int(EVP_MAC_IMPL *kctx, int cmd, ...)
274 rv = kmac_ctrl(kctx, cmd, args);
280 static int kmac_ctrl_str_cb(void *kctx, int cmd, void *buf, size_t buflen)
282 return kmac_ctrl_int(kctx, cmd, buf, buflen);
285 static int kmac_ctrl_str(EVP_MAC_IMPL *kctx, const char *type,
291 if (strcmp(type, "outlen") == 0)
292 return kmac_ctrl_int(kctx, EVP_MAC_CTRL_SET_SIZE, (size_t)atoi(value));
293 if (strcmp(type, "xof") == 0)
294 return kmac_ctrl_int(kctx, EVP_MAC_CTRL_SET_XOF, atoi(value));
295 if (strcmp(type, "key") == 0)
296 return EVP_str2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_KEY,
298 if (strcmp(type, "hexkey") == 0)
299 return EVP_hex2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_KEY,
301 if (strcmp(type, "custom") == 0)
302 return EVP_str2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_CUSTOM,
304 if (strcmp(type, "hexcustom") == 0)
305 return EVP_hex2ctrl(kmac_ctrl_str_cb, kctx, EVP_MAC_CTRL_SET_CUSTOM,
311 * Encoding/Padding Methods.
314 /* Returns the number of bytes required to store 'bits' into a byte array */
315 static unsigned int get_encode_size(size_t bits)
317 unsigned int cnt = 0, sz = sizeof(size_t);
319 while (bits && (cnt < sz)) {
323 /* If bits is zero 1 byte is required */
330 * Convert an integer into bytes . The number of bytes is appended
331 * to the end of the buffer. Returns an array of bytes 'out' of size
334 * e.g if bits = 32, out[2] = { 0x20, 0x01 }
337 static int right_encode(unsigned char *out, int *out_len, size_t bits)
339 unsigned int len = get_encode_size(bits);
342 /* The length is constrained to a single byte: 2040/8 = 255 */
346 /* MSB's are at the start of the bytes array */
347 for (i = len - 1; i >= 0; --i) {
348 out[i] = (unsigned char)(bits & 0xFF);
351 /* Tack the length onto the end */
352 out[len] = (unsigned char)len;
354 /* The Returned length includes the tacked on byte */
360 * Encodes a string with a left encoded length added. Note that the
361 * in_len is converted to bits (*8).
363 * e.g- in="KMAC" gives out[6] = { 0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43 }
366 static int encode_string(unsigned char *out, int *out_len,
367 const unsigned char *in, int in_len)
375 len = get_encode_size(bits);
380 for (i = len; i > 0; --i) {
381 out[i] = (bits & 0xFF);
384 memcpy(out + len + 1, in, in_len);
385 *out_len = (1 + len + in_len);
391 * Returns a zero padded encoding of the inputs in1 and an optional
392 * in2 (can be NULL). The padded output must be a multiple of the blocksize 'w'.
393 * The value of w is in bytes (< 256).
395 * The returned output is:
396 * zero_padded(multiple of w, (left_encode(w) || in1 [|| in2])
398 static int bytepad(unsigned char *out, int *out_len,
399 const unsigned char *in1, int in1_len,
400 const unsigned char *in2, int in2_len, int w)
403 unsigned char *p = out;
410 memcpy(p, in1, in1_len);
413 if (in2 != NULL && in2_len > 0) {
414 memcpy(p, in2, in2_len);
417 /* Figure out the pad size (divisible by w) */
422 /* zero pad the end of the buffer */
423 memset(p, 0, sz - len);
429 * Returns out = bytepad(encode_string(in), w)
431 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
432 const unsigned char *in, int in_len,
435 unsigned char tmp[KMAC_MAX_KEY + KMAC_MAX_ENCODED_HEADER_LEN];
438 if (!encode_string(tmp, &tmp_len, in, in_len))
441 return bytepad(out, out_len, tmp, tmp_len, NULL, 0, w);
444 const EVP_MAC kmac128_meth = {
457 const EVP_MAC kmac256_meth = {