118 lines
3.9 KiB
C
118 lines
3.9 KiB
C
/* ec_dsa.c - TinyCrypt implementation of EC-DSA */
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/*
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* Copyright (C) 2015 by Intel Corporation, All Rights Reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* - Neither the name of Intel Corporation nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <tinycrypt/constants.h>
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#include <tinycrypt/ecc.h>
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extern uint32_t curve_n[NUM_ECC_DIGITS];
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extern EccPoint curve_G;
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extern uint32_t curve_nb[NUM_ECC_DIGITS + 1];
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int32_t ecdsa_sign(uint32_t r[NUM_ECC_DIGITS], uint32_t s[NUM_ECC_DIGITS],
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uint32_t p_privateKey[NUM_ECC_DIGITS], uint32_t p_random[NUM_ECC_DIGITS],
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uint32_t p_hash[NUM_ECC_DIGITS])
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{
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uint32_t k[NUM_ECC_DIGITS], tmp[NUM_ECC_DIGITS];
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EccPoint p_point;
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EccPointJacobi P;
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if (vli_isZero(p_random)) {
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return TC_CRYPTO_FAIL; /* The random number must not be 0. */
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}
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vli_set(k, p_random);
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vli_sub(tmp, k, curve_n, NUM_ECC_DIGITS);
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vli_cond_set(k, k, tmp, vli_cmp(curve_n, k, NUM_ECC_DIGITS) == 1);
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/* tmp = k * G */
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EccPoint_mult(&P, &curve_G, k);
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EccPoint_toAffine(&p_point, &P);
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/* r = x1 (mod n) */
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vli_set(r, p_point.x);
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if (vli_cmp(curve_n, r, NUM_ECC_DIGITS) != 1) {
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vli_sub(r, r, curve_n, NUM_ECC_DIGITS);
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}
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if (vli_isZero(r)) {
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return TC_CRYPTO_FAIL; /* If r == 0, fail (need a different random number). */
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}
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vli_modMult(s, r, p_privateKey, curve_n, curve_nb); /* s = r*d */
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vli_modAdd(s, p_hash, s, curve_n); /* s = e + r*d */
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vli_modInv(k, k, curve_n, curve_nb); /* k = 1 / k */
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vli_modMult(s, s, k, curve_n, curve_nb); /* s = (e + r*d) / k */
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return TC_CRYPTO_SUCCESS;
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}
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int32_t ecdsa_verify(EccPoint *p_publicKey, uint32_t p_hash[NUM_ECC_DIGITS],
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uint32_t r[NUM_ECC_DIGITS], uint32_t s[NUM_ECC_DIGITS])
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{
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uint32_t u1[NUM_ECC_DIGITS], u2[NUM_ECC_DIGITS];
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uint32_t z[NUM_ECC_DIGITS];
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EccPointJacobi P, R;
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EccPoint p_point;
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if (vli_isZero(r) || vli_isZero(s)) {
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return TC_CRYPTO_FAIL; /* r, s must not be 0. */
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}
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if ((vli_cmp(curve_n, r, NUM_ECC_DIGITS) != 1) ||
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(vli_cmp(curve_n, s, NUM_ECC_DIGITS) != 1)) {
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return TC_CRYPTO_FAIL; /* r, s must be < n. */
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}
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/* Calculate u1 and u2. */
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vli_modInv(z, s, curve_n, curve_nb); /* Z = s^-1 */
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vli_modMult(u1, p_hash, z, curve_n, curve_nb); /* u1 = e/s */
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vli_modMult(u2, r, z, curve_n, curve_nb); /* u2 = r/s */
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/* calculate P = u1*G + u2*Q */
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EccPoint_mult(&P, &curve_G, u1);
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EccPoint_mult(&R, p_publicKey, u2);
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EccPoint_add(&P, &R);
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EccPoint_toAffine(&p_point, &P);
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/* Accept only if P.x == r. */
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vli_cond_set(
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p_point.x,
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p_point.x,
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z,
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vli_sub(z, p_point.x, curve_n, NUM_ECC_DIGITS));
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return (vli_cmp(p_point.x, r, NUM_ECC_DIGITS) == 0);
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}
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