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crypto/secp256k1: update to github.com/bitcoin-core/secp256k1 @ 9d560f9 (#3544)

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- Use defined constants instead of hard-coding their integer value.
- Allocate secp256k1 structs on the C stack instead of converting []byte
- Remove dead code
This commit is contained in:
Felix Lange
2017-01-12 21:29:11 +01:00
committed by GitHub
parent 93077c98e4
commit e0ceeab0d1
79 changed files with 8242 additions and 2011 deletions
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229
crypto/secp256k1/libsecp256k1/src/ecdsa_impl.h
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@@ -1,5 +1,5 @@
/**********************************************************************
* Copyright (c) 2013, 2014 Pieter Wuille *
* Copyright (c) 2013-2015 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
@@ -46,66 +46,133 @@ static const secp256k1_fe secp256k1_ecdsa_const_p_minus_order = SECP256K1_FE_CON
0, 0, 0, 1, 0x45512319UL, 0x50B75FC4UL, 0x402DA172UL, 0x2FC9BAEEUL
);
static int secp256k1_der_read_len(const unsigned char **sigp, const unsigned char *sigend) {
int lenleft, b1;
size_t ret = 0;
if (*sigp >= sigend) {
return -1;
}
b1 = *((*sigp)++);
if (b1 == 0xFF) {
/* X.690-0207 8.1.3.5.c the value 0xFF shall not be used. */
return -1;
}
if ((b1 & 0x80) == 0) {
/* X.690-0207 8.1.3.4 short form length octets */
return b1;
}
if (b1 == 0x80) {
/* Indefinite length is not allowed in DER. */
return -1;
}
/* X.690-207 8.1.3.5 long form length octets */
lenleft = b1 & 0x7F;
if (lenleft > sigend - *sigp) {
return -1;
}
if (**sigp == 0) {
/* Not the shortest possible length encoding. */
return -1;
}
if ((size_t)lenleft > sizeof(size_t)) {
/* The resulting length would exceed the range of a size_t, so
* certainly longer than the passed array size.
*/
return -1;
}
while (lenleft > 0) {
if ((ret >> ((sizeof(size_t) - 1) * 8)) != 0) {
}
ret = (ret << 8) | **sigp;
if (ret + lenleft > (size_t)(sigend - *sigp)) {
/* Result exceeds the length of the passed array. */
return -1;
}
(*sigp)++;
lenleft--;
}
if (ret < 128) {
/* Not the shortest possible length encoding. */
return -1;
}
return ret;
}
static int secp256k1_der_parse_integer(secp256k1_scalar *r, const unsigned char **sig, const unsigned char *sigend) {
int overflow = 0;
unsigned char ra[32] = {0};
int rlen;
if (*sig == sigend || **sig != 0x02) {
/* Not a primitive integer (X.690-0207 8.3.1). */
return 0;
}
(*sig)++;
rlen = secp256k1_der_read_len(sig, sigend);
if (rlen <= 0 || (*sig) + rlen > sigend) {
/* Exceeds bounds or not at least length 1 (X.690-0207 8.3.1). */
return 0;
}
if (**sig == 0x00 && rlen > 1 && (((*sig)[1]) & 0x80) == 0x00) {
/* Excessive 0x00 padding. */
return 0;
}
if (**sig == 0xFF && rlen > 1 && (((*sig)[1]) & 0x80) == 0x80) {
/* Excessive 0xFF padding. */
return 0;
}
if ((**sig & 0x80) == 0x80) {
/* Negative. */
overflow = 1;
}
while (rlen > 0 && **sig == 0) {
/* Skip leading zero bytes */
rlen--;
(*sig)++;
}
if (rlen > 32) {
overflow = 1;
}
if (!overflow) {
memcpy(ra + 32 - rlen, *sig, rlen);
secp256k1_scalar_set_b32(r, ra, &overflow);
}
if (overflow) {
secp256k1_scalar_set_int(r, 0);
}
(*sig) += rlen;
return 1;
}
static int secp256k1_ecdsa_sig_parse(secp256k1_scalar *rr, secp256k1_scalar *rs, const unsigned char *sig, size_t size) {
unsigned char ra[32] = {0}, sa[32] = {0};
const unsigned char *rp;
const unsigned char *sp;
size_t lenr;
size_t lens;
int overflow;
if (sig[0] != 0x30) {
const unsigned char *sigend = sig + size;
int rlen;
if (sig == sigend || *(sig++) != 0x30) {
/* The encoding doesn't start with a constructed sequence (X.690-0207 8.9.1). */
return 0;
}
lenr = sig[3];
if (5+lenr >= size) {
rlen = secp256k1_der_read_len(&sig, sigend);
if (rlen < 0 || sig + rlen > sigend) {
/* Tuple exceeds bounds */
return 0;
}
lens = sig[lenr+5];
if (sig[1] != lenr+lens+4) {
if (sig + rlen != sigend) {
/* Garbage after tuple. */
return 0;
}
if (lenr+lens+6 > size) {
if (!secp256k1_der_parse_integer(rr, &sig, sigend)) {
return 0;
}
if (sig[2] != 0x02) {
if (!secp256k1_der_parse_integer(rs, &sig, sigend)) {
return 0;
}
if (lenr == 0) {
return 0;
}
if (sig[lenr+4] != 0x02) {
return 0;
}
if (lens == 0) {
return 0;
}
sp = sig + 6 + lenr;
while (lens > 0 && sp[0] == 0) {
lens--;
sp++;
}
if (lens > 32) {
return 0;
}
rp = sig + 4;
while (lenr > 0 && rp[0] == 0) {
lenr--;
rp++;
}
if (lenr > 32) {
return 0;
}
memcpy(ra + 32 - lenr, rp, lenr);
memcpy(sa + 32 - lens, sp, lens);
overflow = 0;
secp256k1_scalar_set_b32(rr, ra, &overflow);
if (overflow) {
return 0;
}
secp256k1_scalar_set_b32(rs, sa, &overflow);
if (overflow) {
if (sig != sigend) {
/* Trailing garbage inside tuple. */
return 0;
}
return 1;
}
@@ -136,7 +203,9 @@ static int secp256k1_ecdsa_sig_serialize(unsigned char *sig, size_t *size, const
static int secp256k1_ecdsa_sig_verify(const secp256k1_ecmult_context *ctx, const secp256k1_scalar *sigr, const secp256k1_scalar *sigs, const secp256k1_ge *pubkey, const secp256k1_scalar *message) {
unsigned char c[32];
secp256k1_scalar sn, u1, u2;
#if !defined(EXHAUSTIVE_TEST_ORDER)
secp256k1_fe xr;
#endif
secp256k1_gej pubkeyj;
secp256k1_gej pr;
@@ -152,6 +221,19 @@ static int secp256k1_ecdsa_sig_verify(const secp256k1_ecmult_context *ctx, const
if (secp256k1_gej_is_infinity(&pr)) {
return 0;
}
#if defined(EXHAUSTIVE_TEST_ORDER)
{
secp256k1_scalar computed_r;
secp256k1_ge pr_ge;
secp256k1_ge_set_gej(&pr_ge, &pr);
secp256k1_fe_normalize(&pr_ge.x);
secp256k1_fe_get_b32(c, &pr_ge.x);
secp256k1_scalar_set_b32(&computed_r, c, NULL);
return secp256k1_scalar_eq(sigr, &computed_r);
}
#else
secp256k1_scalar_get_b32(c, sigr);
secp256k1_fe_set_b32(&xr, c);
@@ -172,11 +254,11 @@ static int secp256k1_ecdsa_sig_verify(const secp256k1_ecmult_context *ctx, const
* secp256k1_gej_eq_x implements the (xr * pr.z^2 mod p == pr.x) test.
*/
if (secp256k1_gej_eq_x_var(&xr, &pr)) {
/* xr.x == xr * xr.z^2 mod p, so the signature is valid. */
/* xr * pr.z^2 mod p == pr.x, so the signature is valid. */
return 1;
}
if (secp256k1_fe_cmp_var(&xr, &secp256k1_ecdsa_const_p_minus_order) >= 0) {
/* xr + p >= n, so we can skip testing the second case. */
/* xr + n >= p, so we can skip testing the second case. */
return 0;
}
secp256k1_fe_add(&xr, &secp256k1_ecdsa_const_order_as_fe);
@@ -185,39 +267,7 @@ static int secp256k1_ecdsa_sig_verify(const secp256k1_ecmult_context *ctx, const
return 1;
}
return 0;
}
static int secp256k1_ecdsa_sig_recover(const secp256k1_ecmult_context *ctx, const secp256k1_scalar *sigr, const secp256k1_scalar* sigs, secp256k1_ge *pubkey, const secp256k1_scalar *message, int recid) {
unsigned char brx[32];
secp256k1_fe fx;
secp256k1_ge x;
secp256k1_gej xj;
secp256k1_scalar rn, u1, u2;
secp256k1_gej qj;
if (secp256k1_scalar_is_zero(sigr) || secp256k1_scalar_is_zero(sigs)) {
return 0;
}
secp256k1_scalar_get_b32(brx, sigr);
VERIFY_CHECK(secp256k1_fe_set_b32(&fx, brx)); /* brx comes from a scalar, so is less than the order; certainly less than p */
if (recid & 2) {
if (secp256k1_fe_cmp_var(&fx, &secp256k1_ecdsa_const_p_minus_order) >= 0) {
return 0;
}
secp256k1_fe_add(&fx, &secp256k1_ecdsa_const_order_as_fe);
}
if (!secp256k1_ge_set_xo_var(&x, &fx, recid & 1)) {
return 0;
}
secp256k1_gej_set_ge(&xj, &x);
secp256k1_scalar_inverse_var(&rn, sigr);
secp256k1_scalar_mul(&u1, &rn, message);
secp256k1_scalar_negate(&u1, &u1);
secp256k1_scalar_mul(&u2, &rn, sigs);
secp256k1_ecmult(ctx, &qj, &xj, &u2, &u1);
secp256k1_ge_set_gej_var(pubkey, &qj);
return !secp256k1_gej_is_infinity(&qj);
#endif
}
static int secp256k1_ecdsa_sig_sign(const secp256k1_ecmult_gen_context *ctx, secp256k1_scalar *sigr, secp256k1_scalar *sigs, const secp256k1_scalar *seckey, const secp256k1_scalar *message, const secp256k1_scalar *nonce, int *recid) {
@@ -233,13 +283,14 @@ static int secp256k1_ecdsa_sig_sign(const secp256k1_ecmult_gen_context *ctx, sec
secp256k1_fe_normalize(&r.y);
secp256k1_fe_get_b32(b, &r.x);
secp256k1_scalar_set_b32(sigr, b, &overflow);
if (secp256k1_scalar_is_zero(sigr)) {
/* P.x = order is on the curve, so technically sig->r could end up zero, which would be an invalid signature. */
secp256k1_gej_clear(&rp);
secp256k1_ge_clear(&r);
return 0;
}
/* These two conditions should be checked before calling */
VERIFY_CHECK(!secp256k1_scalar_is_zero(sigr));
VERIFY_CHECK(overflow == 0);
if (recid) {
/* The overflow condition is cryptographically unreachable as hitting it requires finding the discrete log
* of some P where P.x >= order, and only 1 in about 2^127 points meet this criteria.
*/
*recid = (overflow ? 2 : 0) | (secp256k1_fe_is_odd(&r.y) ? 1 : 0);
}
secp256k1_scalar_mul(&n, sigr, seckey);