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Revert "add more precomputation to ecdsa signing"
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This reverts commit 06dd166.
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@prusnak
prusnak committed Jul 2, 2014
1 parent 3308cc6 commit 3747ba4
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Showing 4 changed files with 74 additions and 611 deletions.
130 changes: 54 additions & 76 deletions bignum.c
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Original file line number Diff line number Diff line change
Expand Up @@ -303,20 +303,14 @@ void bn_inverse(bignum256 *x, const bignum256 *prime)
void bn_inverse(bignum256 *x, const bignum256 *prime)
{
int i, j, k, len1, len2, mask;
uint8_t buf[32];
uint32_t u[8], v[8], s[9], r[10], temp32;
uint64_t temp, temp2;
uint32_t u[9], v[9], s[10], r[10], temp, temp2;
bn_fast_mod(x, prime);
bn_mod(x, prime);
bn_write_be(prime, buf);
for (i = 0; i < 8; i++) {
u[i] = read_be(buf + 28 - i * 4);
}
bn_write_be(x, buf);
for (i = 0; i < 8; i++) {
v[i] = read_be(buf + 28 - i * 4);
for (i = 0; i < 9; i++) {
u[i] = prime->val[i];
v[i] = x->val[i];
}
len1 = 8;
len1 = 9;
s[0] = 1;
r[0] = 0;
len2 = 1;
Expand All @@ -333,13 +327,13 @@ void bn_inverse(bignum256 *x, const bignum256 *prime)
if (i == 0) break;
mask = (1 << i) - 1;
for (j = 0; j + 1 < len1; j++) {
u[j] = (u[j] >> i) | ((u[j + 1] & mask) << (32 - i));
u[j] = (u[j] >> i) | ((u[j + 1] & mask) << (30 - i));
}
u[j] = (u[j] >> i);
mask = (1 << (32 - i)) - 1;
s[len2] = s[len2 - 1] >> (32 - i);
mask = (1 << (30 - i)) - 1;
s[len2] = s[len2 - 1] >> (30 - i);
for (j = len2 - 1; j > 0; j--) {
s[j] = (s[j - 1] >> (32 - i)) | ((s[j] & mask) << i);
s[j] = (s[j - 1] >> (30 - i)) | ((s[j] & mask) << i);
}
s[0] = (s[0] & mask) << i;
if (s[len2]) {
Expand All @@ -355,13 +349,13 @@ void bn_inverse(bignum256 *x, const bignum256 *prime)
if (i == 0) break;
mask = (1 << i) - 1;
for (j = 0; j + 1 < len1; j++) {
v[j] = (v[j] >> i) | ((v[j + 1] & mask) << (32 - i));
v[j] = (v[j] >> i) | ((v[j + 1] & mask) << (30 - i));
}
v[j] = (v[j] >> i);
mask = (1 << (32 - i)) - 1;
r[len2] = r[len2 - 1] >> (32 - i);
mask = (1 << (30 - i)) - 1;
r[len2] = r[len2 - 1] >> (30 - i);
for (j = len2 - 1; j > 0; j--) {
r[j] = (r[j - 1] >> (32 - i)) | ((r[j] & mask) << i);
r[j] = (r[j - 1] >> (30 - i)) | ((r[j] & mask) << i);
}
r[0] = (r[0] & mask) << i;
if (r[len2]) {
Expand All @@ -374,51 +368,47 @@ void bn_inverse(bignum256 *x, const bignum256 *prime)
i = len1 - 1;
while (i > 0 && u[i] == v[i]) i--;
if (u[i] > v[i]) {
temp = 0x100000000ull + u[0] - v[0];
u[0] = (temp >> 1) & 0x7FFFFFFF;
temp >>= 32;
temp = 0x40000000u + u[0] - v[0];
u[0] = (temp >> 1) & 0x1FFFFFFF;
temp >>= 30;
for (i = 1; i < len1; i++) {
temp += 0xFFFFFFFFull + u[i] - v[i];
u[i - 1] += (temp & 1) << 31;
u[i] = (temp >> 1) & 0x7FFFFFFF;
temp >>= 32;
temp += 0x3FFFFFFFu + u[i] - v[i];
u[i - 1] += (temp & 1) << 29;
u[i] = (temp >> 1) & 0x1FFFFFFF;
temp >>= 30;
}
temp = temp2 = 0;
for (i = 0; i < len2; i++) {
temp += s[i];
temp += r[i];
temp2 += s[i];
temp2 += s[i];
r[i] = temp;
s[i] = temp2;
temp >>= 32;
temp2 >>= 32;
temp += s[i] + r[i];
temp2 += s[i] << 1;
r[i] = temp & 0x3FFFFFFF;
s[i] = temp2 & 0x3FFFFFFF;
temp >>= 30;
temp2 >>= 30;
}
if (temp != 0 || temp2 != 0) {
r[len2] = temp;
s[len2] = temp2;
len2++;
}
} else {
temp = 0x100000000ull + v[0] - u[0];
v[0] = (temp >> 1) & 0x7FFFFFFF;
temp >>= 32;
temp = 0x40000000u + v[0] - u[0];
v[0] = (temp >> 1) & 0x1FFFFFFF;
temp >>= 30;
for (i = 1; i < len1; i++) {
temp += 0xFFFFFFFFull + v[i] - u[i];
v[i - 1] += (temp & 1) << 31;
v[i] = (temp >> 1) & 0x7FFFFFFF;
temp >>= 32;
temp += 0x3FFFFFFFu + v[i] - u[i];
v[i - 1] += (temp & 1) << 29;
v[i] = (temp >> 1) & 0x1FFFFFFF;
temp >>= 30;
}
temp = temp2 = 0;
for (i = 0; i < len2; i++) {
temp += s[i];
temp += r[i];
temp2 += r[i];
temp2 += r[i];
s[i] = temp;
r[i] = temp2;
temp >>= 32;
temp2 >>= 32;
temp += s[i] + r[i];
temp2 += r[i] << 1;
s[i] = temp & 0x3FFFFFFF;
r[i] = temp2 & 0x3FFFFFFF;
temp >>= 30;
temp2 >>= 30;
}
if (temp != 0 || temp2 != 0) {
s[len2] = temp;
Expand All @@ -429,33 +419,21 @@ void bn_inverse(bignum256 *x, const bignum256 *prime)
if (u[len1 - 1] == 0 && v[len1 - 1] == 0) len1--;
k++;
}

j = r[0] >> 30;
r[0] = r[0] & 0x3FFFFFFFu;
for (i = 1; i < len2; i++) {
uint32_t q = r[i] >> (30 - 2 * i);
r[i] = ((r[i] << (2 * i)) & 0x3FFFFFFFu) + j;
j=q;
}
r[i] = j;
i++;
for (; i < 9; i++) r[i] = 0;

i = 8;
while (i > 0 && r[i] == prime->val[i]) i--;
if (r[i] >= prime->val[i]) {
temp32 = 1;
temp = 1;
for (i = 0; i < 9; i++) {
temp32 += 0x3FFFFFFF + r[i] - prime->val[i];
r[i] = temp32 & 0x3FFFFFFF;
temp32 >>= 30;
temp += 0x3FFFFFFF + r[i] - prime->val[i];
r[i] = temp & 0x3FFFFFFF;
temp >>= 30;
}
}
temp32 = 1;
temp = 1;
for (i = 0; i < 9; i++) {
temp32 += 0x3FFFFFFF + prime->val[i] - r[i];
r[i] = temp32 & 0x3FFFFFFF;
temp32 >>= 30;
temp += 0x3FFFFFFF + prime->val[i] - r[i];
r[i] = temp & 0x3FFFFFFF;
temp >>= 30;
}
int done = 0;
#if USE_PRECOMPUTED_IV
Expand All @@ -471,14 +449,14 @@ void bn_inverse(bignum256 *x, const bignum256 *prime)
if (!done) {
for (j = 0; j < k; j++) {
if (r[0] & 1) {
temp32 = r[0] + prime->val[0];
r[0] = (temp32 >> 1) & 0x1FFFFFFF;
temp32 >>= 30;
temp = r[0] + prime->val[0];
r[0] = (temp >> 1) & 0x1FFFFFFF;
temp >>= 30;
for (i = 1; i < 9; i++) {
temp32 += r[i] + prime->val[i];
r[i - 1] += (temp32 & 1) << 29;
r[i] = (temp32 >> 1) & 0x1FFFFFFF;
temp32 >>= 30;
temp += r[i] + prime->val[i];
r[i - 1] += (temp & 1) << 29;
r[i] = (temp >> 1) & 0x1FFFFFFF;
temp >>= 30;
}
} else {
for (i = 0; i < 8; i++) {
Expand Down
41 changes: 20 additions & 21 deletions ecdsa.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -123,39 +123,38 @@ void point_multiply(const bignum256 *k, const curve_point *p, curve_point *res)
// res = k * G
void scalar_multiply(const bignum256 *k, curve_point *res)
{
int i;
int i, j;
// result is zero
int is_zero = 1;
#if USE_PRECOMPUTED_CP
int exp = 0;
#else
curve_point curr;
// initial res
memcpy(&curr, &G256k1, sizeof(curve_point));
for (i = 0; i < 256; i++) {
if (k->val[i / 30] & (1u << (i % 30))) {
if (is_zero) {
#endif
for (i = 0; i < 9; i++) {
for (j = 0; j < 30; j++) {
if (i == 8 && (k->val[i] >> j) == 0) break;
if (k->val[i] & (1u << j)) {
if (is_zero) {
#if USE_PRECOMPUTED_CP
if (i < 255 && (k->val[(i + 1) / 30] & (1u << ((i + 1) % 30)))) {
memcpy(res, secp256k1_cp2 + i, sizeof(curve_point));
i++;
} else {
memcpy(res, secp256k1_cp + i, sizeof(curve_point));
}
memcpy(res, secp256k1_cp + exp, sizeof(curve_point));
#else
memcpy(res, &curr, sizeof(curve_point));
memcpy(res, &curr, sizeof(curve_point));
#endif
is_zero = 0;
} else {
#if USE_PRECOMPUTED_CP
if (i < 255 && (k->val[(i + 1) / 30] & (1u << ((i + 1) % 30)))) {
point_add(secp256k1_cp2 + i, res);
i++;
is_zero = 0;
} else {
point_add(secp256k1_cp + i, res);
}
#if USE_PRECOMPUTED_CP
point_add(secp256k1_cp + exp, res);
#else
point_add(&curr, res);
point_add(&curr, res);
#endif
}
}
#if ! USE_PRECOMPUTED_CP
#if USE_PRECOMPUTED_CP
exp++;
#else
point_double(&curr);
#endif
}
Expand Down

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