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more comprehensive test for ge_p3 comparison to identity/point at infinity

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Reported by QuarksLab.
This commit is contained in:
moneromooo-monero 2018-07-26 18:03:10 +01:00
parent d0a0565f7d
commit 463434d1f7
No known key found for this signature in database
GPG Key ID: 686F07454D6CEFC3
3 changed files with 21 additions and 6 deletions
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13
src/crypto/crypto-ops.c
View File

@ -3729,3 +3729,16 @@ int sc_isnonzero(const unsigned char *s) {
s[18] | s[19] | s[20] | s[21] | s[22] | s[23] | s[24] | s[25] | s[26] |
s[27] | s[28] | s[29] | s[30] | s[31]) - 1) >> 8) + 1;
}
int ge_p3_is_point_at_infinity(const ge_p3 *p) {
// X = 0 and Y == Z
int n;
for (n = 0; n < 10; ++n)
{
if (p->X[n] | p->T[n])
return 0;
if (p->Y[n] != p->Z[n])
return 0;
}
return 1;
}

2
src/crypto/crypto-ops.h
View File

@ -159,3 +159,5 @@ void ge_sub(ge_p1p1 *r, const ge_p3 *p, const ge_cached *q);
void fe_add(fe h, const fe f, const fe g);
void fe_tobytes(unsigned char *, const fe);
void fe_invert(fe out, const fe z);
int ge_p3_is_point_at_infinity(const ge_p3 *p);

12
src/ringct/multiexp.cc
View File

@ -216,7 +216,7 @@ rct::key bos_coster_heap_conv_robust(std::vector<MultiexpData> data)
heap.reserve(points);
for (size_t n = 0; n < points; ++n)
{
if (!(data[n].scalar == rct::zero()) && memcmp(&data[n].point, &ge_p3_identity, sizeof(ge_p3)))
if (!(data[n].scalar == rct::zero()) && !ge_p3_is_point_at_infinity(&data[n].point))
heap.push_back(n);
}
points = heap.size();
@ -442,7 +442,7 @@ rct::key straus(const std::vector<MultiexpData> &data, const std::shared_ptr<str
MULTIEXP_PERF(PERF_TIMER_START_UNIT(skip, 1000000));
std::vector<uint8_t> skip(data.size());
for (size_t i = 0; i < data.size(); ++i)
skip[i] = data[i].scalar == rct::zero() || !memcmp(&data[i].point, &ge_p3_identity, sizeof(ge_p3));
skip[i] = data[i].scalar == rct::zero() || ge_p3_is_point_at_infinity(&data[i].point);
MULTIEXP_PERF(PERF_TIMER_STOP(skip));
#endif
@ -611,7 +611,7 @@ rct::key pippenger(const std::vector<MultiexpData> &data, const std::shared_ptr<
for (size_t k = groups; k-- > 0; )
{
if (memcmp(&result, &ge_p3_identity, sizeof(ge_p3)))
if (!ge_p3_is_point_at_infinity(&result))
{
ge_p2 p2;
ge_p3_to_p2(&p2, &result);
@ -638,7 +638,7 @@ rct::key pippenger(const std::vector<MultiexpData> &data, const std::shared_ptr<
if (bucket == 0)
continue;
CHECK_AND_ASSERT_THROW_MES(bucket < (1u<<c), "bucket overflow");
if (memcmp(&buckets[bucket], &ge_p3_identity, sizeof(ge_p3)))
if (!ge_p3_is_point_at_infinity(&buckets[bucket]))
{
add(buckets[bucket], local_cache->cached[i]);
}
@ -650,9 +650,9 @@ rct::key pippenger(const std::vector<MultiexpData> &data, const std::shared_ptr<
ge_p3 pail = ge_p3_identity;
for (size_t i = (1<<c)-1; i > 0; --i)
{
if (memcmp(&buckets[i], &ge_p3_identity, sizeof(ge_p3)))
if (!ge_p3_is_point_at_infinity(&buckets[i]))
add(pail, buckets[i]);
if (memcmp(&pail, &ge_p3_identity, sizeof(ge_p3)))
if (!ge_p3_is_point_at_infinity(&pail))
add(result, pail);
}
}