aboutsummaryrefslogtreecommitdiff
path: root/src/ringct/rctSigs.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/ringct/rctSigs.cpp')
-rw-r--r--src/ringct/rctSigs.cpp75
1 files changed, 40 insertions, 35 deletions
diff --git a/src/ringct/rctSigs.cpp b/src/ringct/rctSigs.cpp
index ff2a81d43..a7b265d63 100644
--- a/src/ringct/rctSigs.cpp
+++ b/src/ringct/rctSigs.cpp
@@ -163,14 +163,11 @@ namespace rct {
return verifyBorromean(bb, P1_p3, P2_p3);
}
- //Multilayered Spontaneous Anonymous Group Signatures (MLSAG signatures)
- //This is a just slghtly more efficient version than the ones described below
- //(will be explained in more detail in Ring Multisig paper
- //These are aka MG signatutes in earlier drafts of the ring ct paper
- // c.f. https://eprint.iacr.org/2015/1098 section 2.
- // Gen creates a signature which proves that for some column in the keymatrix "pk"
- // the signer knows a secret key for each row in that column
- // Ver verifies that the MG sig was created correctly
+ // MLSAG signatures
+ // See paper by Noether (https://eprint.iacr.org/2015/1098)
+ // This generalization allows for some dimensions not to require linkability;
+ // this is used in practice for commitment data within signatures
+ // Note that using more than one linkable dimension is not recommended.
mgSig MLSAG_Gen(const key &message, const keyM & pk, const keyV & xx, const multisig_kLRki *kLRki, key *mscout, const unsigned int index, size_t dsRows, hw::device &hwdev) {
mgSig rv;
size_t cols = pk.size();
@@ -188,6 +185,7 @@ namespace rct {
size_t i = 0, j = 0, ii = 0;
key c, c_old, L, R, Hi;
+ ge_p3 Hi_p3;
sc_0(c_old.bytes);
vector<geDsmp> Ip(dsRows);
rv.II = keyV(dsRows);
@@ -208,7 +206,8 @@ namespace rct {
rv.II[i] = kLRki->ki;
}
else {
- Hi = hashToPoint(pk[index][i]);
+ hash_to_p3(Hi_p3, pk[index][i]);
+ ge_p3_tobytes(Hi.bytes, &Hi_p3);
hwdev.mlsag_prepare(Hi, xx[i], alpha[i] , aG[i] , aHP[i] , rv.II[i]);
toHash[3 * i + 2] = aG[i];
toHash[3 * i + 3] = aHP[i];
@@ -235,7 +234,8 @@ namespace rct {
sc_0(c.bytes);
for (j = 0; j < dsRows; j++) {
addKeys2(L, rv.ss[i][j], c_old, pk[i][j]);
- hashToPoint(Hi, pk[i][j]);
+ hash_to_p3(Hi_p3, pk[i][j]);
+ ge_p3_tobytes(Hi.bytes, &Hi_p3);
addKeys3(R, rv.ss[i][j], Hi, c_old, Ip[j].k);
toHash[3 * j + 1] = pk[i][j];
toHash[3 * j + 2] = L;
@@ -260,43 +260,42 @@ namespace rct {
return rv;
}
- //Multilayered Spontaneous Anonymous Group Signatures (MLSAG signatures)
- //This is a just slghtly more efficient version than the ones described below
- //(will be explained in more detail in Ring Multisig paper
- //These are aka MG signatutes in earlier drafts of the ring ct paper
- // c.f. https://eprint.iacr.org/2015/1098 section 2.
- // Gen creates a signature which proves that for some column in the keymatrix "pk"
- // the signer knows a secret key for each row in that column
- // Ver verifies that the MG sig was created correctly
+ // MLSAG signatures
+ // See paper by Noether (https://eprint.iacr.org/2015/1098)
+ // This generalization allows for some dimensions not to require linkability;
+ // this is used in practice for commitment data within signatures
+ // Note that using more than one linkable dimension is not recommended.
bool MLSAG_Ver(const key &message, const keyM & pk, const mgSig & rv, size_t dsRows) {
-
size_t cols = pk.size();
- CHECK_AND_ASSERT_MES(cols >= 2, false, "Error! What is c if cols = 1!");
+ CHECK_AND_ASSERT_MES(cols >= 2, false, "Signature must contain more than one public key");
size_t rows = pk[0].size();
- CHECK_AND_ASSERT_MES(rows >= 1, false, "Empty pk");
+ CHECK_AND_ASSERT_MES(rows >= 1, false, "Bad total row number");
for (size_t i = 1; i < cols; ++i) {
- CHECK_AND_ASSERT_MES(pk[i].size() == rows, false, "pk is not rectangular");
+ CHECK_AND_ASSERT_MES(pk[i].size() == rows, false, "Bad public key matrix dimensions");
}
- CHECK_AND_ASSERT_MES(rv.II.size() == dsRows, false, "Bad II size");
- CHECK_AND_ASSERT_MES(rv.ss.size() == cols, false, "Bad rv.ss size");
+ CHECK_AND_ASSERT_MES(rv.II.size() == dsRows, false, "Wrong number of key images present");
+ CHECK_AND_ASSERT_MES(rv.ss.size() == cols, false, "Bad scalar matrix dimensions");
for (size_t i = 0; i < cols; ++i) {
- CHECK_AND_ASSERT_MES(rv.ss[i].size() == rows, false, "rv.ss is not rectangular");
+ CHECK_AND_ASSERT_MES(rv.ss[i].size() == rows, false, "Bad scalar matrix dimensions");
}
- CHECK_AND_ASSERT_MES(dsRows <= rows, false, "Bad dsRows value");
+ CHECK_AND_ASSERT_MES(dsRows <= rows, false, "Non-double-spend rows cannot exceed total rows");
- for (size_t i = 0; i < rv.ss.size(); ++i)
- for (size_t j = 0; j < rv.ss[i].size(); ++j)
- CHECK_AND_ASSERT_MES(sc_check(rv.ss[i][j].bytes) == 0, false, "Bad ss slot");
- CHECK_AND_ASSERT_MES(sc_check(rv.cc.bytes) == 0, false, "Bad cc");
+ for (size_t i = 0; i < rv.ss.size(); ++i) {
+ for (size_t j = 0; j < rv.ss[i].size(); ++j) {
+ CHECK_AND_ASSERT_MES(sc_check(rv.ss[i][j].bytes) == 0, false, "Bad signature scalar");
+ }
+ }
+ CHECK_AND_ASSERT_MES(sc_check(rv.cc.bytes) == 0, false, "Bad initial signature hash");
size_t i = 0, j = 0, ii = 0;
- key c, L, R, Hi;
+ key c, L, R;
key c_old = copy(rv.cc);
vector<geDsmp> Ip(dsRows);
for (i = 0 ; i < dsRows ; i++) {
+ CHECK_AND_ASSERT_MES(!(rv.II[i] == rct::identity()), false, "Bad key image");
precomp(Ip[i].k, rv.II[i]);
}
- size_t ndsRows = 3 * dsRows; //non Double Spendable Rows (see identity chains paper
+ size_t ndsRows = 3 * dsRows; // number of dimensions not requiring linkability
keyV toHash(1 + 3 * dsRows + 2 * (rows - dsRows));
toHash[0] = message;
i = 0;
@@ -304,9 +303,14 @@ namespace rct {
sc_0(c.bytes);
for (j = 0; j < dsRows; j++) {
addKeys2(L, rv.ss[i][j], c_old, pk[i][j]);
- hashToPoint(Hi, pk[i][j]);
- CHECK_AND_ASSERT_MES(!(Hi == rct::identity()), false, "Data hashed to point at infinity");
- addKeys3(R, rv.ss[i][j], Hi, c_old, Ip[j].k);
+
+ // Compute R directly
+ ge_p3 hash8_p3;
+ hash_to_p3(hash8_p3, pk[i][j]);
+ ge_p2 R_p2;
+ ge_double_scalarmult_precomp_vartime(&R_p2, rv.ss[i][j].bytes, &hash8_p3, c_old.bytes, Ip[j].k);
+ ge_tobytes(R.bytes, &R_p2);
+
toHash[3 * j + 1] = pk[i][j];
toHash[3 * j + 2] = L;
toHash[3 * j + 3] = R;
@@ -317,6 +321,7 @@ namespace rct {
toHash[ndsRows + 2 * ii + 2] = L;
}
c = hash_to_scalar(toHash);
+ CHECK_AND_ASSERT_MES(!(c == rct::zero()), false, "Bad signature hash");
copy(c_old, c);
i = (i + 1);
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-15 01:31:15 +0000