Integrate CLSAGs into monero

They are allowed from v12, and MLSAGs are rejected from v13.

1 files changed, 166 insertions, 18 deletions

diff --git a/src/ringct/rctSigs.cpp b/src/ringct/rctSigs.cpp
index cb702ed15..074812156 100644
--- a/src/ringct/rctSigs.cpp
+++ b/src/ringct/rctSigs.cpp
@@ -168,11 +168,14 @@ namespace rct {
 
     // Generate a CLSAG signature
     // See paper by Goodell et al. (https://eprint.iacr.org/2019/654)
-    clsag CLSAG_Gen(const key &message, const keyV & P, const key & p, const keyV & C, const key & z, const unsigned int l, const multisig_kLRki *kLRki) {
+    clsag CLSAG_Gen(const key &message, const keyV & P, const key & p, const keyV & C, const key & z, const unsigned int l, const multisig_kLRki *kLRki, key *mscout, key *mspout) {
         clsag sig;
         size_t n = P.size(); // ring size
         CHECK_AND_ASSERT_THROW_MES(n == C.size(), "Signing and commitment key vector sizes must match!");
         CHECK_AND_ASSERT_THROW_MES(l < n, "Signing index out of range!");
+        CHECK_AND_ASSERT_THROW_MES(scalarmultBase(z) == C[l], "C does not match z!");
+        CHECK_AND_ASSERT_THROW_MES((kLRki && mscout) || (!kLRki && !mscout), "Only one of kLRki/mscout is present");
+        CHECK_AND_ASSERT_THROW_MES((mscout && mspout) || !kLRki, "Multisig pointers are not all present");
 
         // Key images
         ge_p3 H_p3;
@@ -309,9 +312,18 @@ namespace rct {
         sc_muladd(s0_add_z_mu_C.bytes,mu_C.bytes,z.bytes,s0_p_mu_P.bytes);
         sc_mulsub(sig.s[l].bytes,c.bytes,s0_add_z_mu_C.bytes,a.bytes);
 
+        if (mscout)
+          *mscout = c;
+        if (mspout)
+          *mspout = mu_P;
+
         return sig;
     }
 
+    clsag CLSAG_Gen(const key &message, const keyV & P, const key & p, const keyV & C, const key & z, const unsigned int l) {
+        return CLSAG_Gen(message, P, p, C, z, l, NULL, NULL, NULL);
+    }
+
     // Verify a CLSAG signature
     // See paper by Goodell et al. (https://eprint.iacr.org/2019/654)
     bool CLSAG_Ver(const key &message, const keyV & P, const keyV & C, const clsag & sig)
@@ -665,7 +677,7 @@ namespace rct {
       hashes.push_back(hash2rct(h));
 
       keyV kv;
-      if (rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2)
+      if (rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG)
       {
         kv.reserve((6*2+9) * rv.p.bulletproofs.size());
         for (const auto &p: rv.p.bulletproofs)
@@ -793,6 +805,35 @@ namespace rct {
         return result;
     }
 
+    clsag proveRctCLSAGSimple(const key &message, const ctkeyV &pubs, const ctkey &inSk, const key &a, const key &Cout, const multisig_kLRki *kLRki, key *mscout, key *mspout, unsigned int index, hw::device &hwdev) {
+        //setup vars
+        size_t rows = 1;
+        size_t cols = pubs.size();
+        CHECK_AND_ASSERT_THROW_MES(cols >= 1, "Empty pubs");
+        CHECK_AND_ASSERT_THROW_MES((kLRki && mscout) || (!kLRki && !mscout), "Only one of kLRki/mscout is present");
+        keyV tmp(rows + 1);
+        keyV sk(rows + 1);
+        size_t i;
+        keyM M(cols, tmp);
+
+        keyV P, C;
+        P.reserve(pubs.size());
+        C.reserve(pubs.size());
+        for (const ctkey &k: pubs)
+        {
+            P.push_back(k.dest);
+            rct::key tmp;
+            subKeys(tmp, k.mask, Cout);
+            C.push_back(tmp);
+        }
+
+        sk[0] = copy(inSk.dest);
+        sc_sub(sk[1].bytes, inSk.mask.bytes, a.bytes);
+        clsag result = CLSAG_Gen(message, P, sk[0], C, sk[1], index, kLRki, mscout, mspout);
+        memwipe(sk.data(), sk.size() * sizeof(key));
+        return result;
+    }
+
 
     //Ring-ct MG sigs
     //Prove: 
@@ -872,6 +913,33 @@ namespace rct {
         catch (...) { return false; }
     }
 
+    bool verRctCLSAGSimple(const key &message, const clsag &clsag, const ctkeyV & pubs, const key & C) {
+        try
+        {
+            PERF_TIMER(verRctCLSAGSimple);
+            //setup vars
+            const size_t cols = pubs.size();
+            CHECK_AND_ASSERT_MES(cols >= 1, false, "Empty pubs");
+            keyV Pi(cols), Ci(cols);
+            ge_p3 Cp3;
+            CHECK_AND_ASSERT_MES_L1(ge_frombytes_vartime(&Cp3, C.bytes) == 0, false, "point conv failed");
+            ge_cached Ccached;
+            ge_p3_to_cached(&Ccached, &Cp3);
+            ge_p1p1 p1;
+            //create the matrix to mg sig
+            for (size_t i = 0; i < cols; i++) {
+                    Pi[i] = pubs[i].dest;
+                    ge_p3 p3;
+                    CHECK_AND_ASSERT_MES_L1(ge_frombytes_vartime(&p3, pubs[i].mask.bytes) == 0, false, "point conv failed");
+                    ge_sub(&p1, &p3, &Ccached);
+                    ge_p1p1_to_p3(&p3, &p1);
+                    ge_p3_tobytes(Ci[i].bytes, &p3);
+            }
+            return CLSAG_Ver(message, Pi, Ci, clsag);
+        }
+        catch (...) { return false; }
+    }
+
 
     //These functions get keys from blockchain
     //replace these when connecting blockchain
@@ -964,7 +1032,7 @@ namespace rct {
             //mask amount and mask
             rv.ecdhInfo[i].mask = copy(outSk[i].mask);
             rv.ecdhInfo[i].amount = d2h(amounts[i]);
-            hwdev.ecdhEncode(rv.ecdhInfo[i], amount_keys[i], rv.type == RCTTypeBulletproof2);
+            hwdev.ecdhEncode(rv.ecdhInfo[i], amount_keys[i], rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG);
         }
 
         //set txn fee
@@ -1012,7 +1080,27 @@ namespace rct {
         }
 
         rctSig rv;
-        rv.type = bulletproof ? (rct_config.bp_version == 0 || rct_config.bp_version >= 2 ? RCTTypeBulletproof2 : RCTTypeBulletproof) : RCTTypeSimple;
+        if (bulletproof)
+        {
+          switch (rct_config.bp_version)
+          {
+            case 0:
+            case 3:
+              rv.type = RCTTypeCLSAG;
+              break;
+            case 2:
+              rv.type = RCTTypeBulletproof2;
+              break;
+            case 1:
+              rv.type = RCTTypeBulletproof;
+              break;
+            default:
+              ASSERT_MES_AND_THROW("Unsupported BP version: " << rct_config.bp_version);
+          }
+        }
+        else
+          rv.type = RCTTypeSimple;
+
         rv.message = message;
         rv.outPk.resize(destinations.size());
         if (!bulletproof)
@@ -1102,7 +1190,7 @@ namespace rct {
             //mask amount and mask
             rv.ecdhInfo[i].mask = copy(outSk[i].mask);
             rv.ecdhInfo[i].amount = d2h(outamounts[i]);
-            hwdev.ecdhEncode(rv.ecdhInfo[i], amount_keys[i], rv.type == RCTTypeBulletproof2);
+            hwdev.ecdhEncode(rv.ecdhInfo[i], amount_keys[i], rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG);
         }
             
         //set txn fee
@@ -1112,7 +1200,10 @@ namespace rct {
         rv.mixRing = mixRing;
         keyV &pseudoOuts = bulletproof ? rv.p.pseudoOuts : rv.pseudoOuts;
         pseudoOuts.resize(inamounts.size());
-        rv.p.MGs.resize(inamounts.size());
+        if (rv.type == RCTTypeCLSAG)
+            rv.p.CLSAGs.resize(inamounts.size());
+        else
+            rv.p.MGs.resize(inamounts.size());
         key sumpouts = zero(); //sum pseudoOut masks
         keyV a(inamounts.size());
         for (i = 0 ; i < inamounts.size() - 1; i++) {
@@ -1126,9 +1217,20 @@ namespace rct {
 
         key full_message = get_pre_mlsag_hash(rv,hwdev);
         if (msout)
-          msout->c.resize(inamounts.size());
-        for (i = 0 ; i < inamounts.size(); i++) {
-            rv.p.MGs[i] = proveRctMGSimple(full_message, rv.mixRing[i], inSk[i], a[i], pseudoOuts[i], kLRki ? &(*kLRki)[i]: NULL, msout ? &msout->c[i] : NULL, index[i], hwdev);
+        {
+            msout->c.resize(inamounts.size());
+            msout->mu_p.resize(rv.type == RCTTypeCLSAG ? inamounts.size() : 0);
+        }
+        for (i = 0 ; i < inamounts.size(); i++)
+        {
+            if (rv.type == RCTTypeCLSAG)
+            {
+                rv.p.CLSAGs[i] = proveRctCLSAGSimple(full_message, rv.mixRing[i], inSk[i], a[i], pseudoOuts[i], kLRki ? &(*kLRki)[i]: NULL, msout ? &msout->c[i] : NULL, msout ? &msout->mu_p[i] : NULL, index[i], hwdev);
+            }
+            else
+            {
+                rv.p.MGs[i] = proveRctMGSimple(full_message, rv.mixRing[i], inSk[i], a[i], pseudoOuts[i], kLRki ? &(*kLRki)[i]: NULL, msout ? &msout->c[i] : NULL, index[i], hwdev);
+            }
         }
         return rv;
     }
@@ -1233,13 +1335,22 @@ namespace rct {
         {
           CHECK_AND_ASSERT_MES(rvp, false, "rctSig pointer is NULL");
           const rctSig &rv = *rvp;
-          CHECK_AND_ASSERT_MES(rv.type == RCTTypeSimple || rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2,
+          CHECK_AND_ASSERT_MES(rv.type == RCTTypeSimple || rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG,
               false, "verRctSemanticsSimple called on non simple rctSig");
           const bool bulletproof = is_rct_bulletproof(rv.type);
           if (bulletproof)
           {
             CHECK_AND_ASSERT_MES(rv.outPk.size() == n_bulletproof_amounts(rv.p.bulletproofs), false, "Mismatched sizes of outPk and bulletproofs");
-            CHECK_AND_ASSERT_MES(rv.p.pseudoOuts.size() == rv.p.MGs.size(), false, "Mismatched sizes of rv.p.pseudoOuts and rv.p.MGs");
+            if (rv.type == RCTTypeCLSAG)
+            {
+              CHECK_AND_ASSERT_MES(rv.p.MGs.empty(), false, "MGs are not empty for CLSAG");
+              CHECK_AND_ASSERT_MES(rv.p.pseudoOuts.size() == rv.p.CLSAGs.size(), false, "Mismatched sizes of rv.p.pseudoOuts and rv.p.CLSAGs");
+            }
+            else
+            {
+              CHECK_AND_ASSERT_MES(rv.p.CLSAGs.empty(), false, "CLSAGs are not empty for MLSAG");
+              CHECK_AND_ASSERT_MES(rv.p.pseudoOuts.size() == rv.p.MGs.size(), false, "Mismatched sizes of rv.p.pseudoOuts and rv.p.MGs");
+            }
             CHECK_AND_ASSERT_MES(rv.pseudoOuts.empty(), false, "rv.pseudoOuts is not empty");
           }
           else
@@ -1333,7 +1444,7 @@ namespace rct {
       {
         PERF_TIMER(verRctNonSemanticsSimple);
 
-        CHECK_AND_ASSERT_MES(rv.type == RCTTypeSimple || rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2,
+        CHECK_AND_ASSERT_MES(rv.type == RCTTypeSimple || rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG,
             false, "verRctNonSemanticsSimple called on non simple rctSig");
         const bool bulletproof = is_rct_bulletproof(rv.type);
         // semantics check is early, and mixRing/MGs aren't resolved yet
@@ -1356,14 +1467,19 @@ namespace rct {
         results.resize(rv.mixRing.size());
         for (size_t i = 0 ; i < rv.mixRing.size() ; i++) {
           tpool.submit(&waiter, [&, i] {
-              results[i] = verRctMGSimple(message, rv.p.MGs[i], rv.mixRing[i], pseudoOuts[i]);
+              if (rv.type == RCTTypeCLSAG)
+              {
+                  results[i] = verRctCLSAGSimple(message, rv.p.CLSAGs[i], rv.mixRing[i], pseudoOuts[i]);
+              }
+              else
+                  results[i] = verRctMGSimple(message, rv.p.MGs[i], rv.mixRing[i], pseudoOuts[i]);
           });
         }
         waiter.wait(&tpool);
 
         for (size_t i = 0; i < results.size(); ++i) {
           if (!results[i]) {
-            LOG_PRINT_L1("verRctMGSimple failed for input " << i);
+            LOG_PRINT_L1("verRctMGSimple/verRctCLSAGSimple failed for input " << i);
             return false;
           }
         }
@@ -1400,7 +1516,7 @@ namespace rct {
 
         //mask amount and mask
         ecdhTuple ecdh_info = rv.ecdhInfo[i];
-        hwdev.ecdhDecode(ecdh_info, sk, rv.type == RCTTypeBulletproof2);
+        hwdev.ecdhDecode(ecdh_info, sk, rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG);
         mask = ecdh_info.mask;
         key amount = ecdh_info.amount;
         key C = rv.outPk[i].mask;
@@ -1424,13 +1540,13 @@ namespace rct {
     }
 
     xmr_amount decodeRctSimple(const rctSig & rv, const key & sk, unsigned int i, key &mask, hw::device &hwdev) {
-        CHECK_AND_ASSERT_MES(rv.type == RCTTypeSimple || rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2, false, "decodeRct called on non simple rctSig");
+        CHECK_AND_ASSERT_MES(rv.type == RCTTypeSimple || rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG, false, "decodeRct called on non simple rctSig");
         CHECK_AND_ASSERT_THROW_MES(i < rv.ecdhInfo.size(), "Bad index");
         CHECK_AND_ASSERT_THROW_MES(rv.outPk.size() == rv.ecdhInfo.size(), "Mismatched sizes of rv.outPk and rv.ecdhInfo");
 
         //mask amount and mask
         ecdhTuple ecdh_info = rv.ecdhInfo[i];
-        hwdev.ecdhDecode(ecdh_info, sk, rv.type == RCTTypeBulletproof2);
+        hwdev.ecdhDecode(ecdh_info, sk, rv.type == RCTTypeBulletproof2 || rv.type == RCTTypeCLSAG);
         mask = ecdh_info.mask;
         key amount = ecdh_info.amount;
         key C = rv.outPk[i].mask;
@@ -1453,12 +1569,13 @@ namespace rct {
       return decodeRctSimple(rv, sk, i, mask, hwdev);
     }
 
-    bool signMultisig(rctSig &rv, const std::vector<unsigned int> &indices, const keyV &k, const multisig_out &msout, const key &secret_key) {
+    bool signMultisigMLSAG(rctSig &rv, const std::vector<unsigned int> &indices, const keyV &k, const multisig_out &msout, const key &secret_key) {
         CHECK_AND_ASSERT_MES(rv.type == RCTTypeFull || rv.type == RCTTypeSimple || rv.type == RCTTypeBulletproof || rv.type == RCTTypeBulletproof2,
             false, "unsupported rct type");
         CHECK_AND_ASSERT_MES(indices.size() == k.size(), false, "Mismatched k/indices sizes");
         CHECK_AND_ASSERT_MES(k.size() == rv.p.MGs.size(), false, "Mismatched k/MGs size");
         CHECK_AND_ASSERT_MES(k.size() == msout.c.size(), false, "Mismatched k/msout.c size");
+        CHECK_AND_ASSERT_MES(rv.p.CLSAGs.empty(), false, "CLSAGs not empty for MLSAGs");
         if (rv.type == RCTTypeFull)
         {
           CHECK_AND_ASSERT_MES(rv.p.MGs.size() == 1, false, "MGs not a single element");
@@ -1468,6 +1585,8 @@ namespace rct {
             CHECK_AND_ASSERT_MES(!rv.p.MGs[n].ss[indices[n]].empty(), false, "empty ss line");
         }
 
+        // MLSAG: each player contributes a share to the secret-index ss: k - cc*secret_key_share
+        //     cc: msout.c[n], secret_key_share: secret_key
         for (size_t n = 0; n < indices.size(); ++n) {
             rct::key diff;
             sc_mulsub(diff.bytes, msout.c[n].bytes, secret_key.bytes, k[n].bytes);
@@ -1475,4 +1594,33 @@ namespace rct {
         }
         return true;
     }
+
+    bool signMultisigCLSAG(rctSig &rv, const std::vector<unsigned int> &indices, const keyV &k, const multisig_out &msout, const key &secret_key) {
+        CHECK_AND_ASSERT_MES(rv.type == RCTTypeCLSAG, false, "unsupported rct type");
+        CHECK_AND_ASSERT_MES(indices.size() == k.size(), false, "Mismatched k/indices sizes");
+        CHECK_AND_ASSERT_MES(k.size() == rv.p.CLSAGs.size(), false, "Mismatched k/MGs size");
+        CHECK_AND_ASSERT_MES(k.size() == msout.c.size(), false, "Mismatched k/msout.c size");
+        CHECK_AND_ASSERT_MES(rv.p.MGs.empty(), false, "MGs not empty for CLSAGs");
+        CHECK_AND_ASSERT_MES(msout.c.size() == msout.mu_p.size(), false, "Bad mu_p size");
+        for (size_t n = 0; n < indices.size(); ++n) {
+            CHECK_AND_ASSERT_MES(indices[n] < rv.p.CLSAGs[n].s.size(), false, "Index out of range");
+        }
+
+        // CLSAG: each player contributes a share to the secret-index ss: k - cc*mu_p*secret_key_share
+        // cc: msout.c[n], mu_p, msout.mu_p[n], secret_key_share: secret_key
+        for (size_t n = 0; n < indices.size(); ++n) {
+            rct::key diff, sk;
+            sc_mul(sk.bytes, msout.mu_p[n].bytes, secret_key.bytes);
+            sc_mulsub(diff.bytes, msout.c[n].bytes, sk.bytes, k[n].bytes);
+            sc_add(rv.p.CLSAGs[n].s[indices[n]].bytes, rv.p.CLSAGs[n].s[indices[n]].bytes, diff.bytes);
+        }
+        return true;
+    }
+
+    bool signMultisig(rctSig &rv, const std::vector<unsigned int> &indices, const keyV &k, const multisig_out &msout, const key &secret_key) {
+        if (rv.type == RCTTypeCLSAG)
+            return signMultisigCLSAG(rv, indices, k, msout, secret_key);
+        else
+            return signMultisigMLSAG(rv, indices, k, msout, secret_key);
+    }
 }