Merge pull request #223 from clearmatics/mpc-other-curves

Support other curves in mpc

CMakeLists.txt

@@ -290,6 +290,6 @@ endif()
 add_subdirectory(libzeth)
 add_subdirectory(prover_server)
 # For now the MPC for Groth16 only is tailored to the alt_bn128 pairing group
-if(${ZKSNARK} STREQUAL "GROTH16" AND ${CURVE} STREQUAL "ALT_BN128")
+if(${ZKSNARK} STREQUAL "GROTH16")
   add_subdirectory(mpc_tools)
 endif()

libzeth/circuits/circuit_types.hpp

@@ -10,6 +10,8 @@
 #include "libzeth/circuits/mimc/mimc_mp.hpp"
 #include "libzeth/core/include_libsnark.hpp"
 
+#include <libff/common/default_types/ec_pp.hpp>
+
 // Types that must be common across all executable, defined once here. Outside
 // of tests, these should not be set anywhere else in the code. Do not include
 // this file in code that is generic (parameterized on ppT or FieldT).

libzeth/core/include_libff.hpp

@@ -7,8 +7,8 @@
 
 // Include minimal set of libff types for curve-independent operations.
 
+#include <libff/algebra/curves/public_params.hpp>
 #include <libff/algebra/fields/bigint.hpp>
 #include <libff/algebra/fields/field_utils.hpp>
-#include <libff/common/default_types/ec_pp.hpp>
 
 #endif // __ZETH_CORE_INCLUDE_LIBFF__

libzeth/mpc/groth16/phase2.tcc

@@ -69,6 +69,30 @@ void srs_mpc_phase2_accumulator<ppT>::write(std::ostream &out) const
     }
 }
 
+template<typename ppT>
+void srs_mpc_phase2_accumulator<ppT>::write_compressed(std::ostream &out) const
+{
+    using G1 = libff::G1<ppT>;
+    check_well_formed(*this, "mpc_layer2 (write)");
+
+    // Write cs_hash and sizes first.
+
+    const size_t H_size = H_g1.size();
+    const size_t L_size = L_g1.size();
+    out.write((const char *)cs_hash, sizeof(mpc_hash_t));
+    out.write((const char *)&H_size, sizeof(H_size));
+    out.write((const char *)&L_size, sizeof(L_size));
+
+    delta_g1.write_compressed(out);
+    delta_g2.write_compressed(out);
+    for (const G1 &h : H_g1) {
+        h.write_compressed(out);
+    }
+    for (const G1 &l : L_g1) {
+        l.write_compressed(out);
+    }
+}
+
 template<typename ppT>
 srs_mpc_phase2_accumulator<ppT> srs_mpc_phase2_accumulator<ppT>::read(
     std::istream &in)
@@ -103,6 +127,41 @@ srs_mpc_phase2_accumulator<ppT> srs_mpc_phase2_accumulator<ppT>::read(
     return accum;
 }
 
+template<typename ppT>
+srs_mpc_phase2_accumulator<ppT> srs_mpc_phase2_accumulator<
+    ppT>::read_compressed(std::istream &in)
+{
+    using G1 = libff::G1<ppT>;
+    using G2 = libff::G2<ppT>;
+
+    mpc_hash_t cs_hash;
+    size_t H_size;
+    size_t L_size;
+    in.read((char *)cs_hash, sizeof(mpc_hash_t));
+    in.read((char *)&H_size, sizeof(H_size));
+    in.read((char *)&L_size, sizeof(L_size));
+
+    G1 delta_g1;
+    G1::read_compressed(in, delta_g1);
+    G2 delta_g2;
+    G2::read_compressed(in, delta_g2);
+
+    libff::G1_vector<ppT> H_g1(H_size);
+    for (G1 &h : H_g1) {
+        G1::read_compressed(in, h);
+    }
+
+    libff::G1_vector<ppT> L_g1(L_size);
+    for (G1 &l : L_g1) {
+        G1::read_compressed(in, l);
+    }
+
+    srs_mpc_phase2_accumulator<ppT> l2(
+        cs_hash, delta_g1, delta_g2, std::move(H_g1), std::move(L_g1));
+    check_well_formed(l2, "mpc_layer2 (read)");
+    return l2;
+}
+
 template<typename ppT>
 srs_mpc_phase2_publickey<ppT>::srs_mpc_phase2_publickey(
     const mpc_hash_t transcript_digest,