Add json SRS parsers compatible with eth official impl

README.md

@@ -1,11 +1,18 @@
 # eth-kzg-ceremony-alt
 
-Alternative (non-official) implementation in Go of the *contributor* for the Ethereum KZG Trusted Setup Ceremony.
+Alternative (non-official) implementation in Go of the *contributor* for the [Ethereum KZG Trusted Setup Ceremony](https://github.com/ethereum/kzg-ceremony/blob/main/FAQ.md).
 
 The purpose of this repo is to use it to contribute to the upcoming Ethereum KZG Trusted Setup Ceremony, without using the official implementation.
 
-This implementation has been done without checking the other impls code (nor the python reference neither the rust impl), in order to not be biased by that code.
+The Ceremony is considered safe as long as there is at least one honest participant, with the idea that if you participate, assuming that you consider yourself honest, you can consider the Ceremony safe.
+Probably most of the contributions will be generated with the same code (official impl, which has been audited). The idea of this repo is to try to bring more diversity to the table with another independent implementation.
+
+This implementation has been done without looking at the other impls code (neither the python reference nor the rust impl (except for the points parsers test vectors)), in order to not be biased by that code.
 
 > This code has not been audited, use it at your own risk.
 
 Why in Go? Ideally would have done this code using Rust & arkworks, but the official impl already uses that.
+
+Documents used for this implementation:
+- [KZG10-Ceremony-audit-report.pdf, section *3.1 Overview of PoT ceremonies*](https://github.com/ethereum/kzg-ceremony/blob/main/KZG10-Ceremony-audit-report.pdf)
+- [*Why and how zkSNARKs work*, by Maksym Petkus](https://arxiv.org/abs/1906.07221v1)

parsers.go

@@ -0,0 +1,61 @@
+package kzgceremony
+
+import (
+	"encoding/hex"
+	"strings"
+
+	bls12381 "github.com/kilic/bls12-381"
+)
+
+// WIP
+
+// ParseEthJSON parses the eth-kzg-ceremony SRS json format
+func ParseEthJSON(g1sStr, g2sStr []string) (*SRS, error) {
+	g1 := bls12381.NewG1()
+	g2 := bls12381.NewG2()
+	nG1s := len(g1sStr)
+	nG2s := len(g2sStr)
+	g1s := make([]*bls12381.PointG1, nG1s)
+	g2s := make([]*bls12381.PointG2, nG2s)
+	for i := 0; i < nG1s; i++ {
+		g1sBytes, err := hex.DecodeString(strings.TrimPrefix(g1sStr[i], "0x"))
+		if err != nil {
+			return nil, err
+		}
+		g1s_i, err := g1.FromCompressed(g1sBytes)
+		if err != nil {
+			return nil, err
+		}
+		g1s[i] = g1s_i
+	}
+	for i := 0; i < nG2s; i++ {
+		g2sBytes, err := hex.DecodeString(strings.TrimPrefix(g2sStr[i], "0x"))
+		if err != nil {
+			return nil, err
+		}
+		g2s_i, err := g2.FromCompressed(g2sBytes)
+		if err != nil {
+			return nil, err
+		}
+		g2s[i] = g2s_i
+	}
+	return &SRS{G1s: g1s, G2s: g2s}, nil
+}
+
+// ToEthJSON outputs the SRS into the eth-kzg-ceremony SRS json format
+func (srs *SRS) ToEthJSON() ([]string, []string, error) {
+	g1 := bls12381.NewG1()
+	g2 := bls12381.NewG2()
+	nG1s := len(srs.G1s)
+	nG2s := len(srs.G2s)
+	g1s := make([]string, nG1s)
+	g2s := make([]string, nG2s)
+
+	for i := 0; i < nG1s; i++ {
+		g1s[i] = "0x" + hex.EncodeToString(g1.ToCompressed(srs.G1s[i]))
+	}
+	for i := 0; i < nG2s; i++ {
+		g2s[i] = "0x" + hex.EncodeToString(g2.ToCompressed(srs.G2s[i]))
+	}
+	return g1s, g2s, nil
+}

parsers_test.go

@@ -0,0 +1,118 @@
+package kzgceremony
+
+import (
+	"encoding/hex"
+	"strings"
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	bls12381 "github.com/kilic/bls12-381"
+)
+
+func TestParseSRS(t *testing.T) {
+	c := qt.New(t)
+
+	srs_0 := newEmptySRS(2, 2)
+
+	contr_1, err := Contribute(srs_0, []byte("1111111111111111111111111111111111111111111111111111111111111111"))
+	c.Assert(err, qt.IsNil)
+
+	g1s, g2s, err := contr_1.SRS.ToEthJSON()
+	c.Assert(err, qt.IsNil)
+
+	parsedSRS, err := ParseEthJSON(g1s, g2s)
+	c.Assert(err, qt.IsNil)
+
+	g1 := bls12381.NewG1()
+	g2 := bls12381.NewG2()
+	for i := 0; i < len(contr_1.SRS.G1s); i++ {
+		c.Assert(g1.Equal(parsedSRS.G1s[i], contr_1.SRS.G1s[i]), qt.IsTrue)
+	}
+	for i := 0; i < len(contr_1.SRS.G2s); i++ {
+		c.Assert(g2.Equal(parsedSRS.G2s[i], contr_1.SRS.G2s[i]), qt.IsTrue)
+	}
+}
+
+func TestParseCompressedG1Point(t *testing.T) {
+	// this test is just to check that github.com/kilic/bls12-381 is
+	// compatible with the compressed points from zkcrypto/bls12-381
+	c := qt.New(t)
+
+	g1 := bls12381.NewG1()
+
+	p1Str := "0x97f1d3a73197d7942695638c4fa9ac0fc3688c4f9774b905a14e3a3f171bac586c55e83ff97a1aeffb3af00adb22c6bb"
+	g1Bytes, err := hex.DecodeString(strings.TrimPrefix(p1Str, "0x"))
+	g1Point, err := g1.FromCompressed(g1Bytes)
+	c.Assert(err, qt.IsNil)
+
+	recompressed := g1.ToCompressed(g1Point)
+	c.Assert("0x"+hex.EncodeToString(recompressed), qt.Equals, p1Str)
+
+	p1Str = "0xc00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+	g1Bytes, err = hex.DecodeString(strings.TrimPrefix(p1Str, "0x"))
+	g1Point, err = g1.FromCompressed(g1Bytes)
+	c.Assert(err, qt.IsNil)
+
+	recompressed = g1.ToCompressed(g1Point)
+	c.Assert("0x"+hex.EncodeToString(recompressed), qt.Equals, p1Str)
+	// additionally check that g1Point is zero
+	c.Assert(g1.Equal(g1Point, g1.Zero()), qt.IsTrue)
+}
+
+func TestParseCompressedG2Point(t *testing.T) {
+	// this test is just to check that github.com/kilic/bls12-381 is
+	// compatible with the compressed points from zkcrypto/bls12-381
+	c := qt.New(t)
+
+	g2 := bls12381.NewG2()
+
+	p2Str := "0x93e02b6052719f607dacd3a088274f65596bd0d09920b61ab5da61bbdc7f5049334cf11213945d57e5ac7d055d042b7e024aa2b2f08f0a91260805272dc51051c6e47ad4fa403b02b4510b647ae3d1770bac0326a805bbefd48056c8c121bdb8"
+	g2Bytes, err := hex.DecodeString(strings.TrimPrefix(p2Str, "0x"))
+	g2Point, err := g2.FromCompressed(g2Bytes)
+	c.Assert(err, qt.IsNil)
+
+	recompressed := g2.ToCompressed(g2Point)
+	c.Assert("0x"+hex.EncodeToString(recompressed), qt.Equals, p2Str)
+
+	p2Str = "0xc00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+	g2Bytes, err = hex.DecodeString(strings.TrimPrefix(p2Str, "0x"))
+	g2Point, err = g2.FromCompressed(g2Bytes)
+	c.Assert(err, qt.IsNil)
+
+	recompressed = g2.ToCompressed(g2Point)
+	c.Assert("0x"+hex.EncodeToString(recompressed), qt.Equals, p2Str)
+	// additionally check that g1Point is zero
+	c.Assert(g2.Equal(g2Point, g2.Zero()), qt.IsTrue)
+}
+
+func TestVectorFromRustImpl(t *testing.T) {
+	c := qt.New(t)
+	testVectorG1s := []string{
+		"0x97f1d3a73197d7942695638c4fa9ac0fc3688c4f9774b905a14e3a3f171bac586c55e83ff97a1aeffb3af00adb22c6bb",
+		"0xae4a5e0fe4947fd5551664fc49453d805ce6af2dd6f053e147d95d9ede825190b06028f228f47c0d3118b71313235aa7",
+		"0x888a1073366b3e974c318be5862f607c18fb5241cfefc3c8b82c31c4db10f866c546804db6e44bf61b61d8c31d006099",
+		"0x84afca7ce5cc42aa998725610d14cd47078e523a9cb96b66856f563d62d44ff6489f0b1827b853e94d9474b75a138ec6",
+		"0x8ae778a5b534c6eadcce4c4e7dd1dab3674d20bfe686f70506fba1695bbdae2455169b035505e5246d726a9e0c982335",
+	}
+	testVectorG2s := []string{
+		"0x93e02b6052719f607dacd3a088274f65596bd0d09920b61ab5da61bbdc7f5049334cf11213945d57e5ac7d055d042b7e024aa2b2f08f0a91260805272dc51051c6e47ad4fa403b02b4510b647ae3d1770bac0326a805bbefd48056c8c121bdb8",
+		"0xa5d4fc7bfa882ef674fbbcdda73c66c2627a5a723ddf6fc0f242b3f71301a6e7181708a8c63756787a2c3e47c2b347ca18c64b103461036830880cd26bacad80cdbfe00c69e9214b7c90bf30ab0804f520bed3ce608aefeb6f85011f0d745575",
+		"0x87b93440866545adf37f5119d640036b2856a790bd09c2b7f69a1a1bdc7846c5f48f622fcbf5c46a51dede46a4682b7b118542548df17ff7c7e6f63049e1d1c56ca1a637f8a55136d0ed7ab466e78550f635dc06d78d87a3003dab133b8e275a",
+	}
+
+	parsedSRS, err := ParseEthJSON(testVectorG1s, testVectorG2s)
+	c.Assert(err, qt.IsNil)
+
+	g1s, g2s, err := parsedSRS.ToEthJSON()
+	c.Assert(err, qt.IsNil)
+
+	c.Assert(len(testVectorG1s), qt.Equals, len(g1s))
+	c.Assert(len(testVectorG2s), qt.Equals, len(g2s))
+
+	for i := 0; i < len(g1s); i++ {
+		c.Assert(g1s[i], qt.Equals, testVectorG1s[i])
+	}
+	for i := 0; i < len(g2s); i++ {
+		c.Assert(g2s[i], qt.Equals, testVectorG2s[i])
+	}
+}