go-circom-prover-verifier/parsers.go

package gocircomprover

import (
	"encoding/hex"
	"fmt"
	"math/big"
	"strings"

	bn256 "github.com/ethereum/go-ethereum/crypto/bn256/cloudflare"
)

func stringToG1(h []string) (*bn256.G1, error) {
	if len(h) <= 2 {
		return nil, fmt.Errorf("not enought data for stringToG1")
	}
	h = h[:2]
	hexa := false
	if len(h[0]) > 1 {
		if "0x" == h[0][:2] {
			hexa = true
		}
	}
	in := ""

	var b []byte
	var err error
	if hexa {
		for i := range h {
			in += strings.TrimPrefix(h[i], "0x")
		}
		b, err = hex.DecodeString(in)
		if err != nil {
			return nil, err
		}
	} else {
		// TODO TMP
		// TODO use stringToBytes()
		if h[0] == "1" {
			h[0] = "0"
		}
		if h[1] == "1" {
			h[1] = "0"
		}
		bi0, ok := new(big.Int).SetString(h[0], 10)
		if !ok {
			return nil, fmt.Errorf("error parsing stringToG1")
		}
		bi1, ok := new(big.Int).SetString(h[1], 10)
		if !ok {
			return nil, fmt.Errorf("error parsing stringToG1")
		}
		b0 := bi0.Bytes()
		b1 := bi1.Bytes()
		if len(b0) != 32 {
			b0 = addZPadding(b0)
		}
		if len(b1) != 32 {
			b1 = addZPadding(b1)
		}

		b = append(b, b0...)
		b = append(b, b1...)
	}
	p := new(bn256.G1)
	_, err = p.Unmarshal(b)

	return p, err
}