1package common
 2
 3import (
 4	"encoding/hex"
 5	"math/big"
 6
 7	ethCommon "github.com/ethereum/go-ethereum/common"
 8	"github.com/hermeznetwork/tracerr"
 9	"github.com/iden3/go-iden3-crypto/babyjub"
10)
11
12// SwapEndianness swaps the order of the bytes in the slice.
13func SwapEndianness(b []byte) []byte {
14	o := make([]byte, len(b))
15	for i := range b {
16		o[len(b)-1-i] = b[i]
17	}
18	return o
19}
20
21// EthAddrToBigInt returns a *big.Int from a given ethereum common.Address.
22func EthAddrToBigInt(a ethCommon.Address) *big.Int {
23	return new(big.Int).SetBytes(a.Bytes())
24}
25
26// BJJFromStringWithChecksum parses a hex string in Hermez format (which has
27// the Hermez checksum at the last byte, and is encoded in BigEndian) and
28// returns the corresponding *babyjub.PublicKey. This method is not part of the
29// spec, is used for importing javascript test vectors data.
30func BJJFromStringWithChecksum(s string) (babyjub.PublicKeyComp, error) {
31	b, err := hex.DecodeString(s)
32	if err != nil {
33		return EmptyBJJComp, tracerr.Wrap(err)
34	}
35	pkBytes := SwapEndianness(b)
36	var pkComp babyjub.PublicKeyComp
37	copy(pkComp[:], pkBytes[:])
38	return pkComp, nil
39}
40
41// CopyBigInt returns a copy of the big int
42func CopyBigInt(a *big.Int) *big.Int {
43	return new(big.Int).SetBytes(a.Bytes())
44}