46 lines
1.4 KiB
Go
46 lines
1.4 KiB
Go
// Copyright 2020 The go-ethereum Authors
|
|
// This file is part of the go-ethereum library.
|
|
//
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public License
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
package bls12381
|
|
|
|
import (
|
|
"errors"
|
|
"math/big"
|
|
|
|
"github.com/ethereum/go-ethereum/common"
|
|
)
|
|
|
|
func bigFromHex(hex string) *big.Int {
|
|
return new(big.Int).SetBytes(common.FromHex(hex))
|
|
}
|
|
|
|
// decodeFieldElement expects 64 byte input with zero top 16 bytes,
|
|
// returns lower 48 bytes.
|
|
func decodeFieldElement(in []byte) ([]byte, error) {
|
|
if len(in) != 64 {
|
|
return nil, errors.New("invalid field element length")
|
|
}
|
|
// check top bytes
|
|
for i := 0; i < 16; i++ {
|
|
if in[i] != byte(0x00) {
|
|
return nil, errors.New("invalid field element top bytes")
|
|
}
|
|
}
|
|
out := make([]byte, 48)
|
|
copy(out[:], in[16:])
|
|
return out, nil
|
|
}
|