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- // 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
- }
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