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- // Copyright 2017 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/>.
- // +build !nacl,!js,cgo
- package crypto
- import (
- "crypto/ecdsa"
- "crypto/elliptic"
- "fmt"
- "github.com/ethereum/go-ethereum/common/math"
- "github.com/ethereum/go-ethereum/crypto/secp256k1"
- )
- // Ecrecover returns the uncompressed public key that created the given signature.
- func Ecrecover(hash, sig []byte) ([]byte, error) {
- return secp256k1.RecoverPubkey(hash, sig)
- }
- // SigToPub returns the public key that created the given signature.
- func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
- s, err := Ecrecover(hash, sig)
- if err != nil {
- return nil, err
- }
- x, y := elliptic.Unmarshal(S256(), s)
- return &ecdsa.PublicKey{Curve: S256(), X: x, Y: y}, nil
- }
- // Sign calculates an ECDSA signature.
- //
- // This function is susceptible to chosen plaintext attacks that can leak
- // information about the private key that is used for signing. Callers must
- // be aware that the given digest cannot be chosen by an adversery. Common
- // solution is to hash any input before calculating the signature.
- //
- // The produced signature is in the [R || S || V] format where V is 0 or 1.
- func Sign(digestHash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
- if len(digestHash) != DigestLength {
- return nil, fmt.Errorf("hash is required to be exactly %d bytes (%d)", DigestLength, len(digestHash))
- }
- seckey := math.PaddedBigBytes(prv.D, prv.Params().BitSize/8)
- defer zeroBytes(seckey)
- return secp256k1.Sign(digestHash, seckey)
- }
- // VerifySignature checks that the given public key created signature over digest.
- // The public key should be in compressed (33 bytes) or uncompressed (65 bytes) format.
- // The signature should have the 64 byte [R || S] format.
- func VerifySignature(pubkey, digestHash, signature []byte) bool {
- return secp256k1.VerifySignature(pubkey, digestHash, signature)
- }
- // DecompressPubkey parses a public key in the 33-byte compressed format.
- func DecompressPubkey(pubkey []byte) (*ecdsa.PublicKey, error) {
- x, y := secp256k1.DecompressPubkey(pubkey)
- if x == nil {
- return nil, fmt.Errorf("invalid public key")
- }
- return &ecdsa.PublicKey{X: x, Y: y, Curve: S256()}, nil
- }
- // CompressPubkey encodes a public key to the 33-byte compressed format.
- func CompressPubkey(pubkey *ecdsa.PublicKey) []byte {
- return secp256k1.CompressPubkey(pubkey.X, pubkey.Y)
- }
- // S256 returns an instance of the secp256k1 curve.
- func S256() elliptic.Curve {
- return secp256k1.S256()
- }
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