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extractor.go
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extractor.go
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/*
* Copyright (C) 2017 The "MysteriumNetwork/node" Authors.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package identity
import (
"github.com/ethereum/go-ethereum/crypto"
"github.com/pkg/errors"
)
// Extractor is able to message signer's identity
type Extractor interface {
Extract(message []byte, signature Signature) (Identity, error)
}
// NewExtractor constructs Extractor instance
func NewExtractor() *extractor {
return &extractor{}
}
type extractor struct{}
// Extractor extracts identity which was used to sign given message
func (extractor *extractor) Extract(message []byte, signature Signature) (Identity, error) {
signatureBytes := signature.Bytes()
if len(signatureBytes) == 0 {
return Identity{}, errors.New("empty signature")
}
recoveredKey, err := crypto.Ecrecover(messageHash(message), signatureBytes)
if err != nil {
return Identity{}, err
}
key, err := crypto.UnmarshalPubkey(recoveredKey)
if err != nil {
return Identity{}, err
}
recoveredAddress := crypto.PubkeyToAddress(*key).Hex()
return FromAddress(recoveredAddress), nil
}