github.com/codingfuture/orig-energi3@v0.8.4/swarm/storage/feed/sign.go (about)

     1  // Copyright 2018 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package feed
    18  
    19  import (
    20  	"crypto/ecdsa"
    21  
    22  	"github.com/ethereum/go-ethereum/common"
    23  	"github.com/ethereum/go-ethereum/crypto"
    24  )
    25  
    26  const signatureLength = 65
    27  
    28  // Signature is an alias for a static byte array with the size of a signature
    29  type Signature [signatureLength]byte
    30  
    31  // Signer signs feed update payloads
    32  type Signer interface {
    33  	Sign(common.Hash) (Signature, error)
    34  	Address() common.Address
    35  }
    36  
    37  // GenericSigner implements the Signer interface
    38  // It is the vanilla signer that probably should be used in most cases
    39  type GenericSigner struct {
    40  	PrivKey *ecdsa.PrivateKey
    41  	address common.Address
    42  }
    43  
    44  // NewGenericSigner builds a signer that will sign everything with the provided private key
    45  func NewGenericSigner(privKey *ecdsa.PrivateKey) *GenericSigner {
    46  	return &GenericSigner{
    47  		PrivKey: privKey,
    48  		address: crypto.PubkeyToAddress(privKey.PublicKey),
    49  	}
    50  }
    51  
    52  // Sign signs the supplied data
    53  // It wraps the ethereum crypto.Sign() method
    54  func (s *GenericSigner) Sign(data common.Hash) (signature Signature, err error) {
    55  	signaturebytes, err := crypto.Sign(data.Bytes(), s.PrivKey)
    56  	if err != nil {
    57  		return
    58  	}
    59  	copy(signature[:], signaturebytes)
    60  	return
    61  }
    62  
    63  // Address returns the public key of the signer's private key
    64  func (s *GenericSigner) Address() common.Address {
    65  	return s.address
    66  }
    67  
    68  // getUserAddr extracts the address of the feed update signer
    69  func getUserAddr(digest common.Hash, signature Signature) (common.Address, error) {
    70  	pub, err := crypto.SigToPub(digest.Bytes(), signature[:])
    71  	if err != nil {
    72  		return common.Address{}, err
    73  	}
    74  	return crypto.PubkeyToAddress(*pub), nil
    75  }