github.com/Unheilbar/quorum@v1.0.0/crypto/signature_nocgo.go (about)

     1  // Copyright 2017 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  //go:build nacl || js || !cgo
    18  // +build nacl js !cgo
    19  
    20  package crypto
    21  
    22  import (
    23  	"crypto/ecdsa"
    24  	"crypto/elliptic"
    25  	"errors"
    26  	"fmt"
    27  	"math/big"
    28  
    29  	"github.com/btcsuite/btcd/btcec"
    30  )
    31  
    32  // Ecrecover returns the uncompressed public key that created the given signature.
    33  func Ecrecover(hash, sig []byte) ([]byte, error) {
    34  	pub, err := SigToPub(hash, sig)
    35  	if err != nil {
    36  		return nil, err
    37  	}
    38  	bytes := (*btcec.PublicKey)(pub).SerializeUncompressed()
    39  	return bytes, err
    40  }
    41  
    42  // SigToPub returns the public key that created the given signature.
    43  func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
    44  	// Convert to btcec input format with 'recovery id' v at the beginning.
    45  	btcsig := make([]byte, SignatureLength)
    46  	btcsig[0] = sig[64] + 27
    47  	copy(btcsig[1:], sig)
    48  
    49  	pub, _, err := btcec.RecoverCompact(btcec.S256(), btcsig, hash)
    50  	return (*ecdsa.PublicKey)(pub), err
    51  }
    52  
    53  // Sign calculates an ECDSA signature.
    54  //
    55  // This function is susceptible to chosen plaintext attacks that can leak
    56  // information about the private key that is used for signing. Callers must
    57  // be aware that the given hash cannot be chosen by an adversery. Common
    58  // solution is to hash any input before calculating the signature.
    59  //
    60  // The produced signature is in the [R || S || V] format where V is 0 or 1.
    61  func Sign(hash []byte, prv *ecdsa.PrivateKey) ([]byte, error) {
    62  	if len(hash) != 32 {
    63  		return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(hash))
    64  	}
    65  	if prv.Curve != btcec.S256() {
    66  		return nil, fmt.Errorf("private key curve is not secp256k1")
    67  	}
    68  	sig, err := btcec.SignCompact(btcec.S256(), (*btcec.PrivateKey)(prv), hash, false)
    69  	if err != nil {
    70  		return nil, err
    71  	}
    72  	// Convert to Ethereum signature format with 'recovery id' v at the end.
    73  	v := sig[0] - 27
    74  	copy(sig, sig[1:])
    75  	sig[64] = v
    76  	return sig, nil
    77  }
    78  
    79  // VerifySignature checks that the given public key created signature over hash.
    80  // The public key should be in compressed (33 bytes) or uncompressed (65 bytes) format.
    81  // The signature should have the 64 byte [R || S] format.
    82  func VerifySignature(pubkey, hash, signature []byte) bool {
    83  	if len(signature) != 64 {
    84  		return false
    85  	}
    86  	sig := &btcec.Signature{R: new(big.Int).SetBytes(signature[:32]), S: new(big.Int).SetBytes(signature[32:])}
    87  	key, err := btcec.ParsePubKey(pubkey, btcec.S256())
    88  	if err != nil {
    89  		return false
    90  	}
    91  	// Reject malleable signatures. libsecp256k1 does this check but btcec doesn't.
    92  	if sig.S.Cmp(secp256k1halfN) > 0 {
    93  		return false
    94  	}
    95  	return sig.Verify(hash, key)
    96  }
    97  
    98  // DecompressPubkey parses a public key in the 33-byte compressed format.
    99  func DecompressPubkey(pubkey []byte) (*ecdsa.PublicKey, error) {
   100  	if len(pubkey) != 33 {
   101  		return nil, errors.New("invalid compressed public key length")
   102  	}
   103  	key, err := btcec.ParsePubKey(pubkey, btcec.S256())
   104  	if err != nil {
   105  		return nil, err
   106  	}
   107  	return key.ToECDSA(), nil
   108  }
   109  
   110  // CompressPubkey encodes a public key to the 33-byte compressed format.
   111  func CompressPubkey(pubkey *ecdsa.PublicKey) []byte {
   112  	return (*btcec.PublicKey)(pubkey).SerializeCompressed()
   113  }
   114  
   115  // S256 returns an instance of the secp256k1 curve.
   116  func S256() elliptic.Curve {
   117  	return btcec.S256()
   118  }