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package crypto
import (
"crypto/aes"
"crypto/cipher"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/sha256"
"fmt"
"encoding/hex"
"encoding/json"
"errors"
"code.google.com/p/go-uuid/uuid"
"code.google.com/p/go.crypto/pbkdf2"
"code.google.com/p/go.crypto/ripemd160"
"github.com/ethereum/go-ethereum/crypto/secp256k1"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/ethutil"
"github.com/obscuren/ecies"
)
func init() {
// specify the params for the s256 curve
ecies.AddParamsForCurve(S256(), ecies.ECIES_AES128_SHA256)
}
func Sha3(data []byte) []byte {
d := sha3.NewKeccak256()
d.Write(data)
return d.Sum(nil)
}
// Creates an ethereum address given the bytes and the nonce
func CreateAddress(b []byte, nonce uint64) []byte {
return Sha3(ethutil.NewValue([]interface{}{b, nonce}).Encode())[12:]
}
func Sha256(data []byte) []byte {
hash := sha256.Sum256(data)
return hash[:]
}
func Ripemd160(data []byte) []byte {
ripemd := ripemd160.New()
ripemd.Write(data)
return ripemd.Sum(nil)
}
func Ecrecover(data []byte) []byte {
var in = struct {
hash []byte
sig []byte
}{data[:32], data[32:]}
r, _ := secp256k1.RecoverPubkey(in.hash, in.sig)
return r
}
// New methods using proper ecdsa keys from the stdlib
func ToECDSA(prv []byte) *ecdsa.PrivateKey {
if len(prv) == 0 {
return nil
}
priv := new(ecdsa.PrivateKey)
priv.PublicKey.Curve = S256()
priv.D = ethutil.BigD(prv)
priv.PublicKey.X, priv.PublicKey.Y = S256().ScalarBaseMult(prv)
return priv
}
func FromECDSA(prv *ecdsa.PrivateKey) []byte {
if prv == nil {
return nil
}
return prv.D.Bytes()
}
func ToECDSAPub(pub []byte) *ecdsa.PublicKey {
if len(pub) == 0 {
return nil
}
x, y := elliptic.Unmarshal(S256(), pub)
return &ecdsa.PublicKey{S256(), x, y}
}
func FromECDSAPub(pub *ecdsa.PublicKey) []byte {
if pub == nil {
return nil
}
return elliptic.Marshal(S256(), pub.X, pub.Y)
}
func GenerateKey() (*ecdsa.PrivateKey, error) {
return ecdsa.GenerateKey(S256(), rand.Reader)
}
func SigToPub(hash, sig []byte) *ecdsa.PublicKey {
s := Ecrecover(append(hash, sig...))
x, y := elliptic.Unmarshal(S256(), s)
return &ecdsa.PublicKey{S256(), x, y}
}
func Sign(hash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
if len(hash) != 32 {
return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(hash))
}
sig, err = secp256k1.Sign(hash, ethutil.LeftPadBytes(prv.D.Bytes(), prv.Params().BitSize/8))
return
}
func Encrypt(pub *ecdsa.PublicKey, message []byte) ([]byte, error) {
return ecies.Encrypt(rand.Reader, ecies.ImportECDSAPublic(pub), message, nil, nil)
}
func Decrypt(prv *ecdsa.PrivateKey, ct []byte) ([]byte, error) {
key := ecies.ImportECDSA(prv)
return key.Decrypt(rand.Reader, ct, nil, nil)
}
// creates a Key and stores that in the given KeyStore by decrypting a presale key JSON
func ImportPreSaleKey(keyStore KeyStore2, keyJSON []byte, password string) (*Key, error) {
key, err := decryptPreSaleKey(keyJSON, password)
if err != nil {
return nil, err
}
key.Id = uuid.NewRandom()
err = keyStore.StoreKey(key, password)
return key, err
}
func decryptPreSaleKey(fileContent []byte, password string) (key *Key, err error) {
preSaleKeyStruct := struct {
EncSeed string
EthAddr string
Email string
BtcAddr string
}{}
err = json.Unmarshal(fileContent, &preSaleKeyStruct)
if err != nil {
return nil, err
}
encSeedBytes, err := hex.DecodeString(preSaleKeyStruct.EncSeed)
iv := encSeedBytes[:16]
cipherText := encSeedBytes[16:]
/*
See https://github.com/ethereum/pyethsaletool
pyethsaletool generates the encryption key from password by
2000 rounds of PBKDF2 with HMAC-SHA-256 using password as salt (:().
16 byte key length within PBKDF2 and resulting key is used as AES key
*/
passBytes := []byte(password)
derivedKey := pbkdf2.Key(passBytes, passBytes, 2000, 16, sha256.New)
plainText, err := aesCBCDecrypt(derivedKey, cipherText, iv)
ethPriv := Sha3(plainText)
ecKey := ToECDSA(ethPriv)
key = &Key{
Id: nil,
Address: PubkeyToAddress(ecKey.PublicKey),
PrivateKey: ecKey,
}
derivedAddr := ethutil.Bytes2Hex(key.Address)
expectedAddr := preSaleKeyStruct.EthAddr
if derivedAddr != expectedAddr {
err = errors.New("decrypted addr not equal to expected addr")
}
return key, err
}
func aesCBCDecrypt(key []byte, cipherText []byte, iv []byte) (plainText []byte, err error) {
aesBlock, err := aes.NewCipher(key)
if err != nil {
return plainText, err
}
decrypter := cipher.NewCBCDecrypter(aesBlock, iv)
paddedPlainText := make([]byte, len(cipherText))
decrypter.CryptBlocks(paddedPlainText, cipherText)
plainText = PKCS7Unpad(paddedPlainText)
if plainText == nil {
err = errors.New("Decryption failed: PKCS7Unpad failed after decryption")
}
return plainText, err
}
// From https://leanpub.com/gocrypto/read#leanpub-auto-block-cipher-modes
func PKCS7Pad(in []byte) []byte {
padding := 16 - (len(in) % 16)
if padding == 0 {
padding = 16
}
for i := 0; i < padding; i++ {
in = append(in, byte(padding))
}
return in
}
func PKCS7Unpad(in []byte) []byte {
if len(in) == 0 {
return nil
}
padding := in[len(in)-1]
if int(padding) > len(in) || padding > aes.BlockSize {
return nil
} else if padding == 0 {
return nil
}
for i := len(in) - 1; i > len(in)-int(padding)-1; i-- {
if in[i] != padding {
return nil
}
}
return in[:len(in)-int(padding)]
}
func PubkeyToAddress(p ecdsa.PublicKey) []byte {
pubBytes := FromECDSAPub(&p)
return Sha3(pubBytes[1:])[12:]
}
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