/
presale.go
134 lines (123 loc) · 3.95 KB
/
presale.go
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// This file is part of the go-sberex library. The go-sberex 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-sberex 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 <http://www.gnu.org/licenses/> for more details.
package keystore
import (
"crypto/aes"
"crypto/cipher"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"github.com/Sberex/go-sberex/accounts"
"github.com/Sberex/go-sberex/crypto"
"github.com/pborman/uuid"
"golang.org/x/crypto/pbkdf2"
)
// creates a Key and stores that in the given KeyStore by decrypting a presale key JSON
func importPreSaleKey(keyStore keyStore, keyJSON []byte, password string) (accounts.Account, *Key, error) {
key, err := decryptPreSaleKey(keyJSON, password)
if err != nil {
return accounts.Account{}, nil, err
}
key.Id = uuid.NewRandom()
a := accounts.Account{Address: key.Address, URL: accounts.URL{Scheme: KeyStoreScheme, Path: keyStore.JoinPath(keyFileName(key.Address))}}
err = keyStore.StoreKey(a.URL.Path, key, password)
return a, 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)
if err != nil {
return nil, errors.New("invalid hex in encSeed")
}
if len(encSeedBytes) < 16 {
return nil, errors.New("invalid encSeed, too short")
}
iv := encSeedBytes[:16]
cipherText := encSeedBytes[16:]
/*
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)
if err != nil {
return nil, err
}
ethPriv := crypto.Keccak256(plainText)
ecKey := crypto.ToECDSAUnsafe(ethPriv)
key = &Key{
Id: nil,
Address: crypto.PubkeyToAddress(ecKey.PublicKey),
PrivateKey: ecKey,
}
derivedAddr := hex.EncodeToString(key.Address.Bytes()) // needed because .Hex() gives leading "0x"
expectedAddr := preSaleKeyStruct.EthAddr
if derivedAddr != expectedAddr {
err = fmt.Errorf("decrypted addr '%s' not equal to expected addr '%s'", derivedAddr, expectedAddr)
}
return key, err
}
func aesCTRXOR(key, inText, iv []byte) ([]byte, error) {
// AES-128 is selected due to size of encryptKey.
aesBlock, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
stream := cipher.NewCTR(aesBlock, iv)
outText := make([]byte, len(inText))
stream.XORKeyStream(outText, inText)
return outText, err
}
func aesCBCDecrypt(key, cipherText, iv []byte) ([]byte, error) {
aesBlock, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
decrypter := cipher.NewCBCDecrypter(aesBlock, iv)
paddedPlaintext := make([]byte, len(cipherText))
decrypter.CryptBlocks(paddedPlaintext, cipherText)
plaintext := pkcs7Unpad(paddedPlaintext)
if plaintext == nil {
return nil, ErrDecrypt
}
return plaintext, err
}
// From https://leanpub.com/gocrypto/read#leanpub-auto-block-cipher-modes
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)]
}