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Add new key_store interface and two new key stores 

* Add new generic key_store interface
* Add new plaintext key store storing unprotected keys on disk
* Add new encrypted key store storing encrypted keys on disk
* Add new entropy mixing function using OS and go runtime sources
This commit is contained in:
Gustav Simonsson 2014-12-31 15:39:33 +01:00
parent bb55307a9d
commit 945798f913
5 changed files with 685 additions and 0 deletions
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5
.gitignore vendored
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@ -10,3 +10,8 @@
.DS_Store .DS_Store
*/**/.DS_Store */**/.DS_Store
.ethtest .ethtest
#*
.#*
*#
*~

205
crypto/key.go Normal file
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/*
This file is part of go-ethereum
go-ethereum 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.
go-ethereum 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 Lesser General Public License
along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @authors
* Gustav Simonsson <gustav.simonsson@gmail.com>
* @date 2015
*
*/
package crypto
import (
"bytes"
"code.google.com/p/go-uuid/uuid"
"crypto/ecdsa"
"crypto/elliptic"
crand "crypto/rand"
"encoding/binary"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"io"
"os"
"runtime"
"strings"
"time"
)
type Key struct {
Id *uuid.UUID // Version 4 "random" for unique id not derived from key data
Flags [4]byte // RFU
// we only store privkey as pubkey/address can be derived from it
// privkey in this struct is always in plaintext
PrivateKey *ecdsa.PrivateKey
}
type KeyPlainJSON struct {
Id string
Flags string
PrivateKey string
}
type CipherJSON struct {
Salt string
IV string
CipherText string
}
type KeyProtectedJSON struct {
Id string
Flags string
Crypto CipherJSON
}
func (k *Key) Address() []byte {
pubBytes := FromECDSAPub(&k.PrivateKey.PublicKey)
return Sha3(pubBytes)[12:]
}
func (k *Key) MarshalJSON() (j []byte, err error) {
stringStruct := KeyPlainJSON{
k.Id.String(),
hex.EncodeToString(k.Flags[:]),
hex.EncodeToString(FromECDSA(k.PrivateKey)),
}
j, _ = json.Marshal(stringStruct)
return
}
func (k *Key) UnmarshalJSON(j []byte) (err error) {
keyJSON := new(KeyPlainJSON)
err = json.Unmarshal(j, &keyJSON)
if err != nil {
return
}
u := new(uuid.UUID)
*u = uuid.Parse(keyJSON.Id)
if *u == nil {
err = errors.New("UUID parsing failed")
return
}
k.Id = u
flagsBytes, err := hex.DecodeString(keyJSON.Flags)
if err != nil {
return
}
PrivateKeyBytes, err := hex.DecodeString(keyJSON.PrivateKey)
if err != nil {
return
}
copy(k.Flags[:], flagsBytes[0:4])
k.PrivateKey = ToECDSA(PrivateKeyBytes)
return
}
func NewKey() *Key {
randBytes := GetEntropyCSPRNG(32)
reader := bytes.NewReader(randBytes)
_, x, y, err := elliptic.GenerateKey(S256(), reader)
if err != nil {
panic("key generation: elliptic.GenerateKey failed: " + err.Error())
}
privateKeyMarshalled := elliptic.Marshal(S256(), x, y)
privateKeyECDSA := ToECDSA(privateKeyMarshalled)
key := new(Key)
id := uuid.NewRandom()
key.Id = &id
// flags := new([4]byte)
// key.Flags = flags
key.PrivateKey = privateKeyECDSA
return key
}
// plain crypto/rand. this is /dev/urandom on Unix-like systems.
func GetEntropyCSPRNG(n int) []byte {
mainBuff := make([]byte, n)
_, err := io.ReadFull(crand.Reader, mainBuff)
if err != nil {
panic("key generation: reading from crypto/rand failed: " + err.Error())
}
return mainBuff
}
// TODO: verify. Do not use until properly discussed.
// we start with crypt/rand, then mix in additional sources of entropy.
// These sources are from three types: OS, go runtime and ethereum client state.
func GetEntropyTinFoilHat() []byte {
startTime := time.Now().UnixNano()
// for each source, we XOR in it's SHA3 hash.
mainBuff := GetEntropyCSPRNG(32)
// 1. OS entropy sources
startTimeBytes := make([]byte, 32)
binary.PutVarint(startTimeBytes, startTime)
startTimeHash := Sha3(startTimeBytes)
mix32Byte(mainBuff, startTimeHash)
pid := os.Getpid()
pidBytes := make([]byte, 32)
binary.PutUvarint(pidBytes, uint64(pid))
pidHash := Sha3(pidBytes)
mix32Byte(mainBuff, pidHash)
osEnv := os.Environ()
osEnvBytes := []byte(strings.Join(osEnv, ""))
osEnvHash := Sha3(osEnvBytes)
mix32Byte(mainBuff, osEnvHash)
// not all OS have hostname in env variables
osHostName, err := os.Hostname()
if err != nil {
osHostNameBytes := []byte(osHostName)
osHostNameHash := Sha3(osHostNameBytes)
mix32Byte(mainBuff, osHostNameHash)
}
// 2. go runtime entropy sources
memStats := new(runtime.MemStats)
runtime.ReadMemStats(memStats)
memStatsBytes := []byte(fmt.Sprintf("%v", memStats))
memStatsHash := Sha3(memStatsBytes)
mix32Byte(mainBuff, memStatsHash)
// 3. Mix in ethereum / client state
// TODO: list of network peers structs (IP, port, etc)
// TODO: merkle patricia tree root hash for world state and tx list
// 4. Yo dawg we heard you like entropy so we'll grab some entropy from how
// long it took to grab the above entropy. And a yield, for good measure.
runtime.Gosched()
diffTime := time.Now().UnixNano() - startTime
diffTimeBytes := make([]byte, 32)
binary.PutVarint(diffTimeBytes, diffTime)
diffTimeHash := Sha3(diffTimeBytes)
mix32Byte(mainBuff, diffTimeHash)
return mainBuff
}
func mix32Byte(buff []byte, mixBuff []byte) []byte {
for i := 0; i < 32; i++ {
buff[i] ^= mixBuff[i]
}
return buff
}

244
crypto/key_store_passphrase_encryped.go Normal file
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/*
This file is part of go-ethereum
go-ethereum 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.
go-ethereum 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 Lesser General Public License
along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @authors
* Gustav Simonsson <gustav.simonsson@gmail.com>
* @date 2015
*
*/
/*
This key store behaves as KeyStorePlaintextFile with the difference that
the private key is encrypted and encoded as a JSON object within the
key JSON object.
Cryptography:
1. Encryption key is scrypt derived key from user passphrase. Scrypt parameters
(work factors) [1][2] are defined as constants below.
2. Scrypt salt is 32 random bytes from CSPRNG. It is appended to ciphertext.
3. Checksum is SHA3 of the private key bytes.
4. Plaintext is concatenation of private key bytes and checksum.
5. Encryption algo is AES 256 CBC [3][4]
6. CBC IV is 16 random bytes from CSPRNG. It is appended to ciphertext.
7. Plaintext padding is PKCS #7 [5][6]
Encoding:
1. On disk, ciphertext, salt and IV are encoded as a JSON object.
cat a key file to see the structure.
2. byte arrays are ASCII HEX encoded as JSON strings.
3. The EC private key bytes are in uncompressed form [7].
They are a big-endian byte slice of the absolute value of D [8][9].
4. The checksum is the last 32 bytes of the plaintext byte array and the
private key is the preceeding bytes.
References:
1. http://www.tarsnap.com/scrypt/scrypt-slides.pdf
2. http://stackoverflow.com/questions/11126315/what-are-optimal-scrypt-work-factors
3. http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
4. http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher-block_chaining_.28CBC.29
5. https://leanpub.com/gocrypto/read#leanpub-auto-block-cipher-modes
6. http://tools.ietf.org/html/rfc2315
7. http://bitcoin.stackexchange.com/questions/3059/what-is-a-compressed-bitcoin-key
8. http://golang.org/pkg/crypto/ecdsa/#PrivateKey
9. https://golang.org/pkg/math/big/#Int.Bytes
*/
package crypto
import (
"bytes"
"code.google.com/p/go-uuid/uuid"
"code.google.com/p/go.crypto/scrypt"
"crypto/aes"
"crypto/cipher"
"encoding/hex"
"encoding/json"
"errors"
"os"
"path"
)
const scryptN int = 262144 // 2^18
const scryptr int = 8
const scryptp int = 1
const scryptdkLen int = 32
type KeyStorePassphrase struct {
keysDirPath string
}
func (ks KeyStorePassphrase) GenerateNewKey(auth string) (key *Key, err error) {
key, err = GenerateNewKeyDefault(ks, auth)
return
}
func (ks KeyStorePassphrase) GetKey(keyId *uuid.UUID, auth string) (key *Key, err error) {
keyBytes, flags, err := DecryptKey(ks, keyId, auth)
key = new(Key)
key.Id = keyId
copy(key.Flags[:], flags[0:4])
key.PrivateKey = ToECDSA(keyBytes)
return
}
func (ks KeyStorePassphrase) StoreKey(key *Key, auth string) (err error) {
authArray := []byte(auth)
salt := GetEntropyCSPRNG(32)
derivedKey, err := scrypt.Key(authArray, salt, scryptN, scryptr, scryptp, scryptdkLen)
if err != nil {
return
}
keyBytes := FromECDSA(key.PrivateKey)
keyBytesHash := Sha3(keyBytes)
toEncrypt := PKCS7Pad(append(keyBytes, keyBytesHash...))
AES256Block, err := aes.NewCipher(derivedKey)
if err != nil {
return
}
iv := GetEntropyCSPRNG(aes.BlockSize) // 16
AES256CBCEncrypter := cipher.NewCBCEncrypter(AES256Block, iv)
cipherText := make([]byte, len(toEncrypt))
AES256CBCEncrypter.CryptBlocks(cipherText, toEncrypt)
cipherStruct := CipherJSON{
hex.EncodeToString(salt),
hex.EncodeToString(iv),
hex.EncodeToString(cipherText),
}
keyStruct := KeyProtectedJSON{
key.Id.String(),
hex.EncodeToString(key.Flags[:]),
cipherStruct,
}
keyJSON, err := json.Marshal(keyStruct)
if err != nil {
return
}
err = WriteKeyFile(key.Id.String(), ks.keysDirPath, keyJSON)
return
}
func (ks KeyStorePassphrase) DeleteKey(keyId *uuid.UUID, auth string) (err error) {
// only delete if correct passphrase is given
_, _, err = DecryptKey(ks, keyId, auth)
if err != nil {
return
}
keyDirPath := path.Join(ks.keysDirPath, keyId.String())
err = os.RemoveAll(keyDirPath)
return
}
func DecryptKey(ks KeyStorePassphrase, keyId *uuid.UUID, auth string) (keyBytes []byte, flags []byte, err error) {
fileContent, err := GetKeyFile(ks.keysDirPath, keyId)
if err != nil {
return
}
keyProtected := new(KeyProtectedJSON)
err = json.Unmarshal(fileContent, keyProtected)
flags, err = hex.DecodeString(keyProtected.Flags)
if err != nil {
return
}
salt, err := hex.DecodeString(keyProtected.Crypto.Salt)
if err != nil {
return
}
iv, err := hex.DecodeString(keyProtected.Crypto.IV)
if err != nil {
return
}
cipherText, err := hex.DecodeString(keyProtected.Crypto.CipherText)
if err != nil {
return
}
authArray := []byte(auth)
derivedKey, err := scrypt.Key(authArray, salt, scryptN, scryptr, scryptp, scryptdkLen)
if err != nil {
return
}
AES256Block, err := aes.NewCipher(derivedKey)
if err != nil {
return
}
AES256CBCDecrypter := cipher.NewCBCDecrypter(AES256Block, iv)
paddedPlainText := make([]byte, len(cipherText))
AES256CBCDecrypter.CryptBlocks(paddedPlainText, cipherText)
plainText := PKCS7Unpad(paddedPlainText)
if plainText == nil {
err = errors.New("Decryption failed: PKCS7Unpad failed after decryption")
return
}
keyBytes = plainText[:len(plainText)-32]
keyBytesHash := plainText[len(plainText)-32:]
if !bytes.Equal(Sha3(keyBytes), keyBytesHash) {
err = errors.New("Decryption failed: checksum mismatch")
return
}
return keyBytes, flags, 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)]
}

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crypto/key_store_plaintext_file.go Normal file
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/*
This file is part of go-ethereum
go-ethereum 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.
go-ethereum 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 Lesser General Public License
along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @authors
* Gustav Simonsson <gustav.simonsson@gmail.com>
* @date 2015
*
*/
package crypto
import (
"code.google.com/p/go-uuid/uuid"
"encoding/json"
"fmt"
"io/ioutil"
"os"
"os/user"
"path"
)
// TODO: rename to KeyStore when replacing existing KeyStore
type KeyStore2 interface {
GenerateNewKey(string) (*Key, error) // create and store new key, optionally using auth string
GetKey(*uuid.UUID, string) (*Key, error) // key from id and auth string
StoreKey(*Key, string) error // store key optionally using auth string
DeleteKey(*uuid.UUID, string) error // delete key by id and auth string
}
type KeyStorePlaintext struct {
keysDirPath string
}
// TODO: copied from cmd/ethereum/flags.go
func DefaultDataDir() string {
usr, _ := user.Current()
return path.Join(usr.HomeDir, ".ethereum")
}
func (ks KeyStorePlaintext) GenerateNewKey(auth string) (key *Key, err error) {
key, err = GenerateNewKeyDefault(ks, auth)
return
}
func GenerateNewKeyDefault(ks KeyStore2, auth string) (key *Key, err error) {
defer func() {
if r := recover(); r != nil {
err = fmt.Errorf("GenerateNewKey error: %v", r)
}
}()
key = NewKey()
err = ks.StoreKey(key, auth)
return
}
func (ks KeyStorePlaintext) GetKey(keyId *uuid.UUID, auth string) (key *Key, err error) {
fileContent, err := GetKeyFile(ks.keysDirPath, keyId)
if err != nil {
return
}
key = new(Key)
err = json.Unmarshal(fileContent, key)
return
}
func (ks KeyStorePlaintext) StoreKey(key *Key, auth string) (err error) {
keyJSON, err := json.Marshal(key)
if err != nil {
return
}
err = WriteKeyFile(key.Id.String(), ks.keysDirPath, keyJSON)
return
}
func (ks KeyStorePlaintext) DeleteKey(keyId *uuid.UUID, auth string) (err error) {
keyDirPath := path.Join(ks.keysDirPath, keyId.String())
err = os.RemoveAll(keyDirPath)
return
}
func GetKeyFile(keysDirPath string, keyId *uuid.UUID) (fileContent []byte, err error) {
idString := keyId.String()
keyDirPath := path.Join(keysDirPath, idString)
keyFilePath := path.Join(keyDirPath, idString)
fileContent, err = ioutil.ReadFile(keyFilePath)
return
}
func WriteKeyFile(idString string, keysDirPath string, content []byte) (err error) {
keyDirPath := path.Join(keysDirPath, idString)
keyFilePath := path.Join(keyDirPath, idString)
err = os.MkdirAll(keyDirPath, 0700) // read, write and dir search for user
if err != nil {
return
}
err = ioutil.WriteFile(keyFilePath, content, 0600) // read, write for user
return
}

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crypto/key_store_test.go Normal file
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package crypto
import (
"fmt"
"reflect"
"testing"
)
func TestKeyStorePlaintext(t *testing.T) {
ks := new(KeyStorePlaintext)
ks.keysDirPath = DefaultDataDir()
pass := "" // not used but required by API
k1, err := ks.GenerateNewKey(pass)
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
k2 := new(Key)
k2, err = ks.GetKey(k1.Id, pass)
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
if !reflect.DeepEqual(k1.Id, k2.Id) {
fmt.Println("key Id mismatch")
t.FailNow()
}
if k1.Flags != k2.Flags {
fmt.Println("key Flags mismatch")
t.FailNow()
}
if !reflect.DeepEqual(k1.PrivateKey, k2.PrivateKey) {
fmt.Println("key PrivateKey mismatch")
t.FailNow()
}
err = ks.DeleteKey(k2.Id, pass)
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
}
func TestKeyStorePassphrase(t *testing.T) {
ks := new(KeyStorePassphrase)
ks.keysDirPath = DefaultDataDir()
pass := "foo"
k1, err := ks.GenerateNewKey(pass)
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
k2 := new(Key)
k2, err = ks.GetKey(k1.Id, pass)
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
if !reflect.DeepEqual(k1.Id, k2.Id) {
fmt.Println("key Id mismatch")
t.FailNow()
}
if k1.Flags != k2.Flags {
fmt.Println("key Flags mismatch")
t.FailNow()
}
if !reflect.DeepEqual(k1.PrivateKey, k2.PrivateKey) {
fmt.Println("key PrivateKey mismatch")
t.FailNow()
}
err = ks.DeleteKey(k2.Id, pass) // also to clean up created files
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
}
func TestKeyStorePassphraseDecryptionFail(t *testing.T) {
ks := new(KeyStorePassphrase)
ks.keysDirPath = DefaultDataDir()
pass := "foo"
k1, err := ks.GenerateNewKey(pass)
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
_, err = ks.GetKey(k1.Id, "bar") // wrong passphrase
// fmt.Println(err.Error())
if err == nil {
t.FailNow()
}
err = ks.DeleteKey(k1.Id, "bar") // wrong passphrase
if err == nil {
fmt.Println(err.Error())
t.FailNow()
}
err = ks.DeleteKey(k1.Id, pass) // to clean up
if err != nil {
fmt.Println(err.Error())
t.FailNow()
}
}
func TestKeyMixedEntropy(t *testing.T) {
GetEntropyTinFoilHat()
}