From 945798f913d5cabd79635f45045b680b02396bf9 Mon Sep 17 00:00:00 2001 From: Gustav Simonsson Date: Wed, 31 Dec 2014 15:39:33 +0100 Subject: [PATCH] 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 --- .gitignore | 5 + crypto/key.go | 205 ++++++++++++++++++++ crypto/key_store_passphrase_encryped.go | 244 ++++++++++++++++++++++++ crypto/key_store_plaintext_file.go | 113 +++++++++++ crypto/key_store_test.go | 118 ++++++++++++ 5 files changed, 685 insertions(+) create mode 100644 crypto/key.go create mode 100644 crypto/key_store_passphrase_encryped.go create mode 100644 crypto/key_store_plaintext_file.go create mode 100644 crypto/key_store_test.go diff --git a/.gitignore b/.gitignore index fea7df6c2d..f84fe60409 100644 --- a/.gitignore +++ b/.gitignore @@ -10,3 +10,8 @@ .DS_Store */**/.DS_Store .ethtest + +#* +.#* +*# +*~ diff --git a/crypto/key.go b/crypto/key.go new file mode 100644 index 0000000000..d4845ee226 --- /dev/null +++ b/crypto/key.go @@ -0,0 +1,205 @@ +/* + 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 . +*/ +/** + * @authors + * Gustav Simonsson + * @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 +} diff --git a/crypto/key_store_passphrase_encryped.go b/crypto/key_store_passphrase_encryped.go new file mode 100644 index 0000000000..b17536c3f4 --- /dev/null +++ b/crypto/key_store_passphrase_encryped.go @@ -0,0 +1,244 @@ +/* + 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 . +*/ +/** + * @authors + * Gustav Simonsson + * @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)] +} diff --git a/crypto/key_store_plaintext_file.go b/crypto/key_store_plaintext_file.go new file mode 100644 index 0000000000..7ca5e56791 --- /dev/null +++ b/crypto/key_store_plaintext_file.go @@ -0,0 +1,113 @@ +/* + 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 . +*/ +/** + * @authors + * Gustav Simonsson + * @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 +} diff --git a/crypto/key_store_test.go b/crypto/key_store_test.go new file mode 100644 index 0000000000..4127354447 --- /dev/null +++ b/crypto/key_store_test.go @@ -0,0 +1,118 @@ +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() +}