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/
key.go
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/
key.go
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// Package crypto implements various cryptographic utilities used by libp2p.
// This includes a Public and Private key interface and key implementations
// for supported key algorithms.
package crypto
import (
"crypto/elliptic"
"crypto/hmac"
"crypto/rand"
"crypto/sha1"
"crypto/sha512"
"crypto/subtle"
"encoding/base64"
"errors"
"fmt"
"hash"
"io"
pb "github.com/libp2p/go-libp2p-core/crypto/pb"
"github.com/gogo/protobuf/proto"
"github.com/minio/sha256-simd"
)
const (
// RSA is an enum for the supported RSA key type
RSA = iota
// Ed25519 is an enum for the supported Ed25519 key type
Ed25519
// Secp256k1 is an enum for the supported Secp256k1 key type
Secp256k1
// ECDSA is an enum for the supported ECDSA key type
ECDSA
)
var (
// ErrBadKeyType is returned when a key is not supported
ErrBadKeyType = errors.New("invalid or unsupported key type")
// KeyTypes is a list of supported keys
KeyTypes = []int{
RSA,
Ed25519,
Secp256k1,
ECDSA,
}
)
// PubKeyUnmarshaller is a func that creates a PubKey from a given slice of bytes
type PubKeyUnmarshaller func(data []byte) (PubKey, error)
// PrivKeyUnmarshaller is a func that creates a PrivKey from a given slice of bytes
type PrivKeyUnmarshaller func(data []byte) (PrivKey, error)
// PubKeyUnmarshallers is a map of unmarshallers by key type
var PubKeyUnmarshallers = map[pb.KeyType]PubKeyUnmarshaller{
pb.KeyType_RSA: UnmarshalRsaPublicKey,
pb.KeyType_Ed25519: UnmarshalEd25519PublicKey,
pb.KeyType_Secp256k1: UnmarshalSecp256k1PublicKey,
pb.KeyType_ECDSA: UnmarshalECDSAPublicKey,
}
// PrivKeyUnmarshallers is a map of unmarshallers by key type
var PrivKeyUnmarshallers = map[pb.KeyType]PrivKeyUnmarshaller{
pb.KeyType_RSA: UnmarshalRsaPrivateKey,
pb.KeyType_Ed25519: UnmarshalEd25519PrivateKey,
pb.KeyType_Secp256k1: UnmarshalSecp256k1PrivateKey,
pb.KeyType_ECDSA: UnmarshalECDSAPrivateKey,
}
// Key represents a crypto key that can be compared to another key
type Key interface {
// Equals checks whether two PubKeys are the same
Equals(Key) bool
// Raw returns the raw bytes of the key (not wrapped in the
// libp2p-crypto protobuf).
//
// This function is the inverse of {Priv,Pub}KeyUnmarshaler.
Raw() ([]byte, error)
// Type returns the protobuf key type.
Type() pb.KeyType
}
// PrivKey represents a private key that can be used to generate a public key and sign data
type PrivKey interface {
Key
// Cryptographically sign the given bytes
Sign([]byte) ([]byte, error)
// Return a public key paired with this private key
GetPublic() PubKey
}
// PubKey is a public key that can be used to verifiy data signed with the corresponding private key
type PubKey interface {
Key
// Verify that 'sig' is the signed hash of 'data'
Verify(data []byte, sig []byte) (bool, error)
}
// GenSharedKey generates the shared key from a given private key
type GenSharedKey func([]byte) ([]byte, error)
// GenerateKeyPair generates a private and public key
func GenerateKeyPair(typ, bits int) (PrivKey, PubKey, error) {
return GenerateKeyPairWithReader(typ, bits, rand.Reader)
}
// GenerateKeyPairWithReader returns a keypair of the given type and bitsize
func GenerateKeyPairWithReader(typ, bits int, src io.Reader) (PrivKey, PubKey, error) {
switch typ {
case RSA:
return GenerateRSAKeyPair(bits, src)
case Ed25519:
return GenerateEd25519Key(src)
case Secp256k1:
return GenerateSecp256k1Key(src)
case ECDSA:
return GenerateECDSAKeyPair(src)
default:
return nil, nil, ErrBadKeyType
}
}
// GenerateEKeyPair returns an ephemeral public key and returns a function that will compute
// the shared secret key. Used in the identify module.
//
// Focuses only on ECDH now, but can be made more general in the future.
func GenerateEKeyPair(curveName string) ([]byte, GenSharedKey, error) {
var curve elliptic.Curve
switch curveName {
case "P-256":
curve = elliptic.P256()
case "P-384":
curve = elliptic.P384()
case "P-521":
curve = elliptic.P521()
default:
return nil, nil, fmt.Errorf("unknown curve name")
}
priv, x, y, err := elliptic.GenerateKey(curve, rand.Reader)
if err != nil {
return nil, nil, err
}
pubKey := elliptic.Marshal(curve, x, y)
done := func(theirPub []byte) ([]byte, error) {
// Verify and unpack node's public key.
x, y := elliptic.Unmarshal(curve, theirPub)
if x == nil {
return nil, fmt.Errorf("malformed public key: %d %v", len(theirPub), theirPub)
}
if !curve.IsOnCurve(x, y) {
return nil, errors.New("invalid public key")
}
// Generate shared secret.
secret, _ := curve.ScalarMult(x, y, priv)
return secret.Bytes(), nil
}
return pubKey, done, nil
}
// StretchedKeys ...
type StretchedKeys struct {
IV []byte
MacKey []byte
CipherKey []byte
}
// PENDING DEPRECATION: KeyStretcher() will be deprecated with secio; for new
// code, please use PBKDF2 (golang.org/x/crypto/pbkdf2) instead.
// KeyStretcher returns a set of keys for each party by stretching the shared key.
// (myIV, theirIV, myCipherKey, theirCipherKey, myMACKey, theirMACKey).
// This function accepts the following cipher types:
// - AES-128
// - AES-256
// The function will panic upon receiving an unknown cipherType
func KeyStretcher(cipherType string, hashType string, secret []byte) (StretchedKeys, StretchedKeys) {
var cipherKeySize int
var ivSize int
switch cipherType {
case "AES-128":
ivSize = 16
cipherKeySize = 16
case "AES-256":
ivSize = 16
cipherKeySize = 32
default:
panic("Unrecognized cipher, programmer error?")
}
hmacKeySize := 20
seed := []byte("key expansion")
result := make([]byte, 2*(ivSize+cipherKeySize+hmacKeySize))
var h func() hash.Hash
switch hashType {
case "SHA1":
h = sha1.New
case "SHA256":
h = sha256.New
case "SHA512":
h = sha512.New
default:
panic("Unrecognized hash function, programmer error?")
}
m := hmac.New(h, secret)
// note: guaranteed to never return an error
m.Write(seed)
a := m.Sum(nil)
j := 0
for j < len(result) {
m.Reset()
// note: guaranteed to never return an error.
m.Write(a)
m.Write(seed)
b := m.Sum(nil)
todo := len(b)
if j+todo > len(result) {
todo = len(result) - j
}
copy(result[j:j+todo], b)
j += todo
m.Reset()
// note: guaranteed to never return an error.
m.Write(a)
a = m.Sum(nil)
}
half := len(result) / 2
r1 := result[:half]
r2 := result[half:]
var k1 StretchedKeys
var k2 StretchedKeys
k1.IV = r1[0:ivSize]
k1.CipherKey = r1[ivSize : ivSize+cipherKeySize]
k1.MacKey = r1[ivSize+cipherKeySize:]
k2.IV = r2[0:ivSize]
k2.CipherKey = r2[ivSize : ivSize+cipherKeySize]
k2.MacKey = r2[ivSize+cipherKeySize:]
return k1, k2
}
// UnmarshalPublicKey converts a protobuf serialized public key into its
// representative object
func UnmarshalPublicKey(data []byte) (PubKey, error) {
pmes := new(pb.PublicKey)
err := proto.Unmarshal(data, pmes)
if err != nil {
return nil, err
}
return PublicKeyFromProto(pmes)
}
// PublicKeyFromProto converts an unserialized protobuf PublicKey message
// into its representative object.
func PublicKeyFromProto(pmes *pb.PublicKey) (PubKey, error) {
um, ok := PubKeyUnmarshallers[pmes.GetType()]
if !ok {
return nil, ErrBadKeyType
}
data := pmes.GetData()
pk, err := um(data)
if err != nil {
return nil, err
}
switch tpk := pk.(type) {
case *RsaPublicKey:
tpk.cached, _ = pmes.Marshal()
}
return pk, nil
}
// MarshalPublicKey converts a public key object into a protobuf serialized
// public key
func MarshalPublicKey(k PubKey) ([]byte, error) {
pbmes, err := PublicKeyToProto(k)
if err != nil {
return nil, err
}
return proto.Marshal(pbmes)
}
// PublicKeyToProto converts a public key object into an unserialized
// protobuf PublicKey message.
func PublicKeyToProto(k PubKey) (*pb.PublicKey, error) {
pbmes := new(pb.PublicKey)
pbmes.Type = k.Type()
data, err := k.Raw()
if err != nil {
return nil, err
}
pbmes.Data = data
return pbmes, nil
}
// UnmarshalPrivateKey converts a protobuf serialized private key into its
// representative object
func UnmarshalPrivateKey(data []byte) (PrivKey, error) {
pmes := new(pb.PrivateKey)
err := proto.Unmarshal(data, pmes)
if err != nil {
return nil, err
}
um, ok := PrivKeyUnmarshallers[pmes.GetType()]
if !ok {
return nil, ErrBadKeyType
}
return um(pmes.GetData())
}
// MarshalPrivateKey converts a key object into its protobuf serialized form.
func MarshalPrivateKey(k PrivKey) ([]byte, error) {
pbmes := new(pb.PrivateKey)
pbmes.Type = k.Type()
data, err := k.Raw()
if err != nil {
return nil, err
}
pbmes.Data = data
return proto.Marshal(pbmes)
}
// ConfigDecodeKey decodes from b64 (for config file) to a byte array that can be unmarshalled.
func ConfigDecodeKey(b string) ([]byte, error) {
return base64.StdEncoding.DecodeString(b)
}
// ConfigEncodeKey encodes a marshalled key to b64 (for config file).
func ConfigEncodeKey(b []byte) string {
return base64.StdEncoding.EncodeToString(b)
}
// KeyEqual checks whether two Keys are equivalent (have identical byte representations).
func KeyEqual(k1, k2 Key) bool {
if k1 == k2 {
return true
}
return k1.Equals(k2)
}
func basicEquals(k1, k2 Key) bool {
if k1.Type() != k2.Type() {
return false
}
a, err := k1.Raw()
if err != nil {
return false
}
b, err := k2.Raw()
if err != nil {
return false
}
return subtle.ConstantTimeCompare(a, b) == 1
}