/
keypairs.go
219 lines (187 loc) · 4.41 KB
/
keypairs.go
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package security
import (
"errors"
"fmt"
"io"
"strconv"
"golang.org/x/crypto/nacl/box"
)
var (
ErrInvalidPublicKey = errors.New("invalid public key")
ErrInvalidPrivateKey = errors.New("invalid private key")
ErrInvalidNonce = errors.New("invalid nonce")
ErrMessageIntegrityFailed = errors.New("message integrity failed")
)
type KeyPairType byte
const (
Curve25519 KeyPairType = iota
)
func (t KeyPairType) PrivateKeySize() int {
switch t {
case Curve25519:
return 32
default:
panic(fmt.Sprintf("no private key size defined for key type %s", t))
}
}
func (t KeyPairType) PublicKeySize() int {
switch t {
case Curve25519:
return 32
default:
panic(fmt.Sprintf("no public key size defined for key type %s", t))
}
}
func (t KeyPairType) NonceSize() int {
switch t {
case Curve25519:
return 24
default:
return 0
}
}
func (t KeyPairType) String() string {
switch t {
case Curve25519:
return "curve25519"
default:
return strconv.Itoa(int(t))
}
}
func (t KeyPairType) checkNonceAndKeys(nonce, publicKey, privateKey []byte) error {
if len(publicKey) != t.PublicKeySize() {
return ErrInvalidPublicKey
}
if len(privateKey) != t.PrivateKeySize() {
return ErrInvalidPrivateKey
}
if len(nonce) != t.NonceSize() {
return ErrInvalidNonce
}
return nil
}
func (t KeyPairType) Seal(message, nonce, peersPublicKey, privateKey []byte) ([]byte, error) {
if err := t.checkNonceAndKeys(nonce, peersPublicKey, privateKey); err != nil {
return nil, err
}
switch t {
case Curve25519:
var (
pubKey, privKey [32]byte
n [24]byte
)
copy(n[:], nonce)
copy(pubKey[:], peersPublicKey)
copy(privKey[:], privateKey)
out := make([]byte, 0, len(message)+box.Overhead)
out = box.Seal(out, message, &n, &pubKey, &privKey)
return out, nil
default:
return nil, ErrInvalidKey
}
}
func (t KeyPairType) Open(message, nonce, peersPublicKey, privateKey []byte) ([]byte, error) {
if err := t.checkNonceAndKeys(nonce, peersPublicKey, privateKey); err != nil {
return nil, err
}
switch t {
case Curve25519:
var (
ok bool
pubKey, privKey [32]byte
n [24]byte
)
copy(n[:], nonce)
copy(pubKey[:], peersPublicKey)
copy(privKey[:], privateKey)
out := make([]byte, 0, len(message)-box.Overhead)
out, ok = box.Open(out, message, &n, &pubKey, &privKey)
if !ok {
return nil, ErrMessageIntegrityFailed
}
return out, nil
default:
return nil, ErrInvalidKey
}
}
func (t KeyPairType) Generate(randomReader io.Reader) (*ManagedKeyPair, error) {
switch t {
case Curve25519:
publicKey, privateKey, err := box.GenerateKey(randomReader)
if err != nil {
return nil, err
}
key := &ManagedKeyPair{
KeyPairType: t,
PrivateKey: privateKey[:],
PublicKey: publicKey[:],
}
return key, nil
default:
return nil, ErrInvalidKey
}
}
type ManagedKeyPair struct {
KeyPairType
IV []byte
PrivateKey []byte
EncryptedPrivateKey []byte
PublicKey []byte
}
func (k *ManagedKeyPair) Clone() ManagedKeyPair {
dup := func(v []byte) []byte {
if v == nil {
return nil
}
w := make([]byte, len(v))
copy(w, v)
return w
}
return ManagedKeyPair{
KeyPairType: k.KeyPairType,
IV: dup(k.IV),
PrivateKey: dup(k.PrivateKey),
EncryptedPrivateKey: dup(k.EncryptedPrivateKey),
PublicKey: dup(k.PublicKey),
}
}
func (k *ManagedKeyPair) Encrypted() bool { return k.EncryptedPrivateKey != nil }
func (k *ManagedKeyPair) Encrypt(keyKey *ManagedKey) error {
if keyKey.Encrypted() || k.Encrypted() {
return ErrKeyMustBeDecrypted
}
if k.IV == nil {
return ErrIVRequired
}
buf := k.PrivateKey
if k.PrivateKeySize()%keyKey.BlockSize() != 0 {
buf = keyKey.Pad(buf)
}
if err := keyKey.BlockCrypt(k.IV, keyKey.Plaintext, buf, true); err != nil {
return err
}
k.EncryptedPrivateKey = buf
k.PrivateKey = nil
return nil
}
func (k *ManagedKeyPair) Decrypt(keyKey *ManagedKey) error {
if keyKey.Encrypted() {
return ErrKeyMustBeDecrypted
}
if !k.Encrypted() {
return ErrKeyMustBeEncrypted
}
if k.IV == nil {
return ErrIVRequired
}
buf := k.EncryptedPrivateKey
if err := keyKey.BlockCrypt(k.IV, keyKey.Plaintext, buf, false); err != nil {
return fmt.Errorf("key-encrypting-key decrypt error: %s", err)
}
if k.PrivateKeySize()%keyKey.BlockSize() != 0 {
buf = keyKey.Unpad(buf)
}
k.PrivateKey = buf
k.EncryptedPrivateKey = nil
return nil
}