Release v0.1.0

vendor/github.com/muun/libwallet/challenge_public_key.go

@@ -0,0 +1,76 @@
+package libwallet
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/binary"
+
+	"github.com/btcsuite/btcd/btcec"
+	"github.com/btcsuite/btcutil/base58"
+	"github.com/pkg/errors"
+)
+
+type ChallengePublicKey struct {
+	pubKey *btcec.PublicKey
+}
+
+func NewChallengePublicKeyFromSerialized(serializedKey []byte) (*ChallengePublicKey, error) {
+
+	pubKey, err := btcec.ParsePubKey(serializedKey, btcec.S256())
+	if err != nil {
+		return nil, err
+	}
+
+	return &ChallengePublicKey{pubKey}, nil
+}
+
+func (k *ChallengePublicKey) EncryptKey(privKey *HDPrivateKey, recoveryCodeSalt []byte, birthday int) (string, error) {
+
+	const (
+		chainCodeStart = 13
+		chainCodeLength = 32
+		privKeyStart = 46
+		privKeyLength = 32
+	)
+
+	rawHDKey := base58.Decode(privKey.String())
+	plaintext := make([]byte, 0)
+	plaintext = append(plaintext, rawHDKey[privKeyStart:privKeyStart+privKeyLength]...)
+	plaintext = append(plaintext, rawHDKey[chainCodeStart:chainCodeStart+chainCodeLength]...)
+	if len(plaintext) != 64 {
+		return "", errors.Errorf("failed to encrypt key: expected payload of 64 bytes, found %v", len(plaintext))
+	}
+
+	privEph, err := btcec.NewPrivateKey(btcec.S256())
+	if err != nil {
+		return "", errors.Wrapf(err, "failed to encrypt key")
+	}
+
+	sharedSecret, _ := k.pubKey.ScalarMult(k.pubKey.X, k.pubKey.Y, privEph.D.Bytes())
+	serializedPubkey := privEph.PubKey().SerializeCompressed()
+	iv := serializedPubkey[len(serializedPubkey)-aes.BlockSize:]
+
+	block, err := aes.NewCipher(sharedSecret.Bytes())
+	if err != nil {
+		return "", err
+	}
+
+	ciphertext := make([]byte, len(plaintext))
+
+	mode := cipher.NewCBCEncrypter(block, iv)
+	mode.CryptBlocks(ciphertext, plaintext)
+
+	birthdayBytes := make([]byte, 2)
+	binary.BigEndian.PutUint16(birthdayBytes, uint16(birthday))
+
+	result := make([]byte, 0, 1+2+33+len(ciphertext)+len(recoveryCodeSalt))
+	buf := bytes.NewBuffer(result)
+	buf.WriteByte(2)
+	buf.Write(birthdayBytes)
+	buf.Write(privEph.PubKey().SerializeCompressed())
+	buf.Write(ciphertext)
+	buf.Write(recoveryCodeSalt)
+
+	return base58.Encode(buf.Bytes()), nil
+}