From 701f21aaba610fec86c3720d6e16419e6d145743 Mon Sep 17 00:00:00 2001
From: Shelly Wei <guaichen07@gmail.com>
Date: Mon, 2 Dec 2019 16:52:15 -0800
Subject: [PATCH 1/2] move crypto related code to common/crypto

---
 crypto/crypto.go      | 121 +++++++++++++++++++++++++++++++++++++++++-
 crypto/crypto_test.go |   4 +-
 2 files changed, 122 insertions(+), 3 deletions(-)

diff --git a/crypto/crypto.go b/crypto/crypto.go
index 7e38866..7661573 100644
--- a/crypto/crypto.go
+++ b/crypto/crypto.go
@@ -1,10 +1,18 @@
 package crypto
 
 import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
 	"encoding/base64"
+	"errors"
+	"io"
+	"strings"
 
 	"github.com/gogo/protobuf/proto"
 	ic "github.com/libp2p/go-libp2p-core/crypto"
+	"github.com/libp2p/go-libp2p-core/peer"
 )
 
 func Sign(key ic.PrivKey, channelMessage proto.Message) ([]byte, error) {
@@ -34,6 +42,117 @@ func ToPrivKey(privKey string) (ic.PrivKey, error) {
 }
 
 // public key string to ic.PubKey interface
-func ToPubKey(pubKey []byte) (ic.PubKey, error) {
+func ToPubKey(pubKey string) (ic.PubKey, error) {
+	raw, err := base64.StdEncoding.DecodeString(pubKey)
+	if err != nil {
+		return nil, err
+	}
+	return ic.UnmarshalSecp256k1PublicKey(raw)
+}
+
+// Secp256k1 private key string to ic.PrivKey interface
+func ToPrivKeyRaw(privKey []byte) (ic.PrivKey, error) {
+	return ic.UnmarshalSecp256k1PrivateKey(privKey)
+}
+
+// public key string to ic.PubKey interface
+func ToPubKeyRaw(pubKey []byte) (ic.PubKey, error) {
 	return ic.UnmarshalSecp256k1PublicKey(pubKey)
 }
+
+func GenKeyPairs() (ic.PrivKey, ic.PubKey, error) {
+	return ic.GenerateSecp256k1Key(rand.Reader)
+}
+
+func addBase64Padding(text []byte) string {
+	value := string(text)
+	m := len(value) % 4
+	if m != 0 {
+		value += strings.Repeat("=", 4-m)
+	}
+
+	return value
+}
+
+func removeBase64Padding(value string) string {
+	return strings.Replace(value, "=", "", -1)
+}
+
+// pkcs7 padding
+func Pad(src []byte) []byte {
+	padding := aes.BlockSize - len(src)%aes.BlockSize
+	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
+	return append(src, padtext...)
+}
+
+func Unpad(src []byte) ([]byte, error) {
+	length := len(src)
+	unpadding := int(src[length-1])
+
+	if unpadding > length {
+		return nil, errors.New("unpad error. This could happen when incorrect encryption key is used")
+	}
+
+	return src[:(length - unpadding)], nil
+}
+
+func Encrypt(key, text []byte) (string, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", err
+	}
+
+	msg := Pad(text)
+	ciphertext := make([]byte, aes.BlockSize+len(msg))
+	iv := ciphertext[:aes.BlockSize]
+	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+		return "", err
+	}
+
+	cfb := cipher.NewCFBEncrypter(block, iv)
+	cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(msg))
+	finalMsg := removeBase64Padding(base64.URLEncoding.EncodeToString(ciphertext))
+	return finalMsg, nil
+}
+
+func Decrypt(key, text []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	decodedMsg, err := base64.URLEncoding.DecodeString(addBase64Padding(text))
+	if err != nil {
+		return nil, err
+	}
+
+	if (len(decodedMsg) % aes.BlockSize) != 0 {
+		return nil, errors.New("blocksize must be multiple of decoded message length")
+	}
+
+	iv := decodedMsg[:aes.BlockSize]
+	msg := decodedMsg[aes.BlockSize:]
+
+	cfb := cipher.NewCFBDecrypter(block, iv)
+	cfb.XORKeyStream(msg, msg)
+
+	unpadMsg, err := Unpad(msg)
+	if err != nil {
+		return nil, err
+	}
+
+	return unpadMsg, nil
+}
+
+func getPubKeyFromPeerId(pid string) (ic.PubKey, error) {
+	peerId, err := peer.IDB58Decode(pid)
+	if err != nil {
+		return nil, err
+	}
+	pubKey, err2 := peerId.ExtractPublicKey()
+	if err2 != nil {
+		return nil, err2
+	}
+	return pubKey, nil
+}
+
diff --git a/crypto/crypto_test.go b/crypto/crypto_test.go
index 69b35aa..f37b30d 100644
--- a/crypto/crypto_test.go
+++ b/crypto/crypto_test.go
@@ -23,9 +23,9 @@ func TestSignVerify(t *testing.T) {
 		t.Error("get raw public key from privKey failed")
 		return
 	}
-	pubKey, err := ToPubKey(rawPubKey)
+	pubKey, err := ToPubKeyRaw(rawPubKey)
 	if err != nil {
-		t.Error("ToPubKey failed")
+		t.Error("ToPubKeyRaw failed")
 		return
 	}
 

From a7ad774644588ae3e52ff60bd5e2365beb13c662 Mon Sep 17 00:00:00 2001
From: Shelly Wei <guaichen07@gmail.com>
Date: Mon, 2 Dec 2019 16:57:30 -0800
Subject: [PATCH 2/2] add test

---
 crypto/crypto_test.go | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/crypto/crypto_test.go b/crypto/crypto_test.go
index f37b30d..b09e4ff 100644
--- a/crypto/crypto_test.go
+++ b/crypto/crypto_test.go
@@ -8,6 +8,7 @@ import (
 
 const (
 	KeyString = "CAISIJFNZZd5ZSvi9OlJP/mz/vvUobvlrr2//QN4DzX/EShP"
+	EncryptKey = "Tron2theMoon1234"
 )
 
 func TestSignVerify(t *testing.T) {
@@ -44,3 +45,13 @@ func TestSignVerify(t *testing.T) {
 		t.Error("Verify with public key failed")
 	}
 }
+
+func TestEncryptDecrypt(t *testing.T) {
+	origin := "Hello World"
+	key := []byte(EncryptKey)
+	encryptMsg, _ := Encrypt(key, []byte(origin))
+	msg, _ := Decrypt(key, []byte(encryptMsg))
+	if string(msg) != origin {
+		t.Errorf("Decrypt failed")
+	}
+}