From 2a0eae897556239e2df4c7a14d26a9730f56344c Mon Sep 17 00:00:00 2001
From: zhangxinxiang <zhangxinxiang@sz-sess.com>
Date: Tue, 18 Jun 2019 04:07:35 +0800
Subject: [PATCH] gaes encryption and decryption add CFB mode

---
 g/crypto/gaes/gaes.go      | 63 ++++++++++++++++++++++++++++++++++++++
 g/crypto/gaes/gaes_test.go | 22 +++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/g/crypto/gaes/gaes.go b/g/crypto/gaes/gaes.go
index 14f34f44b..40d381f9f 100644
--- a/g/crypto/gaes/gaes.go
+++ b/g/crypto/gaes/gaes.go
@@ -98,3 +98,66 @@ func PKCS5UnPadding(src []byte, blockSize int) ([]byte, error) {
 
     return src[:(length - unpadding)], nil
 }
+
+/**
+ * AES加密, 使用CFB模式.
+ * 注意key必须为16/24/32位长度，padding返回补位长度，iv初始化向量为非必需参数
+ * author: zseeker
+ * date: 2019-06-18
+ */
+func EncryptCFB(plainText []byte, key []byte, padding *int, iv ...[]byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	blockSize := block.BlockSize()
+	plainText, *padding = ZeroPadding(plainText, blockSize) //补位0
+	ivValue   := ([]byte)(nil)
+	if len(iv) > 0 {
+		ivValue = iv[0]
+	} else {
+		ivValue = []byte(ivDefValue)
+	}
+	stream := cipher.NewCFBEncrypter(block, ivValue)
+	cipherText := make([]byte, len(plainText))
+	stream.XORKeyStream(cipherText, plainText)
+	return cipherText, nil
+}
+
+/**
+ * AES解密, 使用CFB模式.
+ * 注意key必须为16/24/32位长度，unpadding为去补位长度，iv初始化向量为非必需参数
+ * author: zseeker
+ * date: 2019-06-18
+ */
+func DecryptCFB(cipherText []byte, key []byte, unpadding int, iv ...[]byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+	if len(cipherText) < aes.BlockSize {
+		return nil, errors.New("cipherText too short")
+	}
+	ivValue   := ([]byte)(nil)
+	if len(iv) > 0 {
+		ivValue = iv[0]
+	} else {
+		ivValue = []byte(ivDefValue)
+	}
+	stream := cipher.NewCFBDecrypter(block, ivValue)
+	plainText := make([]byte, len(cipherText))
+	stream.XORKeyStream(plainText, cipherText)
+	plainText = ZeroUnPadding(plainText, unpadding) //去补位0
+	return plainText, nil
+}
+
+func ZeroPadding(ciphertext []byte, blockSize int) ([]byte, int) {
+	padding := blockSize - len(ciphertext)%blockSize
+	padtext := bytes.Repeat([]byte{byte(0)}, padding)
+	return append(ciphertext, padtext...), padding
+}
+
+func ZeroUnPadding(plaintext []byte, unpadding int) []byte {
+	length := len(plaintext)
+	return plaintext[:(length - unpadding)]
+}
\ No newline at end of file
diff --git a/g/crypto/gaes/gaes_test.go b/g/crypto/gaes/gaes_test.go
index 57f307a6e..119900065 100644
--- a/g/crypto/gaes/gaes_test.go
+++ b/g/crypto/gaes/gaes_test.go
@@ -32,6 +32,10 @@ var (
 	keys       = []byte("12345678912345678912345678912346")
 	key_err    = []byte("1234")
 	key_32_err = []byte("1234567891234567891234567891234 ")
+
+	// cfb模式blockSize补位长度, add by zseeker
+	padding_size      = 16 - len(content)
+	content_16_cfb, _ = gbase64.Decode("oSmget3aBDT1nJnBp8u6kA==")
 )
 
 func TestEncrypt(t *testing.T) {
@@ -125,3 +129,21 @@ func TestPKCS5UnPaddingErr(t *testing.T) {
 		gtest.AssertNE(err, nil)
 	})
 }
+
+func TestEncryptCFB(t *testing.T) {
+	gtest.Case(t, func() {
+		var padding int = 0
+		data, err := gaes.EncryptCFB(content, key_16, &padding, iv)
+		gtest.Assert(err, nil)
+		gtest.Assert(padding, padding_size)
+		gtest.Assert(data, []byte(content_16_cfb))
+	})
+}
+
+func TestDecryptCFB(t *testing.T) {
+	gtest.Case(t, func() {
+		decrypt, err := gaes.DecryptCFB([]byte(content_16_cfb), key_16, padding_size, iv)
+		gtest.Assert(err, nil)
+		gtest.Assert(decrypt, content)
+	})
+}