publish lancet

cryptor/des.go

@@ -0,0 +1,166 @@
+// Copyright 2021 dudaodong@gmail.com. All rights reserved.
+// Use of this source code is governed by MIT license
+
+// Package cryptor implements some util functions to encrypt and decrypt.
+package cryptor
+
+import (
+	"bytes"
+	"crypto/cipher"
+	"crypto/des"
+	"crypto/rand"
+	"io"
+)
+
+// DesEcbEncrypt encrypt data with key use DES ECB algorithm
+// len(key) should be 8
+func DesEcbEncrypt(data, key []byte) []byte {
+	cipher, _ := des.NewCipher(generateDesKey(key))
+	length := (len(data) + des.BlockSize) / des.BlockSize
+	plain := make([]byte, length*des.BlockSize)
+	copy(plain, data)
+	pad := byte(len(plain) - len(data))
+	for i := len(data); i < len(plain); i++ {
+		plain[i] = pad
+	}
+	encrypted := make([]byte, len(plain))
+	for bs, be := 0, cipher.BlockSize(); bs <= len(data); bs, be = bs+cipher.BlockSize(), be+cipher.BlockSize() {
+		cipher.Encrypt(encrypted[bs:be], plain[bs:be])
+	}
+
+	return encrypted
+}
+
+// DesEcbDecrypt decrypt data with key use DES ECB algorithm
+// len(key) should be 8
+func DesEcbDecrypt(encrypted, key []byte) []byte {
+	cipher, _ := des.NewCipher(generateDesKey(key))
+	decrypted := make([]byte, len(encrypted))
+	//
+	for bs, be := 0, cipher.BlockSize(); bs < len(encrypted); bs, be = bs+cipher.BlockSize(), be+cipher.BlockSize() {
+		cipher.Decrypt(decrypted[bs:be], encrypted[bs:be])
+	}
+
+	trim := 0
+	if len(decrypted) > 0 {
+		trim = len(decrypted) - int(decrypted[len(decrypted)-1])
+	}
+
+	return decrypted[:trim]
+}
+
+// DesCbcEncrypt encrypt data with key use DES CBC algorithm
+// len(key) should be 8
+func DesCbcEncrypt(data, key []byte) []byte {
+	block, _ := des.NewCipher(key)
+	blockSize := block.BlockSize()
+	data = pkcs7Padding(data, blockSize)
+	blockMode := cipher.NewCBCEncrypter(block, key[:blockSize])
+
+	encrypted := make([]byte, len(data))
+	blockMode.CryptBlocks(encrypted, data)
+	return encrypted
+}
+
+// DesCbcDecrypt decrypt data with key use DES CBC algorithm
+// len(key) should be 8
+func DesCbcDecrypt(encrypted, key []byte) []byte {
+	block, _ := des.NewCipher(key)
+	blockSize := block.BlockSize()
+	blockMode := cipher.NewCBCDecrypter(block, key[:blockSize])
+
+	decrypted := make([]byte, len(encrypted))
+	blockMode.CryptBlocks(decrypted, encrypted)
+	decrypted = pkcs7UnPadding(decrypted)
+	return decrypted
+}
+
+// DesCtrCrypt encrypt data with key use DES CTR algorithm
+// len(key) should be 8
+func DesCtrCrypt(data, key []byte) []byte {
+	block, _ := des.NewCipher(key)
+
+	iv := bytes.Repeat([]byte("1"), block.BlockSize())
+	stream := cipher.NewCTR(block, iv)
+
+	dst := make([]byte, len(data))
+	stream.XORKeyStream(dst, data)
+
+	return dst
+}
+
+// DesCfbEncrypt encrypt data with key use DES CFB algorithm
+// len(key) should be 8
+func DesCfbEncrypt(data, key []byte) []byte {
+	block, err := des.NewCipher(key)
+	if err != nil {
+		panic(err)
+	}
+
+	encrypted := make([]byte, des.BlockSize+len(data))
+	iv := encrypted[:des.BlockSize]
+	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+		panic(err)
+	}
+
+	stream := cipher.NewCFBEncrypter(block, iv)
+	stream.XORKeyStream(encrypted[des.BlockSize:], data)
+	return encrypted
+}
+
+// DesCfbDecrypt decrypt data with key use DES CFB algorithm
+// len(encrypted) should be great than 16, len(key) should be 8
+func DesCfbDecrypt(encrypted, key []byte) []byte {
+	block, _ := des.NewCipher(key)
+	if len(encrypted) < des.BlockSize {
+		panic("encrypted data is too short")
+	}
+	iv := encrypted[:des.BlockSize]
+	encrypted = encrypted[des.BlockSize:]
+
+	stream := cipher.NewCFBDecrypter(block, iv)
+	stream.XORKeyStream(encrypted, encrypted)
+	return encrypted
+}
+
+// DesOfbEncrypt encrypt data with key use DES OFB algorithm
+// len(key) should be 16, 24 or 32
+func DesOfbEncrypt(data, key []byte) []byte {
+	block, err := des.NewCipher(key)
+	if err != nil {
+		panic(err)
+	}
+	data = pkcs7Padding(data, des.BlockSize)
+	encrypted := make([]byte, des.BlockSize+len(data))
+	iv := encrypted[:des.BlockSize]
+	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
+		panic(err)
+	}
+
+	stream := cipher.NewOFB(block, iv)
+	stream.XORKeyStream(encrypted[des.BlockSize:], data)
+	return encrypted
+}
+
+// DesOfbDecrypt decrypt data with key use DES OFB algorithm
+// len(key) should be 8
+func DesOfbDecrypt(data, key []byte) []byte {
+	block, err := des.NewCipher(key)
+	if err != nil {
+		panic(err)
+	}
+
+	iv := data[:des.BlockSize]
+	data = data[des.BlockSize:]
+	if len(data)%des.BlockSize != 0 {
+		return nil
+	}
+
+	decrypted := make([]byte, len(data))
+	mode := cipher.NewOFB(block, iv)
+	mode.XORKeyStream(decrypted, data)
+
+	decrypted = pkcs7UnPadding(decrypted)
+	return decrypted
+
+}