PBEWithMD5AndDES.go

package PBEWithMD5AndDES

import (
	"fmt"
	"strings"
	"encoding/base64"
	"crypto/cipher"
	"crypto/des"
	"crypto/md5"
)

func getDerivedKey(password string, salt []byte, count int) ([]byte, []byte) {
	key := md5.Sum([]byte(password + string(salt)))
	for i := 0; i < count - 1; i++ {
		key = md5.Sum(key[:])
	}
	return key[:8], key[8:]
}

func Encrypt(password string, obtenationIterations int, plainText string, salt []byte) (string, error) {
	padNum := byte(8 - len(plainText) % 8)
	for i := byte(0); i < padNum; i++ {
		plainText += string(padNum)
	}

	dk, iv := getDerivedKey(password, salt, obtenationIterations)

	block,err := des.NewCipher(dk)

	if err != nil {
		return "", err
	}

	encrypter := cipher.NewCBCEncrypter(block, iv)
	encrypted := make([]byte, len(plainText))
	encrypter.CryptBlocks(encrypted, []byte(plainText))

	return base64.StdEncoding.EncodeToString(encrypted), nil
}

func Decrypt(password string, obtenationIterations int, cipherText string, salt []byte) (string, error) {
	msgBytes, err := base64.StdEncoding.DecodeString(cipherText)
	if err != nil {
		return "", err
	}

	dk, iv := getDerivedKey(password, salt, obtenationIterations)
	block,err := des.NewCipher(dk)

	if err != nil {
		return "", err
	}

	decrypter := cipher.NewCBCDecrypter(block, iv)
	decrypted := make([]byte, len(msgBytes))
	decrypter.CryptBlocks(decrypted, msgBytes)

	decryptedString := strings.TrimRight(string(decrypted), "\x01\x02\x03\x04\x05\x06\x07\x08")

	return decryptedString, nil
}

func main() {
	salt := []byte{0xFF, 0x2B, 0x38, 0x30, 0xF8, 0x61, 0xEF, 0x99}
	password := "my_secret_password"
	iterations := 222
	originalText := "mythings"

	res, err := Encrypt(password, iterations, originalText, salt)
	fmt.Println("encripted", res, err)
	res, err = Decrypt(password, iterations, res, salt)
	fmt.Println("decripted", res, err)
}