Fælles kryptering for .NET og java

AES er helt fint.

Man skal bare vælge præcis samme variant af AES i Java og .NET !

Eksempel følger.

package march;

import java.io.FileOutputStream;
import java.io.OutputStream;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class WriteAES {
    public static void main(String[] args) throws Exception {
        String key = "Top hemmelig key";
        byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
        String data = "Top hemmelige data";
        Cipher aes = Cipher.getInstance("AES/CBC/PKCS5Padding");
        aes.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key.getBytes("UTF-8"), "AES"), new IvParameterSpec(iv));
        byte[] cipher = aes.doFinal(data.getBytes("UTF-8"));
        OutputStream os = new FileOutputStream("C:\\aes.dat");
        os.write(cipher);
        os.close();
    }

}

package march;

import java.io.FileInputStream;
import java.io.InputStream;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class ReadAES {
    public static void main(String[] args) throws Exception {
        byte[] cipher = new byte[10000];
        InputStream is = new FileInputStream("C:\\aes.dat");
        int cipherlen = is.read(cipher);
        is.close();
        String key = "Top hemmelig key";
        byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
        String data = "Top hemmelige data";
        Cipher aes = Cipher.getInstance("AES/CBC/PKCS5Padding");
        aes.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key.getBytes("UTF-8"), "AES"), new IvParameterSpec(iv));
        String newdata = new String(aes.doFinal(cipher, 0, cipherlen), "UTF-8");
        if(!newdata.equals(data)) {
            System.out.println("Oops");
        }
    }
}

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace E
{
    public class Program
    {
        public static void Main(string[] args)
        {
            string key = "Top hemmelig key";
            byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
            string data = "Top hemmelige data";
            Rijndael aes = new RijndaelManaged();
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;
            ICryptoTransform encrypt = aes.CreateEncryptor(Encoding.UTF8.GetBytes(key), iv);
            byte[] cipher = encrypt.TransformFinalBlock(Encoding.UTF8.GetBytes(data), 0, Encoding.UTF8.GetByteCount(data));
            Stream stm = new FileStream(@"C:\aes.dat", FileMode.Create, FileAccess.Write);
            stm.Write(cipher, 0, cipher.Length);
            stm.Close();
        }
    }
}

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace E
{
    public class Program
    {
        public static void Main(string[] args)
        {
            byte[] cipher = new byte[10000];
            Stream stm = new FileStream(@"C:\aes.dat", FileMode.Open, FileAccess.Read);
            int cipherlen = stm.Read(cipher, 0, cipher.Length);
            stm.Close();
            string key = "Top hemmelig key";
            byte[] iv = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
            string data = "Top hemmelige data";
            Rijndael aes = new RijndaelManaged();
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;
            ICryptoTransform decrypt = aes.CreateDecryptor(Encoding.UTF8.GetBytes(key), iv);
            string newdata = Encoding.UTF8.GetString(decrypt.TransformFinalBlock(cipher, 0, cipherlen));
            if(newdata != data)
            {
                Console.WriteLine("Oops");
            }
        }
    }
}

Simpelthen suverænt, tak. Point?

yes

Hvorfor det hedder PKCS5 i Java og PKCS7 i .NET må du ikke spørge om, men det virker.

For optimal sikkerhedfor CBC bør iv være random ikke fast. Men iv må gerne være kendt bare den ikke er det samme fra gang til gang.