Java

public static byte[] encrypt (byte[] plainText , SecretKeySpec spc)<br />
	    throws NoSuchAlgorithmException,GeneralSecurityException  {<br />
	        Cipher cipher = Cipher.getInstance("AES");<br />
	        cipher.init(Cipher.ENCRYPT_MODE,spc);<br />
	        byte[] cipherText = cipher.doFinal( plainText);<br />
	        return cipherText ;<br />
	    }<br />
<br />
	    public static byte[] decrypt (byte[] cipherText , SecretKeySpec spec)<br />
	    throws NoSuchAlgorithmException,GeneralSecurityException {<br />
	        Cipher cipher = Cipher.getInstance("AES");<br />
	        cipher.init(Cipher.DECRYPT_MODE, spec);<br />
	        byte[] plainText = cipher.doFinal(cipherText);<br />
	        return plainText ;<br />
	    }<br />
<br />
	    public static void readfile(RandomAccessFile file, byte[] bytes) throws Exception<br />
	    {<br />
				file.seek(0);<br />
	            int offset = 0;<br />
	            int numRead = 0;<br />
	            while (offset < bytes.length<br />
	                   && (numRead=file.read(bytes, offset, bytes.length-offset)) >= 0) {<br />
	            offset += numRead;<br />
	            }<br />
	    }<br />
<br />
	    public static void main(String[] args) throws Exception {<br />
	try<br />
			{<br />
				// 1: open cipher file<br />
				RandomAccessFile cipherfile = new RandomAccessFile( "ciphertext2.dat", "r" );<br />
<br />
	            // read cipher text<br />
				byte[] bytes = new byte[(int)cipherfile.length()];<br />
	            readfile(cipherfile,bytes);<br />
<br />
	            // 3:<br />
	            RandomAccessFile file = new RandomAccessFile( "partial-key.dat", "r" );<br />
	            byte[] keybytes = new byte[(int)file.length()+4];<br />
	            readfile(file,keybytes);<br />
	            for(int i=0;i<256;i++)<br />
	            {<br />
	                keybytes[12]=(byte)i;<br />
	                for(int j=0;j<256;j++)<br />
	                {<br />
	                    keybytes[13]=(byte)j;<br />
	                    for(int k=0;k<265;k++)<br />
	                    {<br />
	                        keybytes[14]=(byte)k;<br />
	                        for(int l=0;l<265;l++)<br />
	                        {<br />
	                            keybytes[15]=(byte)l;<br />
	                            SecretKeySpec key = new SecretKeySpec(keybytes, "AES");<br />
	                            byte[] plain=new byte[(int)cipherfile.length()];<br />
	                            plain=decrypt (bytes,key);<br />
	                            for (int y=0;y<=plain.length;y++)<br />
	                                System.out.print((char)plain[y]);<br />
	                        }<br />
	                }<br />
	                }<br />
	            }<br />
<br />
	            file.close();<br />
<br />
	            // 5: close file<br />
				cipherfile.close();<br />
	        }<br />
			catch ( FileNotFoundException e)<br />
			{<br />
				System.out.println(e);<br />
			}<br />
			catch ( IOException e)<br />
			{<br />
				System.out.println(e);<br />
			}<br />
		}<br />