DES decryption in Ruby - ruby

Question

The following is my java code for DES decryption:
public static byte[] decrypt(final byte[] value, final String key) throws InvalidKeyException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, NoSuchPaddingException, UnsupportedEncodingException, InvalidKeySpecException, IllegalBlockSizeException, BadPaddingException {
final DESKeySpec objDesKeySpec = new DESKeySpec(key.getBytes("UTF-8"));
final SecretKeyFactory objKeyFactory = SecretKeyFactory.getInstance("DES");
final SecretKey objSecretKey = objKeyFactory.generateSecret(objDesKeySpec);
final byte[] rgbIV = key.getBytes();
final IvParameterSpec iv = new IvParameterSpec(rgbIV);
final Cipher objCipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
objCipher.init(2, objSecretKey, iv);
return objCipher.doFinal(value);
}
And I try to convert it to Ruby code as the following:
def decryption(key, decodeString)
ALG = 'des'
cipher = OpenSSL::Cipher::Cipher.new(ALG)
cipher.decrypt #choose descryption mode.
cipher.key = key
plain = cipher.update(decodeString )
plain << cipher.final
end
After executing the java and ruby code, I got the same size of bytes, but the contents of bytes are different. Where did I go wrong?

Answer 1

Thanks for your question!
To do this, use the OpenSSL::Cipher library. Here is a link with some sample code for AES: http://www.ruby-doc.org/stdlib-1.9.3/libdoc/openssl/rdoc/OpenSSL/Cipher.html#class-OpenSSL::Cipher-label-Encrypting+and+decrypting+some+data
To use DES, run this command to see if your Ruby installation supports DES.
puts OpenSSL::Cipher.ciphers

Answer 2

According to this article : http://43n141e.blogspot.tw/2008/08/des-encryption-java-to-openssl-to-ruby.html , I try the following two steps :
1. Calculate iv value in Java:
String key = "123456"
final byte[] rgbIV = key.getBytes();
final IvParameterSpec iv = new IvParameterSpec(rgbIV);
byte[] ivBytes = iv.getIV();
StringBuffer sbuf = new StringBuffer();
for (byte b : ivBytes) {
sbuf.append(String.format("%02x", (b & 0xFF)));
}
System.out.println("iv: " + sbuf);
2. Decrypt in Ruby :
def decode(encryptedString, key, iv)
decrypt = OpenSSL::Cipher::Cipher.new('des-cbc')
decrypt.decrypt
decrypt.key = key
decrypt.iv = iv.scan(/../).map{|b|b.hex}.pack('c*')
decrypt.update(encryptedString) + decrypt.final
end
and it works !