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Thread: How to set secret key

  1. #1
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    Default How to set secret key

    Hi all,

    Below is a des encryption/decryption algorithm i grab from online.

    Questions:
    1) How can i set my own secret key instead of auto set key
    SecretKey key = KeyGenerator.getInstance("DES").generateKey();

    2)How to i print the sboxes because my assignment require me to analysis sboxes ?

    import javax.crypto.Cipher;
    import javax.crypto.KeyGenerator;
    import javax.crypto.SecretKey;
     
    class DesEncrypter {
      Cipher ecipher;
     
      Cipher dcipher;
     
      DesEncrypter(SecretKey key) throws Exception {
        ecipher = Cipher.getInstance("DES");
        dcipher = Cipher.getInstance("DES");
        ecipher.init(Cipher.ENCRYPT_MODE, key);
        dcipher.init(Cipher.DECRYPT_MODE, key);
      }
     
      public String encrypt(String str) throws Exception {
        // Encode the string into bytes using utf-8
        byte[] utf8 = str.getBytes("UTF8");
     
        // Encrypt
        byte[] enc = ecipher.doFinal(utf8);
     
        // Encode bytes to base64 to get a string
        return new sun.misc.BASE64Encoder().encode(enc);
      }
     
      public String decrypt(String str) throws Exception {
        // Decode base64 to get bytes
        byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);
     
        byte[] utf8 = dcipher.doFinal(dec);
     
        // Decode using utf-8
        return new String(utf8, "UTF8");
      }
    }
     
    public class Main {
      public static void main(String[] argv) throws Exception {
        SecretKey key = KeyGenerator.getInstance("DES").generateKey();
        DesEncrypter encrypter = new DesEncrypter(key);
        String encrypted = encrypter.encrypt("Don't tell anybody!");
        String decrypted = encrypter.decrypt(encrypted);
      }
    }


  2. #2
    mmm.. coffee JavaPF's Avatar
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    Default Re: How to set secret key

    Hopefully this link will help you - Secret Key Cryptography Tutorial
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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  3. #3
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    Default Re: How to set secret key

    Quote Originally Posted by JavaPF View Post
    Hopefully this link will help you - Secret Key Cryptography Tutorial
    Thanks !! The link was useful. I found the answer i looking for @ the comment section.

    Regarding my second question about the sbox. It is possible to have access to the sboxes?