Re: Diffie algorithm in openssl: and Java

[azhar jodatti]

On Wed, Mar 20, 2013 at 5:12 PM, Matt Caswell <fr...@baggins.org> wrote:

> On 20 March 2013 11:25, azhar jodatti <azhar...@gmail.com> wrote:
> > byte[] bobPubKeyEnc = bobKpair.getPublic().getEncoded();
>
> This is providing an encoded form of the public key, whereas your code
> is expecting it as an integer. Use the following instead:
>
> DHPublicKey dhpubkey = (DHPublicKey)(bobKpair.getPublic());
> BigInteger bobPubKeyInt = dhpubkey.getY();
>

​Yes, Matt. This worked and it also generates same secret key at both the
end :) :) :)
Thanks a lot. You been a great help to me.
One more query :).

After generating secret key :
byte[] bobSharedSecret = bobKeyAgree.generateSecret();//this generates
secret key. Note : this key matches with C client secret key :)

I am doing below stuff in JAVA :
       SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
        DESKeySpec desSpec = new DESKeySpec(bobSharedSecret);
        this.secretKey = skf.generateSecret(desSpec);

What is the equivalent of this in C?

this.secretKey is an object of javax.crypto.SecretKey which I am using for
symmetric encryption like this
        byte[] utf8 = plaintext.getBytes("UTF8");
        Cipher c = Cipher.getInstance("DES");
        c.init(Cipher.ENCRYPT_MODE, this.secretKey);
        byte[] encryptedText =  c.doFinal(utf8);
        return new sun.misc.BASE64Encoder().encode(encryptedText);

and decryption like this
       Cipher c = Cipher.getInstance("DES");
        byte[] decryptBase64= new
sun.misc.BASE64Decoder().decodeBuffer(incryptedData);
        c.init(Cipher.DECRYPT_MODE, this.secretKey);
        byte plaintext[] = c.doFinal(decryptBase64);
        return new String(plaintext,"UTF-8");









​


>
> Matt
> ______________________________________________________________________
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>

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