Assistance with Public Key Cryptography

Question

I am trying to make my Server more secure, using public key cryptography. I'm not looking for examples on how this works, I understand it. I need help actually encrypting my strings that i'm sending...

So, currently, I'm simply making a public/private key string by taking the current nano time, and converting it into a hexidecimal string, 20 times.

It makes an output like:

8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df8ebe14df

which is fine.
But how would i encrypt my message, say "hi", with this key? I've tried converting both into binary, and multiplying them, but then i couldnt un-convert them, because to do that, there have to be spaces in the binary number, but to multiply them, there cant be. can anyone help me?

Thanks in advance!

Also, let me know if you need any more info!

Answer 1

Take a look at this example: http://stilius.net/java/java_ssl.php

Don't try to invent your own cryptographic algorithm, I know that it sounds interesting but it's also not very safe. Try to use already implemented algorithms and protocols. I suggest you to take a look at the link. Though if you do this just for the fun of it then go ahead, if it's for a client or for something that others (than you at least) use then stick to the known protocols.

Answer 2

It's not just an issue of formatting or playing with binary or hexadecimal numbers here. You don't make a public/private key the way you suggested, as it wouldn't have the necessary cryptographic properties that public/private keys usually have. Also, using the current time in nano s is hardly worthy of being used as any kind of an encryption key. If you want to do this in Java, there are libraries that can do public key crypto for you, such as BouncyCastle (http://bouncycastle.org/). It's quite easy to use and implement some amount of cryptographic security into your application with it.