Encryption

examseeker

How much about encryption should I memorize and / or know? Do I need to study bit sizes and more? Is there an easy way to remember them all?

Thanks,
es

undomiel

PKI, symmetric/asymmetric, all the different algorithms, S/MIME and PGP implementations as well as authentication. Knowing the bit sizes is helpful as well but don't let it all overwhelm you, just take it a step at a time.

dynamik

You should memorize the popular types of encryption, whether they're symmetrical or asymmetrical, number of bits, and how they work (i.e. 3DES). It might be a little easier if you break them down into symmetric/asymmetric and learn them in groups, but it really comes down to just memorization.

supertechCETma

Know symmetrical from assymetrical. Know examples of each, who uses what. Know bit lengths. Know PKI.
repetition works for me.

examseeker

Thanks.. will do.. however, there are parts of asymmetric encryptions that I have questions about. I understand this kind of encryption--however, I do not completely understand how public and private keys work. I encrypt my message with my private key and the recipient decrypts it with my public key.. how do 2 keys work on the same message?

Thanks again

supertechCETma

http://www.certiguide.com/secplus/cg_sp_Chapter4BasicsofCryptographyDomain4015.htm

undomiel

It's the other way around actually. You use their public key to encrypt the message and they use their private key to decrypt it. Then when they send an encrypted message to you they use your public key to encrypt the message and you use your private key to decrypt. It uses a one-way method of encryption so that you can't decrypt with the same key. It encrypt to be specifically decrypted with a different key. So it isn't exactly that 2 keys work on the same message, it is more like 2 keys are working together to secure the message.

ThePistonDoctor

Good explanation undomiel. Example:

John wants to send an encrypted message to Sally. John encrypts the message with Sally's PUBLIC key (which everyone knows) and sends it off to Sally. Sally uses her private key to decrypt it. If John's message goes to Bill, Bill cannot decrypt it because his private key is not designed to work with Sally's public key. If the message, however, was encrypted with Bill's public key then Bill would be able to decrypt it and Sally wouldn't. If anyone wants to send a message to John, they must use John's public key to encrypt it or John will not be able to use his private key to decrypt it.

This is why it is so important to protect your PRIVATE key. If John's private key is compromised by an outside entity they would be able to read anything that was only supposed to be read by John. Even worse, they could potentially encrypt it again with John's public key and forward it on to him without him ever knowing the compromise took place.

dynamik

You should listen to this: http://twit.tv/sn34

It would actually be best if you started with #30 since that is when they begin talking about crypto.

This might help you too: http://en.wikipedia.org/wiki/Public-key_cryptography

examseeker

Great resource, dynamik! I will listen to all those podcasts!

Thanks again,