In secured transactions over the Internet using PKI, there are symmetric and asymmetric encryptions. As I understand in PKI it is asymmetric (private and public key). Symmetric can be up to 256 bits and asymmetric up to 1024 bits. Can you explain which is which?
I'm going to point you to some cryptography and PKI references as this will help explain some of this to you. There are a variety of schemes used for secure transactions as well. First, key lengths can be of various sizes, and are implementation dependent. The key item (pardon the pun) is to remember that the longer the key, the greater the perceived security from it. It takes longer, and a greater amount of work to come up with all the possibilities for a particular key type. But you could be lucky, extremely lucky, and guess on the first try. Here's some references for you:
And two books:
"Applied Cryptography" by Bruce Schneier, John Wiley and Sons, 1996
"Cryptography Demystified" by John Hershey, McGraw-Hill 2003.