In the world of computers interoperability is key. If I send you an e-mail from my machine I should hope that you’re e-mail client would be able to read it. This is why we have standards. Standards are a good thing. They allow people to focus on improving performance and driving down costs instead of splintering user base and polluting the world with… less than elegant designs. But what if relying on a single standard is not the correct way to do things either?
In cryptography a key length refers to the digital size of the ‘key’ used to unlock the encryption algorithm. Over time the length of these keys has increased from DES’ modest 64 bit (really 56 bit) key size all the way to the new AES specified key lengths of 128 and 256 bit keys. Each bit increase in in the algorithm doubles the potential number of keys available to use, thus usually making it harder for an adversary to guess the right key.