It is all about breaking the chain of trust. You need to trick your PS3 to run your code at a sufficient low level. Just as the glitch hack on the XBOX, you can then manipulate the signature comparison (which is a memcmp) to always return true. Decrypting code was never a problem, because you need the public keys to do that (which are in the firmware). It's the private keys that made Firmwares up to 3.55 so interesting. By obtaining the private keys (which were obtainable by the fail of sony) we can make packages that run on OFW.
Having 3.60 or 3.73 public keys won't help you, unless you have a CFW that will unsigned or mal-signed code. Obtaining the 3.60 public keys shouldn't be hard, since they are public.
What I am missing in all of these discussions about keys is the mention whether they are public or private keys. This is a big difference.