Before you call me a n00b for looking for the encryption key, stop and read.
I found a 1.0 firmware dump. I decided to analyze it to see what it contained, and what PRXs you need to run homebrew.
I found a few security certificates. (screenshot included, please check rar file) I opened one. I found:
Below it was a string of letters. (screenshot included, please check rar file) Is this Sony's key?Public Key: RSA (1024 bit)
Now that you have read it, you can flame me and call me a n00b.
I am not sure if this is true. That is why it is in SPECULATION.