One of the knocks against the Propeller is it has no code protection, unlike PICs and other microcontrollers with onboard EEPROMs. And although the protection may be less than perfect, I can understand many companies are not willing to have their IP in an easily accessible state.
IMHO the way to remedy the situation is to include a small amount of onboard OTP storage for an encryption key and integrate a decryption routine into the bootloader. But for that to work someone (i.e. me) needs to code up the crypto routines. So I've been learning all about AES and working out how to code the routines in Propeller Assembly.
I've coded up a first attempt at the encryption routine and it's surprisingly compact - less than 1K. I've done some cycle counting and it's over 14K cycles per 128 bit block! At 80MHz that works out to 88K per second, so that's not too bad as far as load time is concerned, adding less than a half a second for 32K. The biggest time sync is the combined ShiftRows + SubBytes routine which has to do a table lookup for each byte and reorder the bytes in the four 32 bit columns at just under 1K cycles for each round, and there are 10 rounds per block.
And although crypto sounds big and scary, it's actually not that complex. The toughest part is keeping the byte order straight when reading the spec! (Like the 4 bytes which make up the 32 bit column are shown as [a0 a1 a2 a3], where a0 is the LSB!) AES breaks down into four or so main subroutines (SubByte which does a table lookup, ShiftRows which mixes bytes between words, MixColumns which does a matrix multiply on each column, and a routine to do a polynomial multiply by 2). The parts which operate on the 32 bit columns are easy on the Propeller, but the byte operations are painful!
My next step is to wrap the code in something I can use to view the results then start going through the sample data and make sure everything works.