On Mon, 14 Jul 2008, Mr Thant wrote:

On 14 Jul, 18:42, Tom Anderson wrote:

That article isn't outrageously detailed or specific, but taking it
together with the generic article on smart cards, i'd say that Oyster is
basically just memory, with a chip for accessing it and doing some
encryption. I would imagine it doesn't have firmware, BICBW.

Where do you think the encryption algorithm and the communication
protocol are stored?

In a ROM. To my mind, it has to be modifiable to be firmware, which makes
code in a ROM not firmware. Although thinking about it, my mind is
probably wrong on this point.

Or it could be done with an ASIC that isn't a microprocessor. It doesn't
need to be any more than a memory controller with an encryption processor
glued on the side.

They're called "smart" because they have a microprocessor running
software that decodes commands and reads, encrypts and transmits the
requested data.

Microprocessor or ASIC?

tom

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