Meanderings on the iPad, Firewire and Security
As many iPad owners know, the iPad can only sync via USB. Charging via USB is limited to a select few newer computers that support 10W power over USB. Unfortunately, most Macs and PCs only support 2.5W-7.5W power over USB. Therefore Apple provides a small 10W power adapter and a short USB to Apple 30-pin Dock Connector cable.
Old school iPod owners will remember the days when the iPod supported Firewire and how ridiculously fast data transfers were before Apple decide to standardize on USB. As it turns out, Firewire also supports more power than USB. The average of most devices is 10W-20W power. The theoretical limit is 60W. Sounds like a nice fit for the iPad, right?? So why did Apple dump Firewire?
I found myself revisiting the time of the 4th Generation iPod (now in it's 6th Generation it's called the iPod Classic). The iPod Gen4 was the last iPod to support Firewire for both data transfer AND charging. This was in early 2005. At the time I and many others believed that Apple abandoned Firewire to lower the cost of the iPod's internals and to converge separate iPod product lines for Mac and PC. I still believe Apple saved significant cost and increased distribution with this move -- but I think it's only part of the reason. Apple has a long history of providing the best technology to it's Mac users even if it costs a few extra bucks. They could have included Firewire on all devices instead of omitting it. So something doesn't add up.
I remember that in 2005, the iTunes Music Store was under way and business was booming. Apple was pleased, but it's recording industry partners were distraught over the rampant reverse engineering of iTunes DRM protected music files. So, while Apple was innovating on the product/service side, they were simultaneously (contractually obligated) to fighting the reverse engineering of both the Fairplay DRM system and the iPod<->iTunes communications protocol.
On this hunch and also based on the iPhone jailbreaking cat and mouse game, I decided to research security issues related to USB vs. Firewire. I came across a presentation that discusses the differences between Firewire and USB from a security standpoint (PDF). I believe that the presenter makes a compelling argument for using USB instead of Firewire for secure proprietary communications protocols.
According to the presenter, Firewire's performance is a result of it's DMA (direct memory access) requirement. On Mac OS X, this is mediated and managed in a secure way. On the Windows 5.x series (2000, XP, etc) it remains a problem. Thus, it seems, that Apple made a choice to protect the iTunes ecosystem by eliminating Firewire from the iPod. One can only imagine the wonderful possibilities of reverse engineering and hardware hacking had Firewire lived on and been included in the iPhone and iPad.
-ankush
