BIOS Update Curiosity

As someone who is in the unfortunate camp of the non-gifted when it comes to most things coded, I find myself curious about something and lack the ability to find out for myself through trial and error.

My current query is this: What prevents savvy coders from being able to fool a regular PSP into a version update to custom firmware?

Take, for example, the hack to run homebrew on the GameCube using Phantasy Star Online and a proxy program on a PC. Would it be possible to set up a similar deal to send a custom firmware to a PSP that's trying to do a Network Update? I assume the challenges for this method would be the same as those for simply placing a custom firmware EBOOT onto a memory stick and updating that way, but since I'm not aware of what THOSE hurdles are anyway....

Anyhow, I appreciate any education those in the know can provide. I personally lucked out in finding a used downgradable PSP, but I plan to get a PSP for my sweetheart in the future, and want to be sure I can downgrade THAT unit without having to search for LCS.

The only way to downgrade is to be able to find an exploit in the firmware which enables you to access the kernel and run user code.
Sony makes a big deal of trying not to let this happen
and blocks every exploit with the next firmware update

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Originally Posted by Tesseract

As someone who is in the unfortunate camp of the non-gifted when it comes to most things coded, I find myself curious about something and lack the ability to find out for myself through trial and error.

My current query is this: What prevents savvy coders from being able to fool a regular PSP into a version update to custom firmware?

Take, for example, the hack to run homebrew on the GameCube using Phantasy Star Online and a proxy program on a PC. Would it be possible to set up a similar deal to send a custom firmware to a PSP that's trying to do a Network Update? I assume the challenges for this method would be the same as those for simply placing a custom firmware EBOOT onto a memory stick and updating that way, but since I'm not aware of what THOSE hurdles are anyway....

Anyhow, I appreciate any education those in the know can provide. I personally lucked out in finding a used downgradable PSP, but I plan to get a PSP for my sweetheart in the future, and want to be sure I can downgrade THAT unit without having to search for LCS.

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It may be possible to fool the network update into downloading a firmware upgrade from a computer in one's own home, however, running it will be a different matter.

The problem with a custom firmware is that it requires homebrew to run. The official upgrades are encrypted with AES 128 encryption. Once the file is unpacked (to allow for editing of the DATA.PSAR file) the encryption is broken and thus will not be read by the PSP (will cause a Corrupt Data error).

The only possible way to make it function afterwards is to re-encrypt it with the keys that Sony holds.

However, there is an addition to custom firmware (either a plugin or as part 3.10 OE; not sure) that turns Network Update into a Custom Firmware updater in the event that a new version of the custom firmware is released.

But it cannot work as far as a non-homebrew PSP is concerned.

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Originally Posted by F9zDark

However, there is an addition to custom firmware (either a plugin or as part 3.10 OE; not sure) that turns Network Update into a Custom Firmware updater in the event that a new version of the custom firmware is released.

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Its a plugin

Thanks Dark, I think that was the answer I was looking for, in that it wasn't GETTING the file, but EXECUTING it that's the problem.

Has any work gone into analysing the encryption, or is that just too beefy of a job?

From what I have heard about it, it seems nearly impossible. Symmetric key encryption is very solid and AES 128 is what the government uses to encrypt their secret information. Apparently there is no theoretical flaw in the method, but people have reportedly been able to crack it monitoring the actual system that it is running on looking at power consumption, computation time and other such methods that someone would never do with a psp...