Hacked downgrade attempt on 1.51. Interesting results

[therod]

My PSP: Jap 1.51

Got hold of the 1.5 installer. Tried to install on PSP, was told the PSP was already upto date (as expected)

I then hex edited and replaced every string of "1.50" to "1.53". The PSP gave me the fancy logo, launched the installer, memory stick light flashes lots, but then get the following error message: "The update cannot be started. The data is corrupt"

Now, is the PSP actually launching the binary and then stopping because of a crc check on the update? Or is the psp not even getting to launch the binary at all after checking the digital sig?

[Cap'n 1time]

My PSP: Jap 1.51

Got hold of the 1.5 installer. Tried to install on PSP, was told the PSP was already upto date (as expected)

I then hex edited and replaced every string of "1.50" to "1.53". The PSP gave me the fancy logo, launched the installer, memory stick light flashes lots, but then get the following error message: "The update cannot be started. The data is corrupt"

Now, is the PSP actually launching the binary and then stopping because of a crc check on the update? Or is the psp not even getting to launch the binary at all after checking the digital sig?

I would imagine a simple crc checksum. I believe that the digital signitures are all the basicly the same. I reccomend you take these findings to ps2dev.org and post in their forums.

[iwilleatyourheart]

okay wtf? i tried exactly the same thing... im a noob before 1.5 even had emu capabilities i tried hex editing a japanese update (long ago dont ask which)... and i got same corrupted data error... figures lmfao

anyway i had no idea wtf hex editing was but i put in 1.51 for every 1.5 thinking if it updated all i needed was to take the firmware 1.0 pbp pack it somehow then boot it as 1.51... i had no idea this was of any use to homebrew industry so i discarded

[AKB]

just wait and wait.