The SoC in each device have an AES coprocessor with the GID-key and UID-key built in.
Running The Engine
Currently, there are four ways to run the hardware AES engine:
- Use the AES payload released on OpenPwn.
- Patch iBoot to jump to aes_decrypt.
- Use OpenIBoot.
- Use the crypto bundle provided in XPwn to utilize it via userland. This method requires a kernel patch.
If you want to decrypt IMG3 files you need to use this. The GID-key currently has not been extracted from the phone, so the only way to use it is on the phone itself.
See Easier method of getting Img3 Key / IV for an iBoot patch.
Generated by encrypting 345A2D6C5050D058780DA431F0710E15 with the S5L8900 GID-key to get 188458A6D15034DFE386F23B61D43774
It is used as the encryption key for IMG2 files. With the introduction of IMG3 in 2.0, KBAGs are now used instead of the 0x837 key.
Dev Team wiki