Enc

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Revision as of 20:35, 9 July 2018 by Yifan Lu (talk | contribs)
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Offset Size Description
0x0 0x4 0x64B2C8E5 magic
0x4 0x4 Offset to data
0x8 0x4 Size of plaintext version string, 0 on 0.931, 0x10 on other
0xC 0x4 Unknown/Zero
0x10 0x4 Data size
0x14 0xC Unknown/Zero
0x20 0x20 sha256 hash of decrypted body
0x40 0x10 Version in ASCII, not present on 0.931
0x50 (0x40 on 0.931) 0x90 Zero
0xE0 (0xD0 on 0.931) Until Data Encrypted Header

Encrypted Header

At offset 0xE0 there is a 0x1E0 sized buffer that is speculated to be an encrypted header. For any given firmware version, secure_kernel.enc/second_loader.enc and secure_kernel.enp/second_loader.enp share the first 0xC0 bytes. For non-retail PUPs, each SLSK share the first 0xC0 bytes as observed in 0.931, 0.995, 1.000.41. Similarly in retail PUPs, each SLSK also share the first 0xC0 bytes as observed in 1.05 and 3.60. However, the bytes differ from retail and non-retail SLSK.

There is likely a 0xC0 sized "common" header that is shared by every firmware and by both secure_kernel and second_loader but different between retail and non-retail builds. Then there is likely a 0x20 byte section that is unique per SLSK (maybe contains version, size, load offset, etc). Then a 0x100 byte RSA-2048 signature of the header.

Signature

The last 0x340 bytes of each SLSK is not personalized. For both secure_kernel and second_loader, both the enc and enp variants share the last 0x340 bytes (although they differ from each other and across firmwares). This is likely the signature and might also contain certificates.