| /*************************************************************************** |
| * __________ __ ___. |
| * Open \______ \ ____ ____ | | _\_ |__ _______ ___ |
| * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / |
| * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < |
| * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ |
| * \/ \/ \/ \/ \/ |
| * $Id$ |
| * |
| * Copyright (C) 2016 Amaury Pouly |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version 2 |
| * of the License, or (at your option) any later version. |
| * |
| * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY |
| * KIND, either express or implied. |
| * |
| ****************************************************************************/ |
| #ifndef __UPG_H__ |
| #define __UPG_H__ |
| |
| #include "misc.h" |
| #include "fwp.h" |
| #include "mg.h" |
| |
| /** Firmware format |
| * |
| * The firmware starts with the MD5 hash of the entire file (except the MD5 hash |
| * itself of course). This is used to check that the file was not corrupted. |
| * The remaining of the file is encrypted (using DES) with the model key. The |
| * encrypted part starts with a header containing the model signature and the |
| * number of files. Since the header is encrypted, decrypting the header with |
| * the key and finding the right signature serves to authenticate the firmware. |
| * The header is followed by N entries (where N is the number of files) giving |
| * the offset, within the file, and size of each file. Note that the files in |
| * the firmware have no name. */ |
| |
| struct upg_md5_t |
| { |
| uint8_t md5[16]; |
| }__attribute__((packed)); |
| |
| struct upg_header_t |
| { |
| uint8_t sig[NWZ_SIG_SIZE]; |
| uint32_t nr_files; |
| uint32_t pad; // make sure structure size is a multiple of 8 |
| } __attribute__((packed)); |
| |
| struct upg_entry_t |
| { |
| uint32_t offset; |
| uint32_t size; |
| } __attribute__((packed)); |
| |
| /** KAS / Key / Signature |
| * |
| * Since this is all very confusing, we need some terminology and notations: |
| * - [X, Y, Z] is a sequence of bytes, for example: |
| * [8, 0x89, 42] |
| * is a sequence of three bytes. |
| * - "abcdef" is a string: it is a sequences of bytes where each byte happens to |
| * be the ASCII encoding of a letter. So for example: |
| * "abc" = [97, 98, 99] |
| * because 'a' has ASCII encoding 97 and so one |
| * - HexString(Seq) refers to the string where each byte of the original sequence |
| * is represented in hexadecimal by two ASCII characters. For example: |
| * HexString([8, 0x89, 42]) = "08892a" |
| * because 8 = 0x08 so it represented by "08" and 42 = 0x2a. Note that the length |
| * of HexString(Seq) is always exactly twice the length of Seq. |
| * - DES(Seq,Pass) is the result of encrypting Seq with Pass using the DES cipher. |
| * Seq must be a sequence of 8 bytes (known as a block) and Pass must be a |
| * sequence of 8 bytes. The result is also a 8-byte sequence. |
| * - ECB_DES([Block0, Block1, ..., BlockN], Pass) |
| * = [DES(Block0,Pass), DES(Block1,Pass), ..., DES(BlockN,Pass)] |
| * where Blocki is a block (8 byte). |
| * |
| * |
| * A firmware upgrade file is always encrypted using a Key. To authenticate it, |
| * the upgrade file (before encryption) contains a Sig(nature). The pair (Key,Sig) |
| * is refered to as KeySig and is specific to each series. For example all |
| * NWZ-E46x use the same KeySig but the NWZ-E46x and NWZ-A86x use different KeySig. |
| * In the details, a Key is a sequence of 8 bytes and a Sig is also a sequence |
| * of 8 bytes. A KeySig is a simply the concatenation of the Key followed by |
| * the Sig, so it is a sequence of 16 bytes. Probably in an attempt to obfuscate |
| * things a little further, Sony never provides the KeySig directly but instead |
| * encrypts it using DES in ECB mode using a hardcoded password and provides |
| * the hexadecimal string of the result, known as the KAS, which is thus a string |
| * of 32 ASCII characters. |
| * Note that since DES works on blocks of 8 bytes and ECB encrypts blocks |
| * independently, it is the same to encrypt the KeySig as once or encrypt the Key |
| * and Sig separately. |
| * |
| * To summarize: |
| * Key = [K0, K1, K2, ..., K7] (8 bytes) (model specific) |
| * Sig = [S0, S1, S2, ..., S7] (8 bytes) (model specific) |
| * KeySig = [Key, Sig] = [K0, ... K7, S0, ..., S7] (16 bytes) |
| * FwpPass = "ed295076" (8 bytes) (never changes) |
| * EncKeySig = ECB_DES(KeySig, FwpPass) = [DES(Key, FwpPass), DES(Sig, FwpPass)] |
| * KAS = HexString(EncKeySig) (32 characters) |
| * |
| * In theory, the Key and Sig can be any 8-byte sequence. In practice, they always |
| * are strings, probably to make it easier to write them down. In many cases, the |
| * Key and Sig are even the hexadecimal string of 4-byte sequences but it is |
| * unclear if this is the result of pure luck, confused engineers, lazyness on |
| * Sony's part or by design. The following code assumes that Key and Sig are |
| * strings (though it could easily be fixed to work with anything if this is |
| * really needed). |
| * |
| * |
| * Here is a real example, from the NWZ-E46x Series: |
| * Key = "6173819e" (note that this is a string and even a hex string in this case) |
| * Sig = "30b82e5c" |
| * KeySig = [Key, Sig] = "6173819e30b82e5c" |
| * FwpPass = "ed295076" (never changes) |
| * EncKeySig = ECB_DES(KeySig, FwpPass) |
| * = [0x8a, 0x01, 0xb6, ..., 0xc5] (16 bytes) |
| * KAS = HexString(EncKeySig) = "8a01b624bfbfde4a1662a1772220e3c5" |
| * |
| */ |
| |
| /* API */ |
| |
| struct nwz_model_t |
| { |
| const char *model; /* rockbox model codename */ |
| bool confirmed; |
| /* If the KAS is confirmed, it is the one extracted from the device. Otherwise, |
| * it is a KAS built from a key and sig brute-forced from an upgrade. In this |
| * case, the KAS might be different from the 'official' one although for all |
| * intent and purposes it should not make any difference. */ |
| char *kas; |
| }; |
| |
| /* list of models with keys and status. Sentinel NULL entry at the end */ |
| extern struct nwz_model_t g_model_list[]; |
| |
| /* An entry in the UPG file */ |
| struct upg_file_entry_t |
| { |
| void *data; |
| size_t size; |
| }; |
| |
| struct upg_file_t |
| { |
| int nr_files; |
| struct upg_file_entry_t *files; |
| }; |
| |
| /* decrypt a KAS into a key and signature, return <0 if the KAS contains a non-hex |
| * character */ |
| int decrypt_keysig(const char kas[NWZ_KAS_SIZE], char key[NWZ_KEY_SIZE], |
| char sig[NWZ_SIG_SIZE]); |
| /* encrypt a key and signature into a KAS */ |
| void encrypt_keysig(char kas[NWZ_KEY_SIZE], |
| const char key[NWZ_SIG_SIZE], const char sig[NWZ_KAS_SIZE]); |
| |
| /* Read a UPG file: return a structure on a success or NULL on error. |
| * Note that the memory buffer is modified to perform in-place decryption. */ |
| struct upg_file_t *upg_read_memory(void *file, size_t size, char key[NWZ_KEY_SIZE], |
| char sig[NWZ_SIG_SIZE], void *u, generic_printf_t printf); |
| /* Write a UPG file: return a buffer containing the whole image, or NULL on error. */ |
| void *upg_write_memory(struct upg_file_t *file, char key[NWZ_KEY_SIZE], |
| char sig[NWZ_SIG_SIZE], size_t *out_size, void *u, generic_printf_t printf); |
| /* create empty upg file */ |
| struct upg_file_t *upg_new(void); |
| /* append a file to a upg, data is NOT copied */ |
| void upg_append(struct upg_file_t *file, void *data, size_t size); |
| /* release upg file, will free file data pointers */ |
| void upg_free(struct upg_file_t *file); |
| |
| #endif /* __UPG_H__ */ |