nwztools: forgot file

Change-Id: I4341f2af71675cb795987ecc5ce12104445a9d97

utils/nwztools/upgtools/upg.h

@@ -0,0 +1,175 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   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__ */