summaryrefslogtreecommitdiffstats
path: root/apps/plugins/crypt_firmware.c
blob: 6bfeeabe000d2342741da8d8e89973249759d170 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
/***************************************************************************
 *
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 *
 * $Id: $
 * 
 * Rockbox plugin copyright (C) 2009 Dave Chapman.
 * Based on encryption code (C) 2009 Michael Sparmann
 *
 * 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.
 *
 ****************************************************************************/

/* 

   This viewer plugin is for the encryption/decryption of iPod Nano
   (2nd generation) firmware images using the hardware AES crypto unit
   in such devices.

   Encrypted images are stored with the modelname "nn2x" and extension
   ".ipodx" Unencrypted images use "nn2g" and ".ipod".

   Heavily based on Payloads/CryptFirmware/main.c from iBugger.

   The (C) from that file is as follows:

    Copyright 2009 TheSeven

    This file is part of TheSeven's iBugger.

    TheSeven's iBugger 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.

    TheSeven's iBugger is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with TheSeven's iBugger.  If not, see <http://www.gnu.org/licenses/>.

*/

#include "plugin.h"

PLUGIN_HEADER

static void aes_encrypt(void* data, uint32_t size)
{
    uint32_t ptr, i;
    uint32_t go = 1;
    PWRCONEXT &= ~0x400;
    AESTYPE = 1;
    AESUNKREG0 = 1;
    AESUNKREG0 = 0;
    AESCONTROL = 1;
    AESKEYLEN = 9;
    AESOUTSIZE = size;
    AESAUXSIZE = 0x10;
    AESINSIZE = 0x10;
    AESSIZE3 = 0x10;
    for (ptr = 0; ptr < (size >> 2); ptr += 4)
    {
        AESOUTADDR = (uint32_t)data + (ptr << 2);
        AESINADDR = (uint32_t)data + (ptr << 2);
        AESAUXADDR = (uint32_t)data + (ptr << 2);
        if (ptr != 0)
            for (i = 0; i < 4; i++)
                ((uint32_t*)data)[ptr + i] ^= ((uint32_t*)data)[ptr + i - 4];
        AESSTATUS = 6;
        AESGO = go;
        go = 3;
        while ((AESSTATUS & 6) == 0);
    }
    AESCONTROL = 0;
    PWRCONEXT |= 0x400;
}

static void aes_decrypt(void* data, uint32_t size)
{
    uint32_t ptr, i;
    uint32_t go = 1;
    PWRCONEXT &= ~0x400;
    AESTYPE = 1;
    AESUNKREG0 = 1;
    AESUNKREG0 = 0;
    AESCONTROL = 1;
    AESKEYLEN = 8;
    AESOUTSIZE = size;
    AESAUXSIZE = 0x10;
    AESINSIZE = 0x10;
    AESSIZE3 = 0x10;
    for (ptr = (size >> 2) - 4; ; ptr -= 4)
    {
        AESOUTADDR = (uint32_t)data + (ptr << 2);
        AESINADDR = (uint32_t)data + (ptr << 2);
        AESAUXADDR = (uint32_t)data + (ptr << 2);
        AESSTATUS = 6;
        AESGO = go;
        go = 3;
        while ((AESSTATUS & 6) == 0);
        if (ptr == 0) break;
        for (i = 0; i < 4; i++)
            ((uint32_t*)data)[ptr + i] ^= ((uint32_t*)data)[ptr + i - 4];
    }
    AESCONTROL = 0;
    PWRCONEXT |= 0x400;
}

static void calc_hash(uint32_t* data, uint32_t size, uint32_t* result)
{
    uint32_t ptr, i;
    uint32_t ctrl = 2;

    PWRCONEXT &= ~0x4;

    for (ptr = 0; ptr < (size >> 2); ptr += 0x10)
    {
      for (i = 0; i < 0x10; i++) HASHDATAIN[i] = data[ptr + i];
      HASHCTRL = ctrl;
      ctrl = 0xA;
      while ((HASHCTRL & 1) != 0);
    }
    for (i = 0; i < 5; i ++) result[i] = HASHRESULT[i];

    PWRCONEXT |= 0x4;
}

static uint32_t get_uint32be(unsigned char* buf)
{
    return (uint32_t)((buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]);
}

static void put_uint32be(unsigned char* buf, uint32_t x)
{
    buf[0] = (x & 0xff000000) >> 24;
    buf[1] = (x & 0xff0000) >> 16;
    buf[2] = (x & 0xff00) >> 8;
    buf[3] = x & 0xff;
}

static uint32_t calc_checksum(uint32_t sum, unsigned char* buf, int len)
{
   int i;

   for (i = 0; i < len ; i++) {
      sum += buf[i];
   }

   return sum;
}

enum plugin_status plugin_start(const void* parameter)
{
    int fd;
    int length;
    int n;
    ssize_t buf_size;
    uint32_t* buf;
    int size;
    uint32_t sum;
    uint32_t hash[0x200];
    char outputfilename[MAX_PATH];

    fd = rb->open(parameter,O_RDONLY);

    if (fd < 0) {
        rb->splash(HZ*2, "Cannot open file");
        return PLUGIN_ERROR;
    }

    length = rb->filesize(fd);

    if (length < 12) {
        rb->splash(HZ*2, "File too small");
        return PLUGIN_ERROR;
    }

    if (length > buf_size) {
        rb->splash(HZ*2, "File too big");
        return PLUGIN_ERROR;
    }

    /* Get the audio buffer */
    buf = rb->plugin_get_audio_buffer((size_t *)&buf_size);

    /* Use uncached alias for buf - equivalent to buf |= 0x40000000 */
    buf += 0x10000000;

    n = rb->read(fd, buf, length);
    if (n < length) {
        rb->splash(HZ*2, "Cannot read file");
        return PLUGIN_ERROR;
    }
    rb->close(fd);

    size = length - 8;  /* Size of firmware image */

    if (calc_checksum(MODEL_NUMBER, (unsigned char*)(buf + 2), size) != 
        get_uint32be((unsigned char*)buf)) {
        rb->splash(HZ*2, "Bad checksum in input file");
        return PLUGIN_ERROR;
    }

    n = rb->strlen(parameter);
    if (memcmp(buf+1,"nn2g",4)==0) {
        /* Encrypting - Input file should be .ipod, output file is .ipodx */

        if ((n < 6) || (rb->strcmp(parameter+n-5,".ipod") != 0)) {
            rb->splash(HZ*2, "Input filename must be .ipod");
            return PLUGIN_ERROR;
        }

        if (n + 2 > MAX_PATH) {
            rb->splash(HZ*2, "Filename too long");
            return PLUGIN_ERROR;
        }

        size = (size + 0x3f) & ~0x3f;  /* Pad to multiple of 64 bytes */
        if (size > (length - 8)) {
            rb->memset(&buf[length/4], 0, size - (length - 8));
        }

        rb->strlcpy(outputfilename, parameter, MAX_PATH);
        outputfilename[n] = 'x';
        outputfilename[n+1] = 0;

        /* Everything is OK, now do the encryption */

        /* 1 - Calculate hashes */

        rb->memset(hash, 0, sizeof(hash));

        hash[1] = 2;
        hash[2] = 1;
        hash[3] = 0x40;
        hash[5] = size;

        calc_hash(buf + 2, size, &hash[7]);
        calc_hash(hash, 0x200, &hash[0x75]);

        /* 2 - Do the encryption */

        rb->splash(0, "Encrypting...");
        aes_encrypt(buf + 2, size);

        /* 3 - Update the Rockbox header */

        sum = calc_checksum(MODEL_NUMBER, (unsigned char*)hash, sizeof(hash));
        sum = calc_checksum(sum, (unsigned char*)(buf + 2), size); 
        put_uint32be((unsigned char*)buf, sum);
        memcpy(buf + 1, "nn2x", 4);

        /* 4 - Write to disk */
        fd = rb->open(outputfilename,O_WRONLY|O_CREAT|O_TRUNC);

        if (fd < 0) {
            rb->splash(HZ*2, "Could not open output file");
            return PLUGIN_ERROR;
        }

	n = rb->write(fd, buf, 8);
	n = rb->write(fd, hash, sizeof(hash));
	n = rb->write(fd, buf + 2, size);

        rb->close(fd);
    } else if (memcmp(buf + 1,"nn2x",4)==0) {
        /* Decrypting - Input file should be .ipodx, output file is .ipod */

        if ((n < 7) || (rb->strcmp(parameter+n-6,".ipodx") != 0)) {
            rb->splash(HZ*2, "Input filename must be .ipodx");
            return PLUGIN_ERROR;
        }

        rb->strlcpy(outputfilename, parameter, MAX_PATH);
        outputfilename[n-1] = 0;  /* Remove "x" at end of filename */

        /* Everything is OK, now do the decryption */

        size -= 0x800;  /* Remove hash size from firmware size */

        /* 1 - Decrypt */

        rb->splash(0, "Decrypting...");

        aes_decrypt(&buf[0x202], size);

        /* 2 - Calculate hashes to verify decryption */

        rb->lcd_clear_display();
        rb->splash(0, "Calculating hash...");

        rb->memset(hash, 0, sizeof(hash));

        hash[1] = 2;
        hash[2] = 1;
        hash[3] = 0x40;
        hash[5] = size;

        calc_hash(&buf[0x202], size, &hash[7]);
        calc_hash(hash, 0x200, &hash[0x75]);

        if ((memcmp(hash + 7, buf + 9, 20) != 0) ||
            (memcmp(hash + 75, buf + 77, 20) != 0)) {
            rb->splash(HZ*2, "Decryption failed - bad hash");
            return PLUGIN_ERROR;
        }

        /* 3 - Update the Rockbox header */

        sum = calc_checksum(MODEL_NUMBER, (unsigned char*)(&buf[0x202]), size); 
        put_uint32be((unsigned char*)buf, sum);
        memcpy(buf + 1, "nn2g", 4);

        /* 4 - Write to disk */
        fd = rb->open(outputfilename,O_WRONLY|O_CREAT|O_TRUNC);

        if (fd < 0) {
            rb->splash(HZ*2, "Could not open output file");
            return PLUGIN_ERROR;
        }

        n = rb->write(fd, buf, 8);
        n = rb->write(fd, &buf[0x202], size);

        rb->close(fd);
    } else {
        rb->splash(HZ*2,"Invalid input file");
        return PLUGIN_ERROR;
    }

    return PLUGIN_OK;
}