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Add support for encrypted mi4 bootloaders.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12863 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Barry Wardell 2007-03-20 20:45:25 +00:00
parent 22a673062f
commit 3de41f5250
1 changed files with 237 additions and 46 deletions
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283
bootloader/main-pp.c
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@ -31,6 +31,194 @@
#include "disk.h"
#include <string.h>
/* Locations and sizes in hidden partition on Sansa */
#define PPMI_SECTOR_OFFSET 1024
#define PPMI_SECTORS 1
#define MI4_HEADER_SECTORS 1
#define MI4_HEADER_SIZE 0x200
/* mi4 header structure */
struct mi4header_t {
unsigned char magic[4];
uint32_t version;
uint32_t length;
uint32_t crc32;
uint32_t enctype;
uint32_t mi4size;
uint32_t plaintext;
uint32_t dsa_key[10];
uint32_t pad[109];
unsigned char type[4];
unsigned char model[4];
};
/* PPMI header structure */
struct ppmi_header_t {
unsigned char magic[4];
uint32_t length;
uint32_t pad[126];
};
inline unsigned int le2int(unsigned char* buf)
{
int32_t res = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
return res;
}
inline void int2le(unsigned int val, unsigned char* addr)
{
addr[0] = val & 0xFF;
addr[1] = (val >> 8) & 0xff;
addr[2] = (val >> 16) & 0xff;
addr[3] = (val >> 24) & 0xff;
}
struct tea_key {
const char * name;
uint32_t key[4];
};
#define NUM_KEYS 11
struct tea_key tea_keytable[] = {
{ "default" , { 0x20d36cc0, 0x10e8c07d, 0xc0e7dcaa, 0x107eb080 } },
{ "sansa", { 0xe494e96e, 0x3ee32966, 0x6f48512b, 0xa93fbb42 } },
{ "sansa_gh", { 0xd7b10538, 0xc662945b, 0x1b3fce68, 0xf389c0e6 } },
{ "rhapsody", { 0x7aa9c8dc, 0xbed0a82a, 0x16204cc7, 0x5904ef38 } },
{ "p610", { 0x950e83dc, 0xec4907f9, 0x023734b9, 0x10cfb7c7 } },
{ "p640", { 0x220c5f23, 0xd04df68e, 0x431b5e25, 0x4dcc1fa1 } },
{ "virgin", { 0xe83c29a1, 0x04862973, 0xa9b3f0d4, 0x38be2a9c } },
{ "20gc_eng", { 0x0240772c, 0x6f3329b5, 0x3ec9a6c5, 0xb0c9e493 } },
{ "20gc_fre", { 0xbede8817, 0xb23bfe4f, 0x80aa682d, 0xd13f598c } },
{ "elio_p722", { 0x6af3b9f8, 0x777483f5, 0xae8181cc, 0xfa6d8a84 } },
{ "c200", { 0xbf2d06fa, 0xf0e23d59, 0x29738132, 0xe2d04ca7 } },
};
/*
tea_decrypt() from http://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm
"Following is an adaptation of the reference encryption and decryption
routines in C, released into the public domain by David Wheeler and
Roger Needham:"
*/
/* NOTE: The mi4 version of TEA uses a different initial value to sum compared
to the reference implementation and the main loop is 8 iterations, not
32.
*/
static void tea_decrypt(uint32_t* v0, uint32_t* v1, uint32_t* k) {
uint32_t sum=0xF1BBCDC8, i; /* set up */
uint32_t delta=0x9E3779B9; /* a key schedule constant */
uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3]; /* cache key */
for(i=0; i<8; i++) { /* basic cycle start */
*v1 -= ((*v0<<4) + k2) ^ (*v0 + sum) ^ ((*v0>>5) + k3);
*v0 -= ((*v1<<4) + k0) ^ (*v1 + sum) ^ ((*v1>>5) + k1);
sum -= delta; /* end cycle */
}
}
/* mi4 files are encrypted in 64-bit blocks (two little-endian 32-bit
integers) and the key is incremented after each block
*/
static void tea_decrypt_buf(unsigned char* src, unsigned char* dest, size_t n, uint32_t * key)
{
uint32_t v0, v1;
unsigned int i;
for (i = 0; i < (n / 8); i++) {
v0 = le2int(src);
v1 = le2int(src+4);
tea_decrypt(&v0, &v1, key);
int2le(v0, dest);
int2le(v1, dest+4);
src += 8;
dest += 8;
/* Now increment the key */
key[0]++;
if (key[0]==0) {
key[1]++;
if (key[1]==0) {
key[2]++;
if (key[2]==0) {
key[3]++;
}
}
}
}
}
static inline bool tea_test_key(unsigned char magic_enc[8], uint32_t * key, int unaligned)
{
unsigned char magic_dec[8];
tea_decrypt_buf(magic_enc, magic_dec, 8, key);
return (le2int(&magic_dec[4*unaligned]) == 0xaa55aa55);
}
static int tea_find_key(struct mi4header_t *mi4header, int fd)
{
int i, rc;
unsigned int j;
uint32_t key[4];
unsigned char magic_enc[8];
int key_found = -1;
unsigned int magic_location = mi4header->length-4;
int unaligned = 0;
if ( (magic_location % 8) != 0 )
{
unaligned = 1;
magic_location -= 4;
}
/* Load encrypted magic 0xaa55aa55 to check key */
lseek(fd, MI4_HEADER_SIZE + magic_location, SEEK_SET);
rc = read(fd, magic_enc, 8);
if(rc < 8 )
return EREAD_IMAGE_FAILED;
printf("Trying key:");
for (i=0; i < NUM_KEYS && (key_found<0) ; i++) {
key[0] = tea_keytable[i].key[0];
key[1] = tea_keytable[i].key[1];
key[2] = tea_keytable[i].key[2];
key[3] = tea_keytable[i].key[3];
/* Now increment the key */
for(j=0; j<((magic_location-mi4header->plaintext)/8); j++){
key[0]++;
if (key[0]==0) {
key[1]++;
if (key[1]==0) {
key[2]++;
if (key[2]==0) {
key[3]++;
}
}
}
}
if (tea_test_key(magic_enc,key,unaligned))
{
key_found = i;
printf("%s...found", tea_keytable[i].name);
} else {
printf("%s...failed", tea_keytable[i].name);
}
}
return key_found;
}
/*
* CRC32 implementation taken from:
*
@ -122,40 +310,13 @@ unsigned char *loadbuffer = (unsigned char *)DRAM_START;
/* Bootloader version */
char version[] = APPSVERSION;
/* Locations and sizes in hidden partition on Sansa */
#define PPMI_SECTOR_OFFSET 1024
#define PPMI_SECTORS 1
#define MI4_HEADER_SECTORS 1
#define MI4_HEADER_SIZE 0x200
/* mi4 header structure */
struct mi4header_t {
unsigned char magic[4];
uint32_t version;
uint32_t length;
uint32_t crc32;
uint32_t enctype;
uint32_t mi4size;
uint32_t plaintext;
uint32_t dsa_key[10];
uint32_t pad[109];
unsigned char type[4];
unsigned char model[4];
};
/* PPMI header structure */
struct ppmi_header_t {
unsigned char magic[4];
uint32_t length;
uint32_t pad[126];
};
/* Load mi4 format firmware image */
int load_mi4(unsigned char* buf, char* firmware, unsigned int buffer_size)
{
int fd;
struct mi4header_t mi4header;
int rc;
unsigned int i;
unsigned long sum;
char filename[MAX_PATH];
@ -171,10 +332,6 @@ int load_mi4(unsigned char* buf, char* firmware, unsigned int buffer_size)
read(fd, &mi4header, MI4_HEADER_SIZE);
/* We don't support encrypted mi4 files yet */
if( (mi4header.plaintext + MI4_HEADER_SIZE) != mi4header.mi4size)
return EINVALID_FORMAT;
/* MI4 file size */
printf("mi4 size: %x", mi4header.mi4size);
@ -190,20 +347,54 @@ int load_mi4(unsigned char* buf, char* firmware, unsigned int buffer_size)
/* Read binary type (RBOS, RBBL) */
printf("Binary type: %.4s", mi4header.type);
/* Load firmware */
lseek(fd, MI4_HEADER_SIZE, SEEK_SET);
rc = read(fd, buf, mi4header.mi4size-MI4_HEADER_SIZE);
if(rc < (int)mi4header.mi4size-MI4_HEADER_SIZE)
return EREAD_IMAGE_FAILED;
/* Check CRC32 to see if we have a valid file */
sum = chksum_crc32 (buf,mi4header.mi4size-MI4_HEADER_SIZE);
printf("Calculated CRC32: %x", sum);
if(sum != mi4header.crc32)
return EBAD_CHKSUM;
/* Decrypt or calculate CRC */
if( (mi4header.plaintext + 0x200) != mi4header.mi4size)
{
/* Load encrypted firmware */
int key_index = tea_find_key(&mi4header, fd);
unsigned char encrypted_block[8];
unsigned int blocks_to_decrypt;
if (key_index < 0)
return EINVALID_FORMAT;
/* Load plaintext part */
lseek(fd, MI4_HEADER_SIZE, SEEK_SET);
rc = read(fd, buf, mi4header.plaintext );
if(rc < (int)mi4header.plaintext )
return EREAD_IMAGE_FAILED;
buf += mi4header.plaintext;
/* Load encrypted part */
blocks_to_decrypt = (mi4header.mi4size-(mi4header.plaintext+MI4_HEADER_SIZE))/8;
for(i=0; i < blocks_to_decrypt; i++)
{
lseek(fd, MI4_HEADER_SIZE + mi4header.plaintext + i*8, SEEK_SET);
rc = read(fd, encrypted_block, 8);
if(rc < 8)
return EREAD_IMAGE_FAILED;
tea_decrypt_buf(encrypted_block, buf, 8, tea_keytable[key_index].key);
buf += 8;
}
printf("%s key used", tea_keytable[key_index].name);
} else {
/* Load plaintext firmware */
lseek(fd, MI4_HEADER_SIZE, SEEK_SET);
rc = read(fd, buf, mi4header.mi4size-MI4_HEADER_SIZE);
if(rc < (int)mi4header.mi4size-MI4_HEADER_SIZE)
return EREAD_IMAGE_FAILED;
/* Check CRC32 to see if we have a valid file */
sum = chksum_crc32 (buf, mi4header.mi4size - MI4_HEADER_SIZE);
printf("Calculated CRC32: %x", sum);
if(sum != mi4header.crc32)
return EBAD_CHKSUM;
}
return EOK;
}
@ -378,7 +569,7 @@ void* main(void)
return (void*)loadbuffer;
}
error(EBOOTFILE, rc);
error(0, 0);
} else {
printf("Loading Rockbox...");