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We should check the CRC32 whether it is encrypted or not.

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Do the encryption in-place so that it is faster. 
Add comment explaining why we need our own CRC32 implemenatation.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12864 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Barry Wardell 2007-03-20 22:02:26 +00:00
parent 3de41f5250
commit 9a9aebb99e
1 changed files with 29 additions and 36 deletions
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65
bootloader/main-pp.c
View file

@ -220,6 +220,9 @@ static int tea_find_key(struct mi4header_t *mi4header, int fd)
}
/*
* We can't use the CRC32 implementation in the firmware library as it uses a
* different polynomial. The polynomial needed is 0xEDB88320L
*
* CRC32 implementation taken from:
*
* efone - Distributed internet phone system.
@ -316,7 +319,6 @@ 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];
@ -347,52 +349,43 @@ int load_mi4(unsigned char* buf, char* firmware, unsigned int buffer_size)
/* Read binary type (RBOS, RBBL) */
printf("Binary type: %.4s", mi4header.type);
/* Decrypt or calculate CRC */
if( (mi4header.plaintext + 0x200) != mi4header.mi4size)
/* Load firmware file */
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;
if( (mi4header.plaintext + MI4_HEADER_SIZE) != 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;
/* Plaintext part is already loaded */
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;
}
/* Decrypt in-place */
tea_decrypt_buf(buf, buf,
mi4header.mi4size-(mi4header.plaintext+MI4_HEADER_SIZE),
tea_keytable[key_index].key);
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)
/* Check decryption was successfull */
if(le2int(&buf[mi4header.length-4]) != 0xaa55aa55)
{
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;