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Line 22: − + + − Data compression method is still unknown. If you calculate entropy of the data, you will notice that it is definitely not encrypted. Probably it uses a modified version of propieritary Nintendo compression method described here: http://everything2.com/index.pl?node_id=1469892+ + + + + + + + + + + + + + + + + + + + + + + + + + +
no edit summary
$0000 - $003F: padding (00)
$0000 - $003F: padding (00)
$0040 - $013F: rsa encrypted sha-1 signature of rest of the file
$0040 - $013F: rsa encrypted sha-1 signature of rest of the file
$0140 - $....: compressed data
$0140 - $0143: header
$0144 - .....: compressed data
</pre>
</pre>
The compression is very simple:
# Read one byte
# For each bit of the byte, msb-to-lsb,
#* if 0, copy one byte to the output
#* if 1, read 16 bits msb first in v, copy n bytes at offset m from the end of the output, n=3+(v>>12), m=v & fff
Quick and very dirty C code:
i = 0x144;
j = 0;
while(i < size) {
int k;
int v = data[i++];
for(k=0; k<8; k++)
if(!(v & (1 << (7-k)))) {
result_data[j++] = data[i++];
} else {
int vv = (data[i] << 8) | data[i+1];
int nb = 3+(vv >> 12);
int off = (vv & 0xfff);
int l;
i+=2;
for(l=0; l<nb; l++) {
result_data[j] = result_data[j-off-1];
j++;
}
}
}
[[Category:Software]][[Category:Wii channel]]
[[Category:Software]][[Category:Wii channel]]