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/*
WiiExtensionLibrary (c) Circle of Current
http://code.google.com/p/circle-of-current/wiki/WiiExtensionLibrary
*/
#include "wiimote.h"
#include "wm_crypto.h"
#include "gpio2nesc.h"
// pointer to user function
static void (*wm_sample_event)();
// crypto data
static volatile unsigned char wm_rand[10];
static volatile unsigned char wm_key[6];
static volatile unsigned char wm_ft[8];
static volatile unsigned char wm_sb[8];
// virtual register
volatile unsigned char twi_reg[256];
volatile unsigned int twi_reg_addr;
static volatile unsigned char twi_first_addr_flag; // set address flag
static volatile unsigned char twi_rw_len; // length of most recent operation
void twi_slave_init(unsigned char addr)
{
// initialize stuff
twi_reg_addr = 0;
// set slave address
TWAR = addr << 1;
// enable twi module, acks, and twi interrupt
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA);
// enable interrupts
sei();
}
void twi_clear_int(unsigned char ack)
{
// get ready by clearing interrupt, with or without ack
if(ack != 0)
{
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
}
else
{
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
}
}
/*
I'd like to thank Hector Martin for posting his encryption method!
His website is http://www.marcansoft.com/
Decryption method found at http://www.derkeiler.com/pdf/Newsgroups/sci.crypt/2008-11/msg00110.pdf
*/
unsigned char wm_ror8(unsigned char a, unsigned char b)
{
// bit shift with roll-over
return (a >> b) | ((a << (8 - b)) & 0xFF);
}
void wm_gentabs()
{
unsigned char idx;
// check all idx
for(idx = 0; idx < 7; idx++)
{
// generate test key
unsigned char ans[6];
unsigned char tkey[6];
unsigned char t0[10];
unsigned char i;
for(i = 0; i < 6; i++)
{
ans[i] = pgm_read_byte(&(ans_tbl[idx][i]));
}
for(i = 0; i < 10; i++)
{
t0[i] = pgm_read_byte(&(sboxes[0][wm_rand[i]]));
}
tkey[0] = ((wm_ror8((ans[0] ^ t0[5]), (t0[2] % 8)) - t0[9]) ^ t0[4]);
tkey[1] = ((wm_ror8((ans[1] ^ t0[1]), (t0[0] % 8)) - t0[5]) ^ t0[7]);
tkey[2] = ((wm_ror8((ans[2] ^ t0[6]), (t0[8] % 8)) - t0[2]) ^ t0[0]);
tkey[3] = ((wm_ror8((ans[3] ^ t0[4]), (t0[7] % 8)) - t0[3]) ^ t0[2]);
tkey[4] = ((wm_ror8((ans[4] ^ t0[1]), (t0[6] % 8)) - t0[3]) ^ t0[4]);
tkey[5] = ((wm_ror8((ans[5] ^ t0[7]), (t0[8] % 8)) - t0[5]) ^ t0[9]);
// compare with actual key
if(memcmp(tkey, (void*)wm_key, 6) == 0) break; // if match, then use this idx
}
// generate encryption from idx key and rand
wm_ft[0] = pgm_read_byte(&(sboxes[idx + 1][wm_key[4]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[3]]));
wm_ft[1] = pgm_read_byte(&(sboxes[idx + 1][wm_key[2]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[5]]));
wm_ft[2] = pgm_read_byte(&(sboxes[idx + 1][wm_key[5]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[7]]));
wm_ft[3] = pgm_read_byte(&(sboxes[idx + 1][wm_key[0]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[2]]));
wm_ft[4] = pgm_read_byte(&(sboxes[idx + 1][wm_key[1]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[4]]));
wm_ft[5] = pgm_read_byte(&(sboxes[idx + 1][wm_key[3]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[9]]));
wm_ft[6] = pgm_read_byte(&(sboxes[idx + 1][wm_rand[0]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[6]]));
wm_ft[7] = pgm_read_byte(&(sboxes[idx + 1][wm_rand[1]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[8]]));
wm_sb[0] = pgm_read_byte(&(sboxes[idx + 1][wm_key[0]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[1]]));
wm_sb[1] = pgm_read_byte(&(sboxes[idx + 1][wm_key[5]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[4]]));
wm_sb[2] = pgm_read_byte(&(sboxes[idx + 1][wm_key[3]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[0]]));
wm_sb[3] = pgm_read_byte(&(sboxes[idx + 1][wm_key[2]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[9]]));
wm_sb[4] = pgm_read_byte(&(sboxes[idx + 1][wm_key[4]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[7]]));
wm_sb[5] = pgm_read_byte(&(sboxes[idx + 1][wm_key[1]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[8]]));
wm_sb[6] = pgm_read_byte(&(sboxes[idx + 1][wm_rand[3]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[5]]));
wm_sb[7] = pgm_read_byte(&(sboxes[idx + 1][wm_rand[2]])) ^ pgm_read_byte(&(sboxes[idx + 2][wm_rand[6]]));
}
void wm_slaveTxStart(unsigned char addr)
{
//twi_reg[0xfe] = 1;
if(addr >= 0x00 && addr < 0x08)
{
// call user event
wm_sample_event();
}
}
void wm_slaveRx(unsigned char addr, unsigned char l)
{
// if encryption data is sent, store them accordingly
unsigned int i;
if(addr >= 0x40 && addr < 0x46)
{
for(i = 0; i < 6; i++)
{
wm_rand[9 - i] = twi_reg[0x40 + i];
}
}
else if(addr >= 0x46 && addr < 0x4C)
{
for(i = 6; i < 10; i++)
{
wm_rand[9 - i] = twi_reg[0x40 + i];
}
for(i = 0; i < 2; i++)
{
wm_key[5 - i] = twi_reg[0x40 + 10 + i];
}
}
else if(addr >= 0x4C && addr < 0x50)
{
for(i = 2; i < 6; i++)
{
wm_key[5 - i] = twi_reg[0x40 + 10 + i];
}
if(addr + l == 0x50)
{
// generate decryption once all data is loaded
wm_gentabs();
}
}
}
void wm_newaction(unsigned char * d)
{
// load button data from user application
memcpy((void*)twi_reg, d, 8);
}
void wm_init(unsigned char * id, unsigned char * cal_data, void (*function)(void))
{
// link user function
wm_sample_event = function;
// start state
twi_reg[0xF0] = 0; // disable encryption
// set id
unsigned int i, j;
for(i = 0, j = 0xFA; i < 6; i++, j++)
{
twi_reg[j] = id[i];
}
// set calibration data
for(i = 0, j = 0x20; i < 6; i++, j++)
{
twi_reg[j] = cal_data[i];
}
#ifdef dev_detect_port
// initialize device detect pin
dev_detect_port &= 0xFF ^ _BV(dev_detect_pin);
dev_detect_ddr |= _BV(dev_detect_pin);
_delay_ms(500); // delay to simulate disconnect
// ready twi bus, no pull-ups
twi_port &= 0xFF ^ _BV(twi_scl_pin);
twi_port &= 0xFF ^ _BV(twi_sda_pin);
#endif
// start twi slave, link events
twi_slave_init(0x52);
#ifdef dev_detect_port
// make the wiimote think something is connected
dev_detect_port |= _BV(dev_detect_pin);
#endif
}
ISR(TWI_vect)
{
switch(TW_STATUS)
{
// Slave Rx
case TW_SR_SLA_ACK: // addressed, returned ack
case TW_SR_GCALL_ACK: // addressed generally, returned ack
case TW_SR_ARB_LOST_SLA_ACK: // lost arbitration, returned ack
case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration generally, returned ack
// get ready to receive pointer
twi_first_addr_flag = 0;
// ack
twi_clear_int(1);
break;
case TW_SR_DATA_ACK: // data received, returned ack
case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
if(twi_first_addr_flag != 0)
{
// put byte in register
unsigned char t = TWDR;
if(twi_reg[0xF0] == 0xAA && twi_reg_addr != 0xF0) // if encryption is on
{
// decrypt
twi_reg[twi_reg_addr] = (t ^ wm_sb[twi_reg_addr % 8]) + wm_ft[twi_reg_addr % 8];
}
else
{
twi_reg[twi_reg_addr] = t;
}
twi_reg_addr++;
twi_rw_len++;
}
else
{
// set address
twi_reg_addr = TWDR;
twi_first_addr_flag = 1;
twi_rw_len = 0;
}
twi_clear_int(1); // ack
break;
case TW_SR_STOP: // stop or repeated start condition received
// run user defined function
wm_slaveRx(twi_reg_addr - twi_rw_len, twi_rw_len);
twi_clear_int(1); // ack future responses
break;
case TW_SR_DATA_NACK: // data received, returned nack
case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
twi_clear_int(0); // nack back at master
break;
// Slave Tx
case TW_ST_SLA_ACK: // addressed, returned ack
case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
// run user defined function
wm_slaveTxStart(twi_reg_addr);
twi_rw_len = 0;
case TW_ST_DATA_ACK: // byte sent, ack returned
// ready output byte
if(twi_reg[0xF0] == 0xAA) // encryption is on
{
// encrypt
TWDR = (twi_reg[twi_reg_addr] - wm_ft[twi_reg_addr % 8]) ^ wm_sb[twi_reg_addr % 8];
}
else
{
TWDR = twi_reg[twi_reg_addr];
}
twi_reg_addr++;
twi_rw_len++;
twi_clear_int(1); // ack
break;
case TW_ST_DATA_NACK: // received nack, we are done
case TW_ST_LAST_DATA: // received ack, but we are done already!
// ack future responses
twi_clear_int(1);
break;
default:
twi_clear_int(0);
break;
}
}
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