/* Fills BUF with SIZE pseudo-random bytes. */
void
prng_get_bytes (void *buf_, size_t size)
{
unsigned char *buf;
for (buf = buf_; size-- > 0; buf++)
*buf = prng_get_byte ();
}
/**
* Updates the locations of game objects after one timestep.
* Checks for collisions and updates state if we lost.
*/
void game_step() {
if (game_lost) return;
unsigned i;
if (timer_tick % 5 == 0) {
for (i = 0; i < NUM_PIPES; i++) {
if (pipes[i].position != -1) {
pipes[i].position--;
if (pipes[i].position == BIRD_POS - 1) score++;
}
}
pipespawn--;
if (pipespawn == 0) {
for (i = 0; i < NUM_PIPES; i++) {
if (pipes[i].position == -1) {
pipes[i].position = SCREEN_WIDTH - 1;
pipes[i].height = prng_get_byte() % (SKY_HEIGHT - PIPE_GAP);
break;
}
}
pipespawn = PIPE_TIME;
}
}
if (timer_tick % 7 == 0) {
if (bird_collide(bird_height)) {
game_lost = 1;
if (score > maxscore) maxscore = score;
return;
}
bird_height += bird_direction;
if (bird_countdown) {
bird_countdown--;
if (!bird_countdown) {
bird_direction = 1;
}
}
}
}
uint8_t rsa_encrypt_oaep(void* dest, uint16_t* out_length,
const void* src, uint16_t length_B,
rsa_publickey_t* key, const rsa_oaep_parameter_t *p,
const rsa_label_t* label, const void* seed){
if(!p){
p = &rsa_oaep_default_parameter;
}
if(!label){
label = &rsa_oaep_default_label;
}
uint16_t hv_len = (hfal_hash_getHashsize(p->hf)+7)/8;
if(length_B > bigint_length_B(&key->modulus) - 2*hv_len - 2){
/* message too long */
return 1;
}
uint16_t buffer_len = bigint_length_B(&key->modulus);
#if DEBUG
cli_putstr("\r\n buffer_len = ");
cli_hexdump_rev(&buffer_len, 2);
cli_putstr("\r\n modulus_len = ");
cli_hexdump_rev(&key->modulus.length_B, 2);
#endif
uint8_t* buffer = (uint8_t*)dest;
uint8_t off;
/* the following needs some explanation:
* off is the offset which is used for compensating the effect of
* changeendian() when it operates on multi-byte words.
* */
off = (sizeof(bigint_word_t) - (bigint_get_first_set_bit(&key->modulus)/8+1) % sizeof(bigint_word_t))
% (sizeof(bigint_word_t));
buffer += off;
buffer_len -= off;
uint8_t* seed_buffer = buffer + 1;
uint16_t db_len = buffer_len - hv_len - 1;
uint8_t* db = seed_buffer + hv_len;
uint16_t maskbuffer_len = db_len>hv_len?db_len:hv_len;
uint8_t maskbuffer[maskbuffer_len];
bigint_t x;
memset(dest, 0, seed_buffer - buffer + off);
memset(db + hv_len, 0, db_len - hv_len - length_B -1);
hfal_hash_mem(p->hf, db, label->label, label->length_b);
db[db_len - length_B - 1] = 0x01;
memcpy(db+db_len - length_B, src, length_B);
if(seed){
memcpy(seed_buffer, seed, hv_len);
}else{
/* generate random seed */
if(!prng_get_byte){
return 2; /* ERROR: no random generator specified */
}
uint16_t i;
for(i=0; i<hv_len; ++i){
seed_buffer[i] = prng_get_byte();
}
}
#if DEBUG
cli_putstr("\r\n msg (raw, pre-feistel):\r\n");
cli_hexdump_block(dest, bigint_length_B(&key->modulus), 4, 16);
#endif
p->mgf(maskbuffer, seed_buffer, hv_len, db_len, p->mgf_parameter);
memxor(db, maskbuffer, db_len);
p->mgf(maskbuffer, db, db_len, hv_len, p->mgf_parameter);
memxor(seed_buffer, maskbuffer, hv_len);
#if DEBUG
cli_putstr("\r\n msg (raw, post-feistel):\r\n");
cli_hexdump_block(dest, bigint_length_B(&key->modulus), 4, 16);
#endif
x.info = 0;
x.length_B = key->modulus.length_B;
x.wordv = dest;
bigint_adjust(&x);
rsa_os2ip(&x, NULL, bigint_length_B(&key->modulus));
#if DEBUG
cli_putstr("\r\ninput-msg (pre enc):\r\n");
cli_hexdump_rev(&src, 2);
cli_hexdump_block(src, length_B, 4, 16);
#endif
rsa_enc(&x, key);
#if DEBUG
cli_putstr("\r\ninput-msg (post enc):\r\n");
cli_hexdump_rev(&src, 2);
cli_hexdump_block(src, length_B, 4, 16);
#endif
rsa_i2osp(NULL, &x, out_length);
return 0;
}
