| 410 | } |
| 411 | |
| 412 | bool Random_SanityCheck() |
| 413 | { |
| 414 | uint64_t start = GetPerformanceCounter(); |
| 415 | |
| 416 | /* This does not measure the quality of randomness, but it does test that |
| 417 | * OSRandom() overwrites all 32 bytes of the output given a maximum |
| 418 | * number of tries. |
| 419 | */ |
| 420 | static const ssize_t MAX_TRIES = 1024; |
| 421 | uint8_t data[NUM_OS_RANDOM_BYTES]; |
| 422 | bool overwritten[NUM_OS_RANDOM_BYTES] = {}; /* Tracks which bytes have been overwritten at least once */ |
| 423 | int num_overwritten; |
| 424 | int tries = 0; |
| 425 | /* Loop until all bytes have been overwritten at least once, or max number tries reached */ |
| 426 | do { |
| 427 | memset(data, 0, NUM_OS_RANDOM_BYTES); |
| 428 | GetOSRand(data); |
| 429 | for (int x=0; x < NUM_OS_RANDOM_BYTES; ++x) { |
| 430 | overwritten[x] |= (data[x] != 0); |
| 431 | } |
| 432 | |
| 433 | num_overwritten = 0; |
| 434 | for (int x=0; x < NUM_OS_RANDOM_BYTES; ++x) { |
| 435 | if (overwritten[x]) { |
| 436 | num_overwritten += 1; |
| 437 | } |
| 438 | } |
| 439 | |
| 440 | tries += 1; |
| 441 | } while (num_overwritten < NUM_OS_RANDOM_BYTES && tries < MAX_TRIES); |
| 442 | if (num_overwritten != NUM_OS_RANDOM_BYTES) return false; /* If this failed, bailed out after too many tries */ |
| 443 | |
| 444 | // Check that GetPerformanceCounter increases at least during a GetOSRand() call + 1ms sleep. |
| 445 | std::this_thread::sleep_for(std::chrono::milliseconds(1)); |
| 446 | uint64_t stop = GetPerformanceCounter(); |
| 447 | if (stop == start) return false; |
| 448 | |
| 449 | // We called GetPerformanceCounter. Use it as entropy. |
| 450 | RAND_add((const unsigned char*)&start, sizeof(start), 1); |
| 451 | RAND_add((const unsigned char*)&stop, sizeof(stop), 1); |
| 452 | |
| 453 | return true; |
| 454 | } |
| 455 | |
| 456 | FastRandomContext::FastRandomContext(bool fDeterministic) : requires_seed(!fDeterministic), bytebuf_size(0), bitbuf_size(0) |
| 457 | { |