Crate openentropy_tests 

NIST SP 800-22 inspired randomness test battery.

Provides 31 statistical tests for evaluating the quality of random byte sequences. Each test returns a TestResult with a p-value (where applicable), a pass/fail determination, and a letter grade (A through F).

Structs

TestResult

Result of a single randomness test.

Functions

anderson_darling

Test 20: Anderson-Darling – A-squared statistic for uniform. Critical values: 1.933 (5%), 2.492 (2.5%), 3.857 (1%).

approximate_entropy

Test 7: Approximate entropy – compare m and m+1 bit pattern frequencies (m=3).

autocorrelation

Test 15: Autocorrelation – at lags 1-50. Count violations of 2/sqrt(n) threshold.

binary_matrix_rank

Test 24: Binary matrix rank – GF(2) Gaussian elimination on 32x32 binary matrices.

birthday_spacing

Test 28: Birthday spacing – spacing between repeated values, Poisson test.

bit_avalanche

Test 29: Bit avalanche – adjacent bytes should differ by ~4 bits (50%).

block_frequency

Test 2: Block frequency – frequency within 128-bit blocks. Chi-squared test.

byte_frequency

Test 3: Byte frequency – chi-squared on byte value distribution (256 bins).

calculate_quality_score

Calculate overall quality score (0-100) from test results.

compression_ratio

Test 13: Compression ratio – zlib compression ratio (random ~ 1.0+).

cross_correlation

Test 18: Cross-correlation – even vs odd byte independence. Pearson r.

cusum_test

Test 26: Cumulative sums (CUSUM) – detect drift/bias.

dft_spectral

Test 8: DFT spectral – detect periodic features via FFT.

kolmogorov_complexity

Test 14: Kolmogorov complexity – compression at levels 1 and 9, compute complexity and spread.

ks_test

Test 19: Kolmogorov-Smirnov test vs uniform distribution.

lag_n_correlation

Test 17: Lag-N correlation – correlation at lags [1, 2, 4, 8, 16, 32].

linear_complexity

Test 25: Linear complexity – Berlekamp-Massey LFSR complexity on 200-bit blocks.

longest_run_of_ones

Test 5: Longest run of ones – within 8-bit blocks, chi-squared against theoretical probs.

maurers_universal

Test 23: Maurer’s universal statistical test (L=6, Q=640).

mean_variance

Test 31: Mean and variance – mean (~127.5) and variance (~5461.25) of uniform bytes.

min_entropy

Test 11: Min-entropy (NIST SP 800-90B): -log2(p_max).

monobit_frequency

Test 1: Monobit frequency – proportion of 1s vs 0s should be ~50%.

monte_carlo_pi

Test 30: Monte Carlo pi – estimate pi using (x,y) pairs in unit circle.

non_overlapping_template

Test 22: Non-overlapping template – non-overlapping occurrences of (0,0,1,1).

overlapping_template

Test 21: Overlapping template – frequency of overlapping bit pattern (1,1,1,1).

permutation_entropy

Test 12: Permutation entropy – complexity of ordinal patterns (order=4).

random_excursions

Test 27: Random excursions – cycles in cumulative sum random walk.

run_all_tests

Run the complete 31-test battery on a byte slice.

runs_test

Test 4: Runs test – number of uninterrupted runs of 0s or 1s.

serial_correlation

Test 16: Serial correlation – adjacent value correlation. Z-test.

serial_test

Test 6: Serial test – frequency of overlapping m-bit patterns (m=4).

shannon_entropy

Test 10: Shannon entropy – bits per byte (max 8.0).

spectral_flatness

Test 9: Spectral flatness – geometric/arithmetic mean ratio of power spectrum.