Module conditioning 

Centralized entropy conditioning module.

ALL post-processing of raw entropy lives here — no conditioning code should exist in individual source implementations. Sources produce raw bytes; this module is the single, auditable gateway for any transformation.

Architecture

Source → Raw Bytes → Conditioning Layer (this module) → Output

Conditioning Modes

• Raw: No processing. XOR-combined bytes pass through unchanged. Preserves the actual hardware noise signal for research.
• VonNeumann: Debias only. Removes first-order bias without destroying the noise structure. Output is shorter than input (~25% yield).
• Sha256: Full SHA-256 conditioning with counter and timestamp mixing. Produces cryptographically strong output but destroys the raw signal.

Most QRNG APIs (ANU, Outshift/Cisco) apply DRBG post-processing that makes output indistinguishable from PRNG. The Raw mode here is what makes openentropy useful for researchers studying actual hardware noise.

Structs

MinEntropyReport

Min-entropy analysis report with individual estimator results.

QualityReport

Enums

ConditioningMode

Conditioning mode for entropy output.

Functions

collision_estimate

Collision estimator (NIST-inspired diagnostic).

compression_estimate

Compression estimator (NIST-inspired diagnostic).

condition

Apply the specified conditioning mode to raw entropy bytes.

grade_min_entropy

Grade a source based on its min-entropy (H∞) value.

markov_estimate

Markov estimator (NIST-inspired diagnostic).

mcv_estimate

Most Common Value (MCV) estimator (NIST-inspired 800-90B 6.3.1 style). Estimates min-entropy with upper bound on p_max using confidence interval. Returns (min_entropy_bits_per_sample, p_max_upper_bound).

min_entropy

Min-entropy estimate: H∞ = -log2(max probability). More conservative than Shannon — reflects worst-case guessing probability. Returns bits per sample (0.0 to 8.0 for byte-valued data).

min_entropy_estimate

Min-entropy estimate with diagnostic side metrics.

quick_autocorrelation_lag1

Quick lag-1 autocorrelation for a byte slice.

quick_min_entropy

Quick min-entropy estimate using only the MCV estimator (NIST SP 800-90B 6.3.1).

quick_quality

Quick quality assessment.

quick_shannon

Quick Shannon entropy in bits/byte for a byte slice.

sha256_condition

SHA-256 condition with explicit state, sample, counter, and extra data. Returns (new_state, 32-byte output).

sha256_condition_bytes

SHA-256 chained conditioning: stretches or compresses raw bytes to exactly n_output bytes using counter-mode hashing.

t_tuple_estimate

t-Tuple estimator (NIST-inspired diagnostic). Estimates entropy from most frequent t-length tuple. Returns estimated min-entropy bits per sample.

von_neumann_debias

Von Neumann debiasing: extract unbiased bits from a biased stream.

xor_fold

XOR-fold: reduce data by XORing the first half with the second half. If the input has an odd length, the trailing byte is XORed into the last output byte to avoid silently discarding entropy.