First commit

monobit_test.py

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+#!/usr/bin/env python3
+
+from math import erfc, sqrt
+
+
+def monobit_test(bitseq: str):
+    """
+    Frequency (Monobit) Test for a binary sequence. This tests count the number of '1' and '0' in a bit sequence and make a test statistics
+
+    This test is based on the NIST SP 800-22 document, that describe how to perform tests for PRNG algorithms:
+    https://nvlpubs.nist.gov/nistpubs/legacy/sp/nistspecialpublication800-22r1a.pdf
+
+    Returns:
+        p_value (float): larger p-values suggest consistency with randomness.
+    """
+
+    n = len(bitseq)
+    if n == 0:
+        raise ValueError("bitseq must not be empty")
+
+    if any(c not in "01" for c in bitseq):
+        raise ValueError("bitseq must contain only '0' and '1'")
+
+    # Count ones and zeros via +/-1 sum
+    s = sum(1 if c == "1" else -1 for c in bitseq)
+
+    # Compute the test statistic
+    sobs = abs(s) / sqrt(n)
+
+    # Compute p-value, based on the Complementary Error Function (erfc)
+    p_value = erfc(sobs / sqrt(2))
+    return p_value