openssl_encrypt used Python random to select steganography positions from a password-derived seed. The repair replaces this selection with an HMAC-SHA256-based shuffle.

@@ -0,0 +261,18 @@+        return psnr+    +    @staticmethod+    def generate_pseudorandom_sequence(seed: int, length: int, max_value: int) -> List[int]:+        """Generate pseudorandom sequence for pixel/sample selection"""+        import random+        random.seed(seed)+        return random.sample(range(max_value), min(length, max_value))+    +    @staticmethod

+    def analyze_entropy(data: bytes) -> float:+        """Calculate Shannon entropy of data"""+        if not data:+            return 0.0+        +        # Count byte frequencies+        byte_counts = [0] * 256+        for byte in data:

@@ -92,0 +112,18 @@+        # Generate enough random bytes for all swap decisions+        # Each swap needs log2(n) bits, but we use 4 bytes per swap for simplicity+        counter = 0+        for i in range(n - 1, 0, -1):+            # Generate deterministic random index using HMAC-SHA256+            hmac_input = struct.pack(">I", counter)+            h = hmac.new(key, hmac_input, hashlib.sha256).digest()+            # Use first 4 bytes as uint32, modulo (i+1) for unbiased index+            rand_val = struct.unpack(">I", h[:4])[0]+            j = rand_val % (i + 1)

+            items[i], items[j] = items[j], items[i]+            counter += 1++    @staticmethod+    def crypto_seeded_shuffle_np(items: list, key: bytes) -> None:+        """+        Deterministic cryptographic shuffle for numpy-compatible code.+        Uses HMAC-SHA256 to generate seed material for numpy Generator.