How to Mock Image Signing Cost in Python

import math
import struct


def sign_image_cost(image_signature: bytes) -> int:
    """Deterministic mock signing cost based on image signature bytes."""
    if not image_signature:
        raise ValueError("Empty image signature")
    digest = 0
    for byte in image_signature:
        digest = (digest * 31 + byte) & 0xFFFFFFFF
    # Costs depend on image size (first 4 bytes as little-endian) and complexity
    size = struct.unpack("<I", image_signature[:4])[0]
    complexity = digest % 100
    return 10 + size // 1024 + complexity


if __name__ == "__main__":
    # Simulating an image signature: [size_bytes_le][sha256_partial]
    size_bytes = struct.pack("<I", 2048)
    hash_part = bytes(range(32))
    sig = size_bytes + hash_part
    cost = sign_image_cost(sig)
    print(f"Mock signing cost for image: {cost} units")