Jack.Le
e43bf258e3
- Introduced .gitignore to exclude common Python artifacts and IDE files. - Added contour models for contour generation. - Implemented cryptographic utilities for data encryption and decryption. - Created CSV metadata model for handling wafer data. - Developed time-indexed data segment model. - Established local settings model for application configuration. - Added Z-wafer data models and parser for CSV file handling. - Implemented Marching Squares algorithm for contour generation.
91 lines
3.1 KiB
Python
91 lines
3.1 KiB
Python
import secrets
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from pathlib import Path
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from typing import Union
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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from cryptography.hazmat.backends import default_backend
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# ===== Crypto Utilities =====
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class CryptoHelper:
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"""Cryptographic utilities for wafer data encryption/decryption."""
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# ===== Hex/Byte Conversion =====
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@staticmethod
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def hex_string_to_bytearray(hex_str: str) -> bytes:
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"""Converts a hex string to bytes (e.g., '48656C6C6F' → b'Hello')."""
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if len(hex_str) % 2 != 0:
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raise ValueError("Hex string must have even length")
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try:
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return bytes.fromhex(hex_str)
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except ValueError as e:
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raise ValueError(f"Invalid hex string: {e}")
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@staticmethod
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def bytearray_to_hex_string(data: Union[bytes, bytearray]) -> str:
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"""Converts bytes to lowercase hex string."""
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return data.hex()
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# ===== Random Data =====
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@staticmethod
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def generate_random_bytes(length: int) -> bytes:
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"""Generates cryptographically secure random bytes."""
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if length < 0:
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raise ValueError("Length must be non-negative")
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return secrets.token_bytes(length)
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# ===== AES Decryption =====
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@staticmethod
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def decrypt_aes(data: bytes, key: bytes, iv: bytes) -> bytes:
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"""
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Decrypts AES-128-CBC data with PKCS7 padding.
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Args:
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data: Encrypted ciphertext (must be multiple of 16 bytes)
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key: 16-byte AES key
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iv: 16-byte IV
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Returns:
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Decrypted plaintext
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Raises:
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ValueError: If inputs are invalid
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cryptography.exceptions.InvalidSignature: On decryption failure
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"""
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if len(key) != 16:
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raise ValueError("Key must be 16 bytes (AES-128)")
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if len(iv) != 16:
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raise ValueError("IV must be 16 bytes")
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if len(data) == 0:
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return b""
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if len(data) % 16 != 0:
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raise ValueError("Ciphertext length must be multiple of 16 bytes")
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=default_backend())
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decrypt_ctx = cipher.decryptor()
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plaintext_padded = decrypt_ctx.update(data) + decrypt_ctx.finalize()
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# Remove PKCS7 padding
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pad_len = plaintext_padded[-1]
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if pad_len > 16 or pad_len == 0:
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raise ValueError("Invalid padding")
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return plaintext_padded[:-pad_len]
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# ===== Binary File I/O =====
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@staticmethod
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def save_to_binary_file(file_path: Union[str, Path], data: bytes) -> None:
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"""Writes bytes to a binary file."""
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Path(file_path).write_bytes(data)
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@staticmethod
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def read_from_binary_file(file_path: Union[str, Path]) -> bytes:
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"""Reads bytes from a binary file."""
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return Path(file_path).read_bytes()
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# ===== Convenience Helpers =====
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@classmethod
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def read_hex_string_from_binary_file(cls, file_path: Union[str, Path]) -> str:
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"""Reads binary file and returns hex string."""
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data = cls.read_from_binary_file(file_path)
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return cls.bytearray_to_hex_string(data)
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