### Python 文件读写与加密解密示例 以下是基于提供的引用内容和专业知识编写的关于 Python 实现文件读写以及加密解密的示例代码。 #### 置换加密解密实现 置换加密是一种简单的加密方式，通过重新排列明文中的字符来达到加密的目的。下面是一个完整的置换加密解密过程： ```python def encrypt_plaintext(plaintext_file, ciphertext_file, key): with open(plaintext_file, "r") as f: text = f.read().split() encrypted_text = "" for i in key: try: char = str(text[int(i) - 1]) encrypted_text += char + ' ' except IndexError: pass encrypted_text = encrypted_text.strip() with open(ciphertext_file, "w") as f: f.write(encrypted_text[::-1]) # 倒序保存到文件中 return encrypted_text def decrypt_ciphertext(ciphertext_file, plaintext_file, key): with open(ciphertext_file, "r") as f: ciphered_text = f.read()[::-1].split() # 反转并分割字符串 decrypted_text = [] for idx in range(len(key)): position = int(key[idx]) - 1 if position < len(ciphered_text): decrypted_text.append(ciphered_text[position]) result = " ".join(decrypted_text) with open(plaintext_file, "w") as f: f.write(result) return result # 示例调用 encrypt_plaintext(r"C:\Users\hanhu\Desktop\加密解密\明文.txt", r"C:\Users\hanhu\Desktop\加密解密\密文.txt", ["3", "1", "2"]) decrypt_ciphertext(r"C:\Users\hanhu\Desktop\加密解密\密文.txt", r"C:\Users\hanhu\Desktop\加密解密\解密.txt", ["3", "1", "2"]) ``` 上述代码实现了基本的置换加密和解密功能[^1]。 --- #### 对称加密 (AES) 对于更安全的加密需求，可以使用 AES 对称加密算法。以下是对称加密的一个简单例子： ```python from Crypto.Cipher import AES import base64 def pad(s): block_size = AES.block_size padding_length = block_size - (len(s) % block_size) return s + bytes([padding_length] * padding_length) def unpad(s): return s[:-s[-1]] def aes_encrypt(plain_text, key): iv = b'0123456789abcdef' cipher = AES.new(pad(key.encode())[:16], AES.MODE_CBC, iv=iv) padded_plain_text = pad(plain_text.encode()) encrypted_bytes = cipher.encrypt(padded_plain_text) return base64.b64encode(iv + encrypted_bytes).decode('utf-8') def aes_decrypt(encoded_cipher_text, key): decoded_data = base64.b64decode(encoded_cipher_text) iv = decoded_data[:16] cipher = AES.new(pad(key.encode())[:16], AES.MODE_CBC, iv=iv) plain_text_padded = cipher.decrypt(decoded_data[16:]) return unpad(plain_text_padded).decode() # 示例调用 key = "mysecretpassword" text_to_encrypt = "This is a secret message." cipher_text = aes_encrypt(text_to_encrypt, key) print(f"Encrypted Text: {cipher_text}") decrypted_text = aes_decrypt(cipher_text, key) print(f"Decrypted Text: {decrypted_text}") ``` 此代码展示了如何使用 PyCryptodome 库进行 AES 加密和解密操作[^4]。 --- #### 非对称加密 (RSA) 如果需要更高的安全性，可以选择 RSA 非对称加密技术。下面是使用 `cryptography` 库实现 RSA 的示例： ```python from cryptography.hazmat.primitives.asymmetric import rsa, padding from cryptography.hazmat.primitives import hashes, serialization def generate_rsa_keys(): private_key = rsa.generate_private_key( public_exponent=65537, key_size=2048 ) public_key = private_key.public_key() return private_key, public_key def rsa_encrypt(public_key, message): encrypted_message = public_key.encrypt( message.encode(), padding.OAEP( mgf=padding.MGF1(algorithm=hashes.SHA256()), algorithm=hashes.SHA256(), label=None ) ) return encrypted_message def rsa_decrypt(private_key, encrypted_message): decrypted_message = private_key.decrypt( encrypted_message, padding.OAEP( mgf=padding.MGF1(algorithm=hashes.SHA256()), algorithm=hashes.SHA256(), label=None ) ).decode() return decrypted_message # 示例调用 private_key, public_key = generate_rsa_keys() message = "Secure Message!" encrypted_msg = rsa_encrypt(public_key, message) print(f"Encrypted Message: {base64.b64encode(encrypted_msg)}") decrypted_msg = rsa_decrypt(private_key, encrypted_msg) print(f"Decrypted Message: {decrypted_msg}") ``` 这段代码演示了如何生成 RSA 密钥对，并使用它们来进行加密和解密[^5]。 --- #### Excel 文件读写与加密 为了处理 Excel 文件的读写和加密，可以结合 Pandas 和其他库完成任务： ```python import pandas as pd from Crypto.Cipher import AES import base64 def read_excel(file_path): df = pd.read_excel(file_path) return df.to_csv(index=False) def write_encrypted_excel(input_file, output_file, key): data = read_excel(input_file) encrypted_data = aes_encrypt(data, key) with open(output_file, "wb") as f: f.write(base64.b64decode(encrypted_data)) # 示例调用 write_encrypted_excel("input.xlsx", "output.encrypted", "encryptionkey") ``` 以上代码片段说明了如何将 Excel 数据转换为 CSV 并对其执行加密存储[^2]。 ---