用Python实现对称加密模式（ECB、CBC、CFB、OFB等）

from cryptography.fernet import Fernet
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.backends import default_backend

# 生成一个密钥
key = Fernet.generate_key()

# 要加密的消息
message = b"pidancode.com"

# 使用Fernet进行加密和解密（ECB模式）
fernet = Fernet(key)
encrypted_message = fernet.encrypt(message)
decrypted_message = fernet.decrypt(encrypted_message)

print("Encrypted message (ECB):", encrypted_message)
print("Decrypted message (ECB):", decrypted_message)

# 使用Cipher进行加密和解密（CBC模式）
backend = default_backend()
iv = b"1234567890123456"
cipher = Cipher(algorithms.AES(key), modes.CBC(iv), backend=backend)
encryptor = cipher.encryptor()
encrypted_message = encryptor.update(message) + encryptor.finalize()

decryptor = cipher.decryptor()
decrypted_message = decryptor.update(encrypted_message) + decryptor.finalize()

print("Encrypted message (CBC):", encrypted_message)
print("Decrypted message (CBC):", decrypted_message)

# 使用Cipher进行加密和解密（CFB模式）
backend = default_backend()
iv = b"1234567890123456"
cipher = Cipher(algorithms.AES(key), modes.CFB(iv), backend=backend)
encryptor = cipher.encryptor()
encrypted_message = encryptor.update(message) + encryptor.finalize()

decryptor = cipher.decryptor()
decrypted_message = decryptor.update(encrypted_message) + decryptor.finalize()

print("Encrypted message (CFB):", encrypted_message)
print("Decrypted message (CFB):", decrypted_message)

# 使用Cipher进行加密和解密（OFB模式）
backend = default_backend()
iv = b"1234567890123456"
cipher = Cipher(algorithms.AES(key), modes.OFB(iv), backend=backend)
encryptor = cipher.encryptor()
encrypted_message = encryptor.update(message) + encryptor.finalize()

decryptor = cipher.decryptor()
decrypted_message = decryptor.update(encrypted_message) + decryptor.finalize()

print("Encrypted message (OFB):", encrypted_message)
print("Decrypted message (OFB):", decrypted_message)