功能检查Caesar密码Python？

def caesar_encrypt(plaintext, key):
    ciphertext = ""
    for char in plaintext:
        if char.isalpha():
            ascii_offset = ord('A') if char.isupper() else ord('a')
            shifted_char = chr((ord(char) - ascii_offset + key) % 26 + ascii_offset)
            ciphertext += shifted_char
        else:
            ciphertext += char
    return ciphertext

def caesar_decrypt(ciphertext, key):
    return caesar_encrypt(ciphertext, -key)

plaintext = "Hello, World!"
key = 3

encrypted_text = caesar_encrypt(plaintext, key)
print("Encrypted text:", encrypted_text)

decrypted_text = caesar_decrypt(encrypted_text, key)
print("Decrypted text:", decrypted_text)