数字信封模块代码，python实现

from gmssl import sm2, sm3, sm4, func


# 随机生成sm4密钥
def generate_sm4_key():
    return func.random_hex(16)  # SM4密钥长度为128位（16字节）


# 使用SM4加密明文
def sm4_encode(key, data):
    sm4Alg = sm4.CryptSM4()  # 实例化sm4
    sm4Alg.set_key(key.encode(), sm4.SM4_ENCRYPT)  # 设置密钥
    enRes = sm4Alg.crypt_ecb(data.encode())  # 开始加密,bytes类型，ecb模式
    enHexStr = enRes.hex()
    return enHexStr  # 返回十六进制值


# 使用sm3生成消息摘要
def sm3_message_digest(data):
    digest = sm3.sm3_hash(func.bytes_to_list(data.encode()))
    # print(digest)
    return digest


# 生成SM2密钥对
def generate_sm2_key():
    sm2_crypt = sm2.CryptSM2(private_key='', public_key='')
    private_key, public_key = sm2.CryptSM2.generate_keypair(sm2_crypt)
    return private_key, public_key


# 使用接受方sm2公钥对sm4密钥进行加密
def public_sm2_encrypt(data, public_key):
    sm2_crypt = sm2.CryptSM2(public_key=public_key, private_key='')
    enc_data = sm2_crypt.encr