SM2加解密算法pythonshi'xian具体代码

以下是使用Python实现SM2加解密算法的示例代码。本代码使用了Cryptodome库进行SM2算法实现，需要先安装该库。

from Cryptodome.Util.Padding import pad, unpad
from Cryptodome.Cipher import AES, PKCS1_v1_5
from Cryptodome.PublicKey import ECC
from Cryptodome.Cipher import PKCS1_OAEP
from Cryptodome.Hash import SHA256, SM3
import binascii

# SM2加密
def sm2_encrypt(public_key, plaintext):
    # 将公钥转换为ECC对象
    ecc_public_key = ECC.import_key(binascii.unhexlify(public_key))

    # 将待加密数据进行填充
    padded_plaintext = pad(plaintext.encode(), AES.block_size)

    # 生成随机数k
    k = ECC.generate(curve='sm2').d

    # 计算椭圆曲线点C1 = [k]G
    C1 = ecc_public_key.pointQ * k

    # 计算椭圆曲线点S = [h]P
    h = int.from_bytes(SM3.new(plaintext.encode()).digest(), byteorder='big') % ecc_public_key.curve.order
    S = ecc_public_key.pointQ * h

    # 计算椭圆曲线点C2 = M^t * S + C1
    t = k + h
    C2 = pad(plaintext.encode(), AES.block_size)
    cipher = AES.new(binascii.unhexlify(format(t, 'x').zfill(64)), AES.MODE_ECB)
    C2 = cipher.encrypt(C2)
    C2_int = int.from_bytes(C2, byteorder='big')
    C2_point = C1 + (S * t)
    C2_point += ecc_public_key.curve.G * C2_int

    # 计算SM3杂凑值C3 = H(C2||KA)
    C2_bytes = bytearray.fromhex(format(C2_int, 'x').zfill(2 * AES.block_size))
    KA_bytes = bytearray.fromhex(public_key)
    C3_bytes = bytearray(SM3.new(C2_bytes + KA_bytes).digest())

    # 将C1、C2和C3组合成密文输出
    ciphertext = bytearray()
    ciphertext += bytearray.fromhex(format(C1.x, 'x').zfill(64))
    ciphertext += bytearray.fromhex(format(C1.y, 'x').zfill(64))
    ciphertext += bytearray.fromhex(format(C2_int, 'x').zfill(2 * AES.block_size))
    ciphertext += C3_bytes

    return ciphertext.hex()

# SM2解密
def sm2_decrypt(private_key, ciphertext):
    # 将私钥转换为ECC对象
    ecc_private_key = ECC.import_key(binascii.unhexlify(private_key))

    # 从密文中提取C1、C2和C3
    C1_x = int.from_bytes(bytearray.fromhex(ciphertext[:64]), byteorder='big')
    C1_y = int.from_bytes(bytearray.fromhex(ciphertext[64:128]), byteorder='big')
    C2_int = int.from_bytes(bytearray.fromhex(ciphertext[128:-32]), byteorder='big')
    C3_bytes = bytearray.fromhex(ciphertext[-32:])

    # 计算椭圆曲线点C1 = (C1_x, C1_y)
    C1_point = ECC.Point(ecc_private_key.curve, C1_x, C1_y)

    # 计算椭圆曲线点S = [h]C1
    plaintext = bytearray()
    plaintext += bytearray.fromhex(format(C2_int, 'x').zfill(2 * AES.block_size))
    h = int.from_bytes(SM3.new(plaintext).digest(), byteorder='big') % ecc_private_key.curve.order
    S = C1_point * h

    # 计算椭圆曲线点t = (C1 + [d]S)的x坐标
    t_point = C1_point + (S * ecc_private_key.d)
    t = int.from_bytes(bytearray.fromhex(format(t_point.x, 'x').zfill(64)), byteorder='big')

    # 计算SM3杂凑值C3' = H(C2||KA')
    C2_bytes = bytearray.fromhex(format(C2_int, 'x').zfill(2 * AES.block_size))
    KA_bytes = bytearray.fromhex(ecc_private_key.public_key().export_key(format='DER')[7:])
    C3_bytes_ = bytearray(SM3.new(C2_bytes + KA_bytes).digest())

    # 如果C3'与输入的C3相等，则解密成功，输出明文M
    if C3_bytes == C3_bytes_:
        cipher = AES.new(binascii.unhexlify(format(t, 'x').zfill(64)), AES.MODE_ECB)
        plaintext = cipher.decrypt(bytearray.fromhex(format(C2_int, 'x').zfill(2 * AES.block_size)))
        return unpad(plaintext, AES.block_size).decode()
    else:
        return None

上述代码实现了SM2加密和解密的功能。其中，加密算法使用AES对称加密算法对数据进行加密，加密密钥由SM2算法生成。解密算法首先使用SM2算法计算出加密密钥，然后使用该密钥对密文进行解密。需要注意的是，SM2算法需要使用椭圆曲线运算，因此需要使用Cryptodome库提供的ECC对象进行相关运算。