from Crypto.Cipher import AES
import secrets
import time
import binascii  # 引入hexlify方法


class AES_CTR_DRBG:
    def __init__(self, personalization_string: bytes = b"", nonce: bytes = b""):
        self.keylen = 16  # AES密钥长度为128比特
        self.blocklen = 16  # AES块大小为128比特
        self.seedlen = 32  # 种子长度为256比特
        self.outlen = 16  # 输出长度为128比特

        # 重播种计数器，表明自初始化或者重播种期间获得新的熵输入依赖，请求随机数生成的次数
        self.reseed_counter = 0
        # 重播种计数器阈值，在重播种之前能够产生随机数的最大请求次数
        # level 1 2^20次
        # level 2 2^10次
        self.reseed_interval_in_counter = 1 << 30
        # 重播种时间阈值，距离上一次重播种的最大时间间隔，单位 秒
        # level 1 600s
        # level 2 60s
        self.reseed_interval_in_time = 6000
        # 最小的熵输入长度
        self.min_entropy_input_length = 32  # 256比特
        # 最大的熵输入长度
        self.max_ectropy_input_length = 1 << 35 - 1  # 2^35比特

        self.seed_material = b""
        self.aes = AES.new(b"\x00" * self.keylen, AES.MODE_ECB)
        self.AES_CTR_DRBG_Instantiate(personalization_string, nonce)

    def AES_CTR_DRBG_Instantiate(
        self, personalization_string: bytes = b"", nonce: bytes = b""
    )-> None:
        self.min_entropy = self.seedlen
        self.entropy_input = secrets.token_bytes(self.min_entropy)
        self.seed_material = self.entropy_input + nonce + personalization_string
        self.seed_material = self.AES_CTR_DRBG_df(self.seed_material, self.seedlen)
        self.Key = self.seed_material[: self.keylen]
        self.V = self.seed_material[-self.blocklen :]
        self.reseed_counter = 1
        self.last_reseed_time = int(time.time())

    def AES_CTR_DRBG_Update(self, seed_material:bytes, Key:bytes, V: bytes)->None:
        temp = b""
        while len(temp) < len(seed_material):
            V_int = (int.from_bytes(self.V, "big") + 1) % (1 << (8 * self.blocklen))
            self.V = V_int.to_bytes(self.blocklen, "big")
            temp += self.aes.encrypt(self.V)
        temp = temp[: len(seed_material)]
        temp = int.from_bytes(temp, "big") ^ int.from_bytes(seed_material, "big")
        temp = temp.to_bytes(len(seed_material), "big")
        self.Key = temp[: self.keylen]
        self.V = temp[-self.blocklen :]

    def AES_CTR_DRBG_df(self, input_string: bytes, number_of_bits_to_return: int):
        L = len(input_string).to_bytes(4, "big")
        N = number_of_bits_to_return.to_bytes(4, "big")
        S = L + N + input_string + b"\x80"
        while len(S) % self.blocklen != 0:
            S += b"\x00"
        temp = b""
        i = 0
        K = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F"[
            : self.keylen
        ]
        while len(temp) < self.keylen + self.outlen:
            IV = i.to_bytes(4, "big") + b"\x00" * (self.blocklen - 4)
            temp += self.CBC_MAC(K, IV + S)
            i += 1
        K = temp[: self.keylen]
        X = temp[self.keylen : self.keylen + self.outlen]
        tmp = b""
        while len(tmp) < number_of_bits_to_return:
            X = self.aes.encrypt(X)
            tmp += X
        requested_bits = tmp[:number_of_bits_to_return]
        return requested_bits

    def CBC_MAC(self, Key: bytes, data_to_MAC:bytes)->bytes:
        chaining_value = b"\x00" * self.blocklen
        for i in range(0, len(data_to_MAC), self.blocklen):
            block = data_to_MAC[i : i + self.blocklen]
            input_block = int.from_bytes(chaining_value, "big") ^ int.from_bytes(
                block, "big"
            )
            chaining_value = self.aes.encrypt(
                input_block.to_bytes(self.blocklen, "big")
            )
        return chaining_value

    def AES_CTR_DRBG_Reseed(self, additional_input: bytes)-> None:
        self.min_entropy = self.seedlen
        self.entropy_input = secrets.token_bytes(self.min_entropy)
        self.seed_material = self.entropy_input + additional_input
        self.seed_material = self.AES_CTR_DRBG_df(self.seed_material, self.seedlen)
        self.AES_CTR_DRBG_Update(self.seed_material, self.Key, self.V)
        self.reseed_counter = 1
        self.last_reseed_time = int(time.time())

    def AES_CTR_DRBG_Generate(
        self, requested_number_of_bits: int, additional_input: bytes = b""
    )-> bytes:
        length = requested_number_of_bits // 8
        returned_bits = b""
        if (
            self.reseed_counter > (1 << 48)
            or int(time.time()) - self.last_reseed_time > 600
        ):
            self.AES_CTR_DRBG_Reseed(additional_input)
        if additional_input != b"":
            additional_input = self.AES_CTR_DRBG_df(additional_input, self.seedlen)
            self.AES_CTR_DRBG_Update(additional_input, self.Key, self.V)
        else:
            additional_input = b"\x00" * self.seedlen
        while len(returned_bits) < length:
            V_int = (int.from_bytes(self.V, "big") + 1) % (1 << (8 * self.blocklen))
            self.V = V_int.to_bytes(self.blocklen, "big")
            output_block = self.aes.encrypt(self.V)
            returned_bits += output_block
        self.AES_CTR_DRBG_Update(additional_input, self.Key, self.V)
        self.reseed_counter += 1
        return returned_bits[:length]


if __name__ == "__main__":
    bit_len = int(input("Enter the length of the bit string to be generated(bit):"))
    num = int(input("Enter the number of the bit string to be generated:"))
    file_name = input("Enter the name of the saved file:")
    start_time = time.time()  # 记录开始时间
    aesDrbg = AES_CTR_DRBG()
    with open(file_name, "w") as f:  # 改为以文本方式写入
        for i in range(num):
            hex_output = binascii.hexlify(
                aesDrbg.AES_CTR_DRBG_Generate(bit_len)
            ).decode()  # 转为十六进制并解码为string
            f.write(hex_output + "\n")  # 在每次写入后换行

    end_time = time.time()  # 记录结束时间
    elapsed_time = end_time - start_time  # 计算经过的时间
    print(f"running time: {elapsed_time} ")  # 打印出运行时间