题目

解题

import string
import binascii
def Crack_4B(crc_list):
    print('-------------Start Crack CRC 4B-------------')
    #crc_list = [0xc0a3a573, 0x3cb6ab1c, 0x85bb0ad4, 0xf4fde00b]#文件的CRC32值列表，注意顺序
    comment = ''
    chars = string.printable
    flag = 0 

    for crc_value in crc_list:
        for char1 in chars:
            for char2 in chars:
                for char3 in chars:
                    for char4 in chars:
                        res_char = char1 + char2 + char3 + char4#获取遍历的任意4Byte字符
                        char_crc = binascii.crc32(res_char.encode())#获取遍历字符的CRC32值
                        calc_crc = char_crc & 0xffffffff#将遍历的字符的CRC32值与0xffffffff进行与运算
                        if calc_crc == crc_value:#将获取字符的CRC32值与每个文件的CRC32值进行匹配
                            print('[+] {}: {}'.format(hex(crc_value),res_char))
                            comment += res_char
                            flag = 1
                            break
                    if flag == 1:
                        break
                if flag == 1:
                        break
            if flag == 1:
                        break
        flag = 0
              
    print('-----------CRC Crack Completed-----------')
    print('Result: {}'.format(comment))

crc_list = [0xce70d424,0xc3f17511,0xf90c8a70,0xf8ab2771,0xc0ce8ee6,0xb2a6cde9,0x8637fa85,0x62f8f1a9]
Crack_4B(crc_list)

 -------------Start Crack CRC 4B-------------
[+] 0xce70d424: pass
[+] 0xc3f17511: word
[+] 0xf90c8a70:  is 
[+] 0xf8ab2771: gZin
[+] 0xc0ce8ee6: flAt
[+] 0xb2a6cde9: e_Ba
[+] 0x8637fa85: sE64
-----------CRC Crack Completed-----------
Result: password is gZinflAte_BasE64

# 读取文件内容
with open('1.txt', 'r') as file:
    data = file.read()
 
# 替换逗号为换行符，并写入新文件
with open('1_new.txt', 'w') as file:
    file.write(data.replace(',', '\n'))

# 读取文件的名称和路径  
input_filename = '1_new.txt'  
# 写入文件的名称和路径  
output_filename = 'output.txt'  
  
# 尝试打开文件以读取数据  
try:  
    with open(input_filename, 'r', encoding='utf-8') as file:  
        # 初始化一个空字符串来保存结果  
        result = ''  
          
        # 逐行读取文件  
        for line in file:  
            # 去除行尾的换行符，并检查长度是否为8  
            if len(line.strip()) == 8:  
                # 添加到结果字符串中  
                result += line.strip()  
  
# 如果需要，可以在每行之间加入换行符或分隔符  
# result += '\n'  # 如果你想要每8个字符的数据为一行  
  
# 尝试打开文件以写入结果  
    with open(output_filename, 'w', encoding='utf-8') as outfile:  
        # 写入结果到文件  
        outfile.write(result)  
  
except FileNotFoundError:  
    print(f"Error: File {input_filename} not found.")  
except IOError as e:  
    print(f"I/O error({e.errno}): {e.strerror}")  
  
# 如果一切顺利，输出提示信息  
print(f"Data extracted and saved to {output_filename}")

DASCTF{6eada6e841c2ecb63bca0a6742889b08}