macOS终端运行Python ECB检测程序无输出问题排查

尝试运行一段Python代码，但在macOS终端中始终没有任何输出。代码需要实现两个方法：countRepetitions（接收密文参数，返回所有16字节块的总重复次数）和detectECBMode（接收密文输入，判断是否存在块重复，返回布尔值标识是否为ECB模式加密）。期望程序读取密文文件后，输出ECB加密的十六进制格式密文及其重复次数。以下是代码：

from Crypto.Cipher import AES
from collections import Counter

def countRepetitions(ciphertext):
    blocks = [ciphertext[i:i+16] for i in range(0, len(ciphertext), 16)]
    return sum(count-1 for count in Counter(blocks).values())

def detectECBMode(ciphertext):
    blocks = [ciphertext[i:i+16] for i in range(0, len(ciphertext), 16)]
    return len(blocks) != len(set(blocks))

# Open the file and read all the lines
with open('ciphertexts.txt', 'r') as f:
    ciphertexts = [line.strip() for line in f]

# Iterate over each ciphertext and check if it was encrypted using ECB mode
for ciphertext in ciphertexts:
    if detectECBMode(ciphertext):
        repetitions = countRepetitions(ciphertext)
        print(f"Ciphertext in ECB mode -{ciphertext}")
        print(f"Repetitions - {repetitions}")
        break  # Stop after finding the first ciphertext encrypted using ECB mode

运行后终端无输出，寻求问题原因及解决方法。

• 核心逻辑错误：块分割单位错误
  ECB模式的块是16字节，对应32个十六进制字符。当前代码直接把十六进制字符串按16字符分割，相当于把8字节当成一个块，完全不符合ECB块检测的逻辑，导致无法识别出重复块。
  解决：先将十六进制字符串解码为二进制字节串，再按16字节分割块。修改后，两个方法的参数应为二进制字节串，而非原始十六进制字符串。

• 文件读取异常

  • 确认ciphertexts.txt与代码在同一目录，或使用绝对路径打开文件；若文件为空，循环无执行逻辑，自然无输出。
  • 检查文件内容：每行必须是完整的合法十六进制字符串，无多余空格或无效字符。

• 未处理解码异常
  若文件中存在非法十六进制行，程序会直接崩溃但无明确提示。需添加异常捕获，跳过无效行并给出提示。

• 冗余导入
  代码中导入的AES未被使用，可删除该语句以简化代码。

修改后的完整代码 #

from collections import Counter

def countRepetitions(cipher_bytes):
    # 按16字节分割二进制密文
    blocks = [cipher_bytes[i:i+16] for i in range(0, len(cipher_bytes), 16)]
    return sum(count-1 for count in Counter(blocks).values())

def detectECBMode(cipher_bytes):
    blocks = [cipher_bytes[i:i+16] for i in range(0, len(cipher_bytes), 16)]
    return len(blocks) != len(set(blocks))

with open('ciphertexts.txt', 'r') as f:
    ciphertexts = [line.strip() for line in f]

for ciphertext in ciphertexts:
    try:
        cipher_bytes = bytes.fromhex(ciphertext)
        if detectECBMode(cipher_bytes):
            repetitions = countRepetitions(cipher_bytes)
            print(f"Ciphertext in ECB mode: {ciphertext}")
            print(f"Repetitions: {repetitions}")
            break
    except ValueError:
        print(f"Invalid hex string: {ciphertext}, skipping...")

内容的提问来源于stack exchange，提问作者seule