import base64  
from pydantic import BaseModel, ValidationError  
  
def find_base64_truncation(encoded_data):  
    # 将输入字符串划分为4字符的组  
    for i in range(0, len(encoded_data), 4):  
        chunk = encoded_data[i:i+4]  
        try:  
            # 尝试解码当前4字符组  
            res = base64.b64decode(chunk)  
            print(f"解码成功，截断点位于索引 {i}, 字符组为 '{chunk}', 解码结果为: {res.decode()}")  
        except Exception as e:  
            # 如果解码失败，打印出错误位置和可能的截断点  
            print(f"可能的截断点位于索引 {i}, 字符组为 '{chunk}', 错误信息: {e}")  
            break  # 假设你有一个 Base64 编码的字符串  
encoded_data = "gAAAAABmK1YeWb24sQcKaJVtnmeoexGo3-W8dJlNEFrLZzBhtpZPUglAkG-VNzMBnLiY14vRuOORZen24-I0wVytnbNa61LO0UY2bZqF4k6vugsPGCgPUT5vvvm7hYlG3FcGwTG1zNM6EMfGelC2vS-LTFjByMwQ8AB_YjLtkRFaJ4nHEgUexow="
find_base64_truncation(encoded_data=encoded_data)
# Base64 解码  
# decoded_data = base64.b64decode(encoded_data)  
# print(decoded_data)