mirror of
https://github.com/luzhisheng/js_reverse.git
synced 2025-04-19 18:24:51 +08:00
87 lines
2.7 KiB
Python
87 lines
2.7 KiB
Python
import string
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import random
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# base 字符集
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base64_charset = string.ascii_uppercase + string.ascii_lowercase + string.digits + '+/'
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base64_charset_list = list(base64_charset)
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random.shuffle(base64_charset_list)
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base64_charset = ''.join(base64_charset_list)
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def encode(orgin_string):
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"""
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将bytes类型编码为base64
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:param origin_bytes:需要编码的bytes
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:return:base64字符串
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"""
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origin_bytes = orgin_string.encode()
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# 将每一位bytes转换为二进制字符串
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base64_bytes = [f"{str(bin(b)).replace('0b', ''):0>8}" for b in origin_bytes]
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resp = ''
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nums = len(base64_bytes) // 3
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remain = len(base64_bytes) % 3
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integral_part = base64_bytes[0:3 * nums]
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while integral_part:
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# 取三个字节，以每6比特，转换为4个整数
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tmp_unit = ''.join(integral_part[0:3])
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tmp_unit = [int(tmp_unit[x: x + 6], 2) for x in [0, 6, 12, 18]]
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# 取对应base64字符
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resp += ''.join([base64_charset[i] for i in tmp_unit])
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integral_part = integral_part[3:]
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if remain:
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# 补齐三个字节，每个字节补充 0000 0000
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remain_part = ''.join(base64_bytes[3 * nums:]) + (3 - remain) * '0' * 8
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# 取三个字节，以每6比特，转换为4个整数
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# 剩余1字节可构造2个base64字符，补充==；剩余2字节可构造3个base64字符，补充=
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tmp_unit = [int(remain_part[x: x + 6], 2) for x in [0, 6, 12, 18]][:remain + 1]
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resp += ''.join([base64_charset[i] for i in tmp_unit]) + (3 - remain) * '='
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return resp
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def decode(base64_str):
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"""
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解码base64字符串
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:param base64_str:base64字符串
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:return:解码后的bytearray；若入参不是合法base64字符串，返回空bytearray
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"""
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# 对每一个base64字符取下标索引，并转换为6为二进制字符串
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base64_bytes = [f"{str(bin(base64_charset.index(s))).replace('0b', ''):0>6}" for s in base64_str if
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s != '=']
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resp = bytearray()
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nums = len(base64_bytes) // 4
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remain = len(base64_bytes) % 4
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integral_part = base64_bytes[0:4 * nums]
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while integral_part:
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# 取4个6位base64字符，作为3个字节
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tmp_unit = ''.join(integral_part[0:4])
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tmp_unit = [int(tmp_unit[x: x + 8], 2) for x in [0, 8, 16]]
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for i in tmp_unit:
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resp.append(i)
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integral_part = integral_part[4:]
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if remain:
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remain_part = ''.join(base64_bytes[nums * 4:])
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tmp_unit = [int(remain_part[i * 8:(i + 1) * 8], 2) for i in range(remain - 1)]
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for i in tmp_unit:
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resp.append(i)
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return str(bytes(resp),encoding="utf-8")
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if __name__ == '__main__':
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a = encode("NightTeam")
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b = decode(a)
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print(a)
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print("=====")
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print(b)
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