2022年 11月 5日

CRC算法python简单实现

 
  1. import copy
  2. import zlib
  3.  
  4.  
  5. # https://github.com/Michaelangel007/crc32
  6. def crc8():
  7.     test_crc8 = 0x11   # 数据
  8.     poly_crc8 = 0x11d  # 多项式
  9.     for bit in range(8):
  10.         if (test_crc8 & 0x80) != 0:   # 判断首位是否为1
  11.             test_crc8 <<= 1           # 右移 
  12.             test_crc8 ^= poly_crc8    # 异或计算
  13.         else:
  14.             test_crc8 <<= 1           # 不等于1则直接移位
  15.     print(hex(test_crc8))
  16.  
  17.  
  18. crc8()
  19.  
  20. def crc32():
  21.     test_crc32 = 0x01
  22.     test_crc32 <<= 24
  23.     poly_crc32_1 = 0xedb88320
  24.     poly_crc32_2 = 0x104c11db7
  25.     for bit in range(8):
  26.         if (test_crc32 & 0x80000000) != 0:  # 判断首位是否为1
  27.             test_crc32 <<= 1                # 右移
  28.             test_crc32 ^= poly_crc32_1      # 异或计算
  29.         else:
  30.             test_crc32 <<= 1                # 不等于1则直接移位
  31.     print(hex(test_crc32))
  32.  
  33.  
  34. def crc32_table_normal():   # 彩虹表算法，查表算法
  35.     crc32_table_normal_list = []
  36.     poly_crc32_normal = 0x104c11db7
  37.     for byte in range(256):
  38.         operator = copy.copy(byte)
  39.         operator <<= 24
  40.         for bit in range(8):
  41.             if (operator & 0x80000000) != 0:
  42.                 operator <<= 1
  43.                 operator ^= poly_crc32_normal
  44.             else:
  45.                 operator <<= 1
  46.         crc32_table_normal_list.append(operator)
  47.     to_print = list(map(hex, crc32_table_normal_list))
  48.     print(to_print)
  49.  
  50.  
  51. def crc32_table_recip():
  52.     crc32_table_recip_list = []
  53.     poly_crc32_recip = 0x104c11db7
  54.     for byte in range(256):
  55.         operator = copy.copy(byte)
  56.         operator = int('{:08b}'.format(operator)[::-1], 2)   # 倒置
  57.         operator <<= 24
  58.         for bit in range(8):
  59.             if (operator & 0x80000000) != 0:
  60.                 operator <<= 1
  61.                 operator ^= poly_crc32_recip
  62.             else:
  63.                 operator <<= 1
  64.         operator = int('{:032b}'.format(operator)[::-1], 2)  # 倒置
  65.         crc32_table_recip_list.append(operator)
  66.     to_print = list(map(hex, crc32_table_recip_list))
  67.     print(to_print)
  68.  
  69. def crc32_recip(line):
  70.     var = 0xffffffff
  71.     for ch in line:
  72.         operator = ord(ch)
  73.         operator = (operator ^ var) & 0xff
  74.         var = crc32_table_recip[operator] ^ (var >> 8)
  75.     return var ^ 0xffffffff
  76.  
  77.  
  78. # print(hex(zlib.crc32('123456789'.encode('utf-8'))))
  79. # print(hex(crc32_recip('123456789')))
  80.  
  81.  
  82. def crc32_normal(line):
  83.     var = 0xffffffff
  84.     for ch in line:
  85.         operator = ord(ch)
  86.         operator = int('{:08b}'.format(operator)[::-1], 2)
  87.         var = crc32_table_normal[operator]^(var << 8)& 0xffffffff
  88.     var = int('{:032b}'.format(operator)[::-1], 2)
  89.     return var ^ 0xffffffff
  90.  
  91.  
  92. # print(hex(crc32_normal('123456789')))
  93.  
  94.  
  95. def crc32_table_polyrev():
  96.     crc32_table_polyrev_list = []
  97.     poly_rev = 0xedb88320
  98.     for byte in range(256):
  99.         operator = copy.copy(byte)
  100.         for bit in range(8):
  101.             if (operator & 0x1) != 0:
  102.                 operator >>= 1
  103.                 operator^=poly_rev
  104.             else:
  105.                 operator >>= 1
  106.         crc32_table_polyrev_list.append(operator)
  107.     to_print_polyrev = list(map(hex, crc32_table_polyrev_list))
  108.     print(to_print_polyrev)
  109.  
  110.  
  111.  
  112. # crc逆算法
  113. def crc8_reverse():
  114.     test_crc32_result = 0xd0
  115.     poly_crc32 = 0x11d
  116.     for bit in range(8):
  117.         if test_crc32_result & 1 == 1:
  118.             test_crc32_result ^= poly_crc32
  119.             test_crc32_result <<= 1
  120.             test_crc32_result |= 0x80
  121.             continue
  122.         else:
  123.             test_crc32_result <<= 1
  124.     print(hex(test_crc32_result & 0x08))
  125.  
  126.  
  127. crc32_reverse()