1  # MIT License
  2  #
  3  # Copyright (c) 2017 Thomas Dixon
  4  #
  5  # Permission is hereby granted, free of charge, to any person obtaining a copy
  6  # of this software and associated documentation files (the "Software"), to deal
  7  # in the Software without restriction, including without limitation the rights
  8  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  9  # copies of the Software, and to permit persons to whom the Software is
 10  # furnished to do so, subject to the following conditions:
 11  #
 12  # The above copyright notice and this permission notice shall be included in all
 13  # copies or substantial portions of the Software.
 14  #
 15  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 18  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 19  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 20  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 21  # SOFTWARE.
 22  
 23  import copy
 24  import struct
 25  import sys
 26  
 27  
 28  def new(m=None):
 29      return sha256(m)
 30  
 31  class sha256(object):
 32      _k = (0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
 33            0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
 34            0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
 35            0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
 36            0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
 37            0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
 38            0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
 39            0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
 40            0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
 41            0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
 42            0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
 43            0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
 44            0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
 45            0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
 46            0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
 47            0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2)
 48      _h = (0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
 49            0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19)
 50      _output_size = 8
 51      
 52      blocksize = 1
 53      block_size = 64
 54      digest_size = 32
 55      
 56      def __init__(self, m=None):        
 57          self._buffer = b""
 58          self._counter = 0
 59          
 60          if m is not None:
 61              if type(m) is not bytes:
 62                  raise TypeError('%s() argument 1 must be bytes, not %s' % (self.__class__.__name__, type(m).__name__))
 63              self.update(m)
 64          
 65      def _rotr(self, x, y):
 66          return ((x >> y) | (x << (32-y))) & 0xFFFFFFFF
 67                      
 68      def _sha256_process(self, c):
 69          w = [0]*64
 70          w[0:16] = struct.unpack('!16L', c)
 71          
 72          for i in range(16, 64):
 73              s0 = self._rotr(w[i-15], 7) ^ self._rotr(w[i-15], 18) ^ (w[i-15] >> 3)
 74              s1 = self._rotr(w[i-2], 17) ^ self._rotr(w[i-2], 19) ^ (w[i-2] >> 10)
 75              w[i] = (w[i-16] + s0 + w[i-7] + s1) & 0xFFFFFFFF
 76          
 77          a,b,c,d,e,f,g,h = self._h
 78          
 79          for i in range(64):
 80              s0 = self._rotr(a, 2) ^ self._rotr(a, 13) ^ self._rotr(a, 22)
 81              maj = (a & b) ^ (a & c) ^ (b & c)
 82              t2 = s0 + maj
 83              s1 = self._rotr(e, 6) ^ self._rotr(e, 11) ^ self._rotr(e, 25)
 84              ch = (e & f) ^ ((~e) & g)
 85              t1 = h + s1 + ch + self._k[i] + w[i]
 86              
 87              h = g
 88              g = f
 89              f = e
 90              e = (d + t1) & 0xFFFFFFFF
 91              d = c
 92              c = b
 93              b = a
 94              a = (t1 + t2) & 0xFFFFFFFF
 95              
 96          self._h = [(x+y) & 0xFFFFFFFF for x,y in zip(self._h, [a,b,c,d,e,f,g,h])]
 97          
 98      def update(self, m):
 99          if not m:
100              return
101  
102          if type(m) is not bytes:
103              raise TypeError('%s() argument 1 must be bytes, not %s' % (sys._getframe().f_code.co_name, type(m).__name__))
104          
105          self._buffer += m
106          self._counter += len(m)
107          
108          while len(self._buffer) >= 64:
109              self._sha256_process(self._buffer[:64])
110              self._buffer = self._buffer[64:]
111              
112      def digest(self):
113          mdi = self._counter & 0x3F
114          length = struct.pack('!Q', self._counter<<3)
115          
116          if mdi < 56:
117              padlen = 55-mdi
118          else:
119              padlen = 119-mdi
120          
121          r = self.copy()
122          r.update(b'\x80'+(b'\x00'*padlen)+length)
123          return b''.join([struct.pack('!L', i) for i in r._h[:self._output_size]])
124          
125      def hexdigest(self):
126          return self.digest().encode('hex')
127          
128      def copy(self):
129          return copy.deepcopy(self)