Pure-python SHA-2 implementation, including all FIPS 180-2 specified variants (SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256)

sha2.py

#!/usr/bin/env python

import struct

def rightrotate(i, n, wsize):
    return ((i << (wsize-n)) & (2**wsize-1)) | (i >> n)

class SHA2(object):
    """Abstract class for SHA-2 variants"""
    def __init__(self):
        raise NotImplementedError

    def _add_chunk(self, chunk):
        self.count += 1
        unpack_fmt = ">16I"
        if self.wsize == 64:
            unpack_fmt = ">16Q"
        w = list( struct.unpack(unpack_fmt, chunk) + (None,) * (self.rounds-16) )
        for i in xrange(16, self.rounds):
            s0 = self.__class__.sigma0(w[i-15])
            s1 = self.__class__.sigma1(w[i-2])
            w[i] = (w[i-16] + s0 + w[i-7] + s1) % 2**self.wsize
        a,b,c,d,e,f,g,h = self.h
        for i in xrange(self.rounds):
            S1 = self.__class__.bigsigma1(e)
            ch = (e & f) ^ (~e & g)
            temp1 = (h + S1 + ch + self.__class__.k[i] + w[i]) % 2**self.wsize
            S0 = self.__class__.bigsigma0(a)
            maj = (a & b) ^ (a & c) ^ (b & c)
            temp2 = (S0 + maj) % 2**self.wsize

            h = g
            g = f
            f = e
            e = (d + temp1) % 2**self.wsize
            d = c
            c = b
            b = a
            a = (temp1 + temp2) % 2**self.wsize

        self.h[0] = (self.h[0] + a) % 2**self.wsize
        self.h[1] = (self.h[1] + b) % 2**self.wsize
        self.h[2] = (self.h[2] + c) % 2**self.wsize
        self.h[3] = (self.h[3] + d) % 2**self.wsize
        self.h[4] = (self.h[4] + e) % 2**self.wsize
        self.h[5] = (self.h[5] + f) % 2**self.wsize
        self.h[6] = (self.h[6] + g) % 2**self.wsize
        self.h[7] = (self.h[7] + h) % 2**self.wsize

    def add(self, data):
        message = self.remainder + data
        r = len(message) % self.bsize
        if r != 0:
            self.remainder = message[-r:]
        else:
            self.remainder = ""
        for chunk in xrange(0, len(message)-r, self.bsize):
            self._add_chunk( message[chunk:chunk+self.bsize] )
        return self

    def pad(self, l):
        raise NotImplementedError

    def _finish(self):
        l = len(self.remainder) + self.bsize * self.count
        self.add( self.pad(l) )
        assert(self.remainder == "")
        h = tuple(x for x in self.h)
        self.__init__()
        return h

class SHA2b256(SHA2):
    """Abstract class for SHA-2 variants with 256-bit block size"""
    bsize = 64
    rounds = 64
    wsize = 32
    k = (
            0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
            0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
            0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
            0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
            0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
            0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
            0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
            0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
            )

    @staticmethod
    def sigma0(word):
        return rightrotate(word,7,32) ^ rightrotate(word,18,32) ^ (word >> 3)
    @staticmethod
    def sigma1(word):
        return rightrotate(word,17,32) ^ rightrotate(word,19,32) ^ (word >> 10)
    @staticmethod
    def bigsigma1(word):
        return rightrotate(word, 6,32) ^ rightrotate(word, 11,32) ^ rightrotate(word, 25,32)
    @staticmethod
    def bigsigma0(word):
        return rightrotate(word, 2,32) ^ rightrotate(word, 13,32) ^ rightrotate(word, 22,32)

    def pad(self,l):
        return "\x80" + "\x00" * ((55 - l) % self.bsize) + struct.pack(">Q", l*8)

class SHA256(SHA2b256):
    def __init__(self, data=""):
        self.h = [
                0x6a09e667,
                0xbb67ae85,
                0x3c6ef372,
                0xa54ff53a,
                0x510e527f,
                0x9b05688c,
                0x1f83d9ab,
                0x5be0cd19
                ]
        self.remainder = data
        self.count = 0
    def finish(self):
        h = self._finish()
        return struct.pack(">8I", *h)

class SHA224(SHA2b256):
    def __init__(self, data=""):
        self.h = [
                0xc1059ed8,
                0x367cd507,
                0x3070dd17,
                0xf70e5939,
                0xffc00b31,
                0x68581511,
                0x64f98fa7,
                0xbefa4fa4
                ]
        self.remainder = data
        self.count = 0
    def finish(self):
        h = self._finish()[:7]
        return struct.pack(">7I", *h)

class SHA2b512(SHA2):
    """Abstract class for SHA-2 variants with 512-bit block size"""
    bsize = 128
    rounds = 80
    wsize = 64
    k = (
            0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f, 0xe9b5dba58189dbbc,
            0x3956c25bf348b538, 0x59f111f1b605d019, 0x923f82a4af194f9b, 0xab1c5ed5da6d8118,
            0xd807aa98a3030242, 0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
            0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235, 0xc19bf174cf692694,
            0xe49b69c19ef14ad2, 0xefbe4786384f25e3, 0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65,
            0x2de92c6f592b0275, 0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
            0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f, 0xbf597fc7beef0ee4,
            0xc6e00bf33da88fc2, 0xd5a79147930aa725, 0x06ca6351e003826f, 0x142929670a0e6e70,
            0x27b70a8546d22ffc, 0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
            0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6, 0x92722c851482353b,
            0xa2bfe8a14cf10364, 0xa81a664bbc423001, 0xc24b8b70d0f89791, 0xc76c51a30654be30,
            0xd192e819d6ef5218, 0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
            0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99, 0x34b0bcb5e19b48a8,
            0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb, 0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3,
            0x748f82ee5defb2fc, 0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
            0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915, 0xc67178f2e372532b,
            0xca273eceea26619c, 0xd186b8c721c0c207, 0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178,
            0x06f067aa72176fba, 0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
            0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc, 0x431d67c49c100d4c,
            0x4cc5d4becb3e42b6, 0x597f299cfc657e2a, 0x5fcb6fab3ad6faec, 0x6c44198c4a475817,
            )

    @staticmethod
    def sigma0(word):
        return rightrotate(word,1,64) ^ rightrotate(word,8,64) ^ (word >> 7)
    @staticmethod
    def sigma1(word):
        return rightrotate(word,19,64) ^ rightrotate(word,61,64) ^ (word >> 6)
    @staticmethod
    def bigsigma0(word):
        return rightrotate(word,28,64) ^ rightrotate(word,34,64) ^ rightrotate(word,39,64)
    @staticmethod
    def bigsigma1(word):
        return rightrotate(word, 14,64) ^ rightrotate(word,18,64) ^ rightrotate(word,41,64)

    def pad(self,l):
        lb = l * 8
        return "\x80" + "\x00" * ((111 - l) % self.bsize) + struct.pack(">QQ", lb >> 64, lb & (2**64-1))

class SHA384(SHA2b512):
    def __init__(self, data=""):
        self.h = [
                0xcbbb9d5dc1059ed8,
                0x629a292a367cd507,
                0x9159015a3070dd17,
                0x152fecd8f70e5939,
                0x67332667ffc00b31,
                0x8eb44a8768581511,
                0xdb0c2e0d64f98fa7,
                0x47b5481dbefa4fa4
                ]
        self.remainder = data
        self.count = 0
    def finish(self):
        h = self._finish()[:6]
        return struct.pack(">6Q", *h)

class SHA512(SHA2b512):
    def __init__(self, data=""):
        self.h = [
                0x6a09e667f3bcc908,
                0xbb67ae8584caa73b,
                0x3c6ef372fe94f82b,
                0xa54ff53a5f1d36f1,
                0x510e527fade682d1,
                0x9b05688c2b3e6c1f,
                0x1f83d9abfb41bd6b,
                0x5be0cd19137e2179
                ]
        self.remainder = data
        self.count = 0
    def finish(self):
        h = self._finish()
        return struct.pack(">8Q", *h)

class SHA512t(SHA512):
    """Base class for truncated SHA512 variants"""
    def __init__(self, t=None, data=""):
        if t is None:
            if not hasattr(self, "t"):
                raise TypeError, "Missing required argument 't'"
        elif t == 384:
            raise ValueError, "Use SHA384 instead"
        else:
            self.t = t
        super(SHA512t, self).__init__()
        self.h = map(lambda x: x ^ 0xa5a5a5a5a5a5a5a5, self.h)
        iv = "SHA-512/{0}".format(self.t)
        self.add( iv + self.pad(len(iv)) )
        self.remainder = data
        self.count = 0
    def finish(self):
        h = super(SHA512t, self)._finish()
        out = struct.pack(">8Q", *h)
        return out[:self.t//8]

class SHA512_224(SHA512t):
    def __init__(self, data=""):
        super(SHA512_224, self).__init__(t=224, data=data)

class SHA512_256(SHA512t):
    def __init__(self, data=""):
        super(SHA512_256, self).__init__(t=256, data=data)

if __name__=="__main__":
    tests = (
            (SHA224, "", "d14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f"),
            (SHA256, "", "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"),
            (SHA384, "", "38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b"),
            (SHA512, "", "cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e"),
            (SHA512_224, "", "6ed0dd02806fa89e25de060c19d3ac86cabb87d6a0ddd05c333b84f4"),
            (SHA512_256, "", "c672b8d1ef56ed28ab87c3622c5114069bdd3ad7b8f9737498d0c01ecef0967a"),
            )
    for klass, v, h in tests:
        h1 = klass(v).finish().encode('hex')
        if h1 == h:
            print "{0!r} - pass".format(klass)
        else:
            print "{0!r} - fail - {1}".format(klass, h1)