nice rc4

rc4.py

class RC4:
    def __init__(self, key):
        self._key, x, box, kl = key, 0, range(256), len(key)
        for i in xrange(256):
            x = (x + box[i] + ord(key[i % kl])) & 0xff
            box[i], box[x] = box[x], box[i]
            
        self._box = box
    
    def crypt(self, data):
        box, x, y, out = self._box[:], 0, 0, []
        a = out.append
        for char in data:
            x = (x + 1) & 0xff
            r = box[x]
            y = (y + r) & 0xff
            r, j = box[x], box[y] = box[y], r
            a(chr(ord(char) ^ box[(r + j) & 0xff]))
        
        return ''.join(out)
        
    __call__ = crypt
    
import unittest
class RC4UnitTest(unittest.TestCase):
    def setUp(self):
        self.crypto = RC4('thisIsMyKey')
        
    def test_crypto(self):
        self.assertEqual(self.crypto('foobar'), '\x07\x9ci\xd2\xc3i')
        self.assertEqual(self.crypto('thhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh'),
                         '\x15\x9bn\xd8\xcase\x0f7L\x8dFrjS\xb2:\x95o6\x8aN#\xed(\xa1\xe4\xcdQ.c\xad\x8b\x0e\xb6x>\xde\xc6\x14)W\x9f\xff\xe5S\xc4\xfapC\x9d\xa6\xed')
        
if __name__ == '__main__':
    unittest.main()