'Reads a signature from a byte string encoding accordint to IEEE P1363,
which is used by Microsoft\'s BCryptSignHash() function.
:param data:
A byte string from BCryptSignHash()
:return:
A DSASignature object'

@classmethod
def from_p1363(cls, data):

    r = int_from_bytes(data[0:(len(data) // 2)])
    s = int_from_bytes(data[(len(data) // 2):])
    return cls({u'r': r, u's': s})
