'Unwraps an RSA public key into an RSAPublicKey object. Does not support
DSA or EC public keys since they do not have an unwrapped form.
:return:
An RSAPublicKey object'

def unwrap(self):

    if (self.algorithm == u'rsa'):
        return self[u'public_key'].parsed
    key_type = self.algorithm.upper()
    a_an = (u'an' if (key_type == u'EC') else u'a')
    raise ValueError(unwrap(u'\n                                                Only    RSA    public    keys    may    be    unwrapped    -    this    key    is    %s    %s    public\n                                                key\n                                                ', a_an, key_type))
