'Hash and sign the passed-in bytes.
This requires the key to have a private component.  It performs
a PKCS1-SHA1 signature on the passed-in data.
@type bytes: str or L{bytearray} of unsigned bytes
@param bytes: The value which will be hashed and signed.
@rtype: L{bytearray} of unsigned bytes.
@return: A PKCS1-SHA1 signature on the passed-in data.'

def hashAndSign(self, bytes):

    hashBytes = SHA1(bytearray(bytes))
    prefixedHashBytes = self._addPKCS1SHA1Prefix(hashBytes)
    sigBytes = self.sign(prefixedHashBytes)
    return sigBytes
