This is a litte script written in python 3.6.2, which generates you a mask and a byte signature out of a IDA Signature.
Example Usage: [ IDA-Signature ]
[ Input ] => A3 ? ? ? ? C7 05 ? ? ? ? ? ? ? ? E8 ? ? ? ? 59 C3 6A ?
[ Mask ]
[ Output ] => x????xx????????x????xxx?
[ Byte-Signature ]
[ Output ] => \xA3\x00\x00\x00\x00\xC7\x05\x00\x00\x00\x00\x00\x00\x00\x00\xE8\x00\x00\x00\x00\x59\xC3\x6A\x00