import hashlib, sys, struct data= open(sys.argv[1], "rb").read() digest = hashlib.md5(data).digest() hdr = struct.pack(">4sI8x",b"IMD5",len(data)) f2 = open(sys.argv[2],"wb") f2.write(hdr) f2.write(digest) f2.write(data) f2.close()