How to convert PHP pack function into Lua equivalent?

[MichelDeLigne]

Hello,

Does anyone know how I could convert the following PHP code to Lua?

Code:

MD5Salt = pack(
   "c*",
   0x86, 0x78, 0x45, 0xe9, 0x7c, 0x4e, 0x29, 0xdc,
   0xe5, 0x22, 0xb9, 0xa7, 0xd3, 0xa3, 0xe0, 0x7b,
   0x15, 0x2b, 0xff, 0xad, 0xdd, 0xbe, 0xd7, 0xf5,
   0xff, 0xd8, 0x42, 0xe9, 0x89, 0x5a, 0xd1, 0xe4
);

It looks like string.pack exists in Lua but I could not find it in LM.
I tried a few other approaches with some external libraries, but that failed, probably due to some incompatibilities.
I am a bit stuck here.
I need this to interface LM with a Buderus KM200, which uses an encrypted api.

Regards.
Michel.