Independent function signatures

[naim94a]

A bit more research is required to determine how IDA calculates function signatures. Calculating signatures independently would allow other tools (such as radare2, binary-ninja, Ghidra) to use the lumen server.

The signature is the md5 of the function's bytes and a bitmap of the same length.

Ideally, something like this:

fn calc_chksum(fn_bytes: &[u8]) -> [u8; 16] {
    let mut md5 = Md5::new();
    md5.update(fn_bytes);
    let bitmap = // work needed
    md5.update(&bitmap);
    md5.digest()
}

[jesterret]

Hi, just letting You know, in case You're still working on it, it's actually hash of function bytes, but all function & variable adresses are nulled, so
call sub_... (E8 BA AD F0 0D) turns into call $+5 (E8 00 00 00 00)
mov eax, dword_... (B8 BA AD F0 0D) turns into mov eax, 0 (B8 00 00 00 00)
and the other part is nulled array, where any place that got cleared from original function bytes is replaced with 0xFF
Hope it's clear enough, and that it will be helpful ;)

[TheDuchy]

@naim94a please DM me on Twitter at DuchyRE and let's make radare2 compatible!