Added support for callables; added base64 and hex string prototypes

[insomniacslk]

Encodings are another interesting type of data to match. While these could be matched with a regex, a more robust approach is to attempt the actual decoding. This could be slower than regex'es in certain cases.

I've added a callable argument, and made the regex optional, but at least one is required.

Examples:

$ ./hashid.py $(echo hashid | base64)
Analyzing 'aGFzaGlkCg=='
[+] Base64

$ ./hashid.py 414243 # the string 'ABC' as hex string
Analyzing '414243'
[+] CRC-24
[+] Hex string

[bburky]

Base64 and hex maybe sound ok, but I really think we could still implement these with a regex?

Hex can be matched with ^[a-fA-F0-9]+$ (or ^([a-fA-F0-9]{2})+$ to match only even length strings for actual bytes).

I think ^([a-zA-Z0-9+/]{4})*([a-zA-Z0-9+/]{4}|[a-zA-Z0-9+/]{2}==|[a-zA-Z0-9+/]{3}=)$ is a valid regex for base64. It checks the alphabet, that the length is a multiple of four, and that the last block is valid.

Including encodings may be something of a slippery slope. Should we include URL encoding too?

[insomniacslk]

These can totally be implemented with a regex, but I was suggesting at the same time an alternative method. Maybe in a separate commit? I think it's nice to have the option to use both, e.g. with a command line switch (--prefer-regex and --prefer-callable maybe?).

On the encodings - I'd say to start humble with these two, and add the others as soon as they're needed, in separate commits.

[bburky]

There's really no reason to use a callable though for these encodings. The regex is equivalent.

[insomniacslk]

I'll take it as a no. Code reverted to only use regexes

[psypanda]

Hey! Since I have almost no spare time at the moment I have added @bburky as a collaborator with push access to the repository.

[insomniacslk]

any joy here?