Till Zimmermann

I think I've managed to build a more clear, universal and bidirectional (sign & verify) solution, however I'd like to keep it private until it's tested against at least one...

@Spomky That's the first thing I've considered when facing this bug, however I'd like to avoid `ext-gmp`, which is required by `fgrosse/phpasn1`, while phpseclib used in this impl is working...

@Spomky Isn't `Integer`, `Sequence` part of `phpasn1`, which represents the integers with gmp internally? However, I'd need to force my 'dependency manager' to ignore dependencies, which I'd like to avoid.

phpseclib ;-)