Ciro Santilli @cirosantilli 40

Generalization of orthogonal group to preserve different bilinear forms. Important because the Lorentz group is $SO(1,3)$.

Being naughty and creative are correlated.

Some have actually been preserved: en.wikipedia.org/wiki/File:Blue_Box_in_museum.jpg

The only perfect cryptosystem!

The problem is that you need a shared key as large as the message.

Systems like advanced Encryption Standard allow us to encrypt things larger than the key, but the tradeoff is that they could be possibly broken, as don't have any provably secure symmetric-key algorithms as of 2020.

There aren't any 2020, except in the trivial one-time pad case where the key is as large as the message: crypto.stackexchange.com/questions/10815/how-do-we-prove-that-aes-des-etc-are-secure