[joeyh]

4096 is the largest key size gpg offers today. It was the largest key size gpg offered in 2009, which is why that's the key size I'm using now. In 1996 the largest key size pgp supported was probably 768 , which is why my first pgp key is that size. I know for sure that in 1999, the largest key I could manage to make was 2048. Looking back at those older keys, I would prefer if I could have chosen larger key sizes for them. So I suspect that in 10 years I will wish I could have used a 8196 or larger key today..

I suspect that gpg partly doesn't offer insanely large key sizes because then people like me will naively use them even if we don't need them. And perhaps partly because dealing with the math for such large numbers is harder to implement. I'd rather it offered much larger keys even if they came with warnings that it might make operations slow.

[joeyh]

Seems that if you're really paranoid, gpg --gen-key --batch with an approptiate batch file can make 8192 or larger keys. Currently trying to generate a 81920 bit key, for general giggles and to increase my NSA rating.

[moep]

Could you provide a sample batch file for this purpose? That’d be really helpful.

[TowerGuy74]

In 1998, the NSA required MIT to subborn their PGP. MIT publicly stated that at the time. NSA simultaneously banned the use of MIT's European confederate's version of PGP by U.S. citizens, and blocked access to that university's FTP from the U.S. Naturally, being overseas at the time, I downloaded the European version and, since it allowed creation of up-to 4096-bit keys with the option of manually-specifying non-standard lengths, I created a very large key which I saved to floppy disk.