Maximum keypair length...

Barry Smith bnsmith001 at
Thu May 7 13:33:06 CEST 2020

Thank you for your excellent response.

I laid out my scenario.
RSA keys have the default maximum length of
8192 set at compile-time.
Perfect. that was the answer that
I was looking for.
My "risk scenario" was an attempt to understand the maximum defaults of the
current maximum protection available in the standard distributed packages.

>From the position of a data scientist, I am trying to compute the security
available. ;)

Thank you... 8196 on an RSA key. :)

On Fri, May 1, 2020, 12:01 Konstantin Ryabitsev <
konstantin at> wrote:

> On Thu, Apr 30, 2020 at 11:07:11PM -0400, Barry Smith via Gnupg-users
> wrote:
> > Let me continue by explaining some back up information for my
> > question.
> > - I am asking in terms of the latest standards implemented in distros and
> > Windows .exe auto-install packages.
> > - I am trying to create a group calendar file and app for a private
> group.
> > - Original concept for my project -- use an annual calendar file that has
> > December (year minus 1) to January (year plus 1), so 14 months of days. I
> > want one keypair per day for the group.
> I'm not sure what kind of risk scenario you're working against, but this
> sounds extreme and will probably have all sorts of usability corner
> cases.
> > SO, users, help!
> > I need to know the absolute longest key that GnuPG can create RIGHT
> > NOW.
> It depends on the algorithm. RSA keys have the default maximum length of
> 8192 set at compile-time. Elliptic Curve cryptography requires much
> shorter keys, so maximums will be different there.
> In general, the length of the key is only part of the picture when we're
> talking about encryption "strength." Many cryptographers consider RSA
> keys longer than 2048 bits to be a "feel-good security theatre", because
> classical computers are not likely to be able to successfully break
> 2048-bit keys in the foreseeable future, even given state-level funding.
> If/once we get to the point where quantum computers are powerful enough
> to defeat 2048-bit RSA, then we should consider all classical public-key
> crypto irreversibly compromised (RSA, DSA, ECC, etc) -- longer keypair
> lengths will merely buy a bit of time before failing to cryptanalysis.
> So, if you want decent modern-day encryption, use 256-bit ECC keys and
> don't worry about key lengths longer than 256 (or 4096 for RSA).
> -K
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