SSH Agent keys >4096 bit?

Milo gnupg at
Sat May 5 16:42:04 CEST 2012

On 05/05/2012 04:26 PM, Robert J. Hansen wrote:
> On 5/5/12 10:17 AM, Milo wrote:
>> "(...) This improves the strength of the algorithm when using keying
>> option 2, and _provides_ _backward_compatibility_ with DES with keying
>> option 3."
> One-key 3DES *is* DES. 

Obviously it's not. It's for example inappropriate to call single run of

> It's a DES encryption, decryption with that same
> key, then re-encryption with that same key.  One-key 3DES existed to
> allow institutions to bootstrap their infrastructure out of DES.  First
> they instituted one-key 3DES, which let them transparently upgrade their
> infrastructure without impacting business operations.  Once they were
> convinced their new 3DES infrastructure was working correctly, they
> switched to using two-key or three-key 3DES.  One-key 3DES was never
> meant to be used as anything more than an upgrade path.  The backwards
> compatibility of one-key 3DES was necessary for upgrade purposes, but
> once fully deployed 3DES has never had a problem with backwards
> compatibility.

And simply, you've just described ugly hack.

> What you said earlier was that 3DES had a bunch of keying hacks and
> backwards incompatibilities.  Neither is true.  All the various forms
> have been scrutinized quite closely and found to be solid.

And nothing changed in my stance. What's more 3DES is one big hack to
prolong life of outdated cipher.

If you are making such statements as above, try to not do this while
commenting heavily edited, original message.

> One-key 3DES has the benefit of backwards compatibility with DES, which
> is useful for upgrade purposes, but it's a gross misstatement of fact to
> claim that 3DES has a problem with backwards incompatibility.

I'm not interested (in context of this discussion) in benefits of this mode.


More information about the Gnupg-users mailing list