Re: Re-sign subkey binding with changed digest?
> On 8 Jan 2020, at 20:05, Phil Pennock via Gnupg-users > wrote: > > How do I re-sign the subkey binding for a [S] signing subkey, to keep > the same key but make the association from the main key be with SHA256 > please? Have you tried changing the subkey expiry? Or does that reuse the same hash? A ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re-sign subkey binding with changed digest?
So, this SHA-1 mess is "fun".
To get a fresh self-sig user ID signature on the main key, I can do
this:
gpg --expert --cert-digest-algo SHA256 --sign-key ${KEYID:?}
The `--expert` overrides the "already signed" safety check, letting you
confirm that yes you really want this. Alas, it seems that
`--ask-cert-expire` is not enough, it no-ops out.
For sub-key bindings, for encryption keys it's easy: just generate a new
encryption sub-key, let it be signed with a modern hash, and future
messages encrypted to you will just use the new subkey.
For non-encryption subkeys, I'm looking really at signing subkeys: it
seems useful to make sure that existing signatures can continue to be
verified.
How do I re-sign the subkey binding for a [S] signing subkey, to keep
the same key but make the association from the main key be with SHA256
please?
Thanks,
-Phil
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Re: What are some threats against which OpenPGP smartcards are useful?
Notice that some features, like the metal contact toggle on some yubikey can mitigate the problem of having an attacker with full local access. You then have to touch the key each time you want to use it, so illegitimate access would be noticed. Le 8 janvier 2020 13:51:58 GMT+01:00, Andrew Gallagher a écrit : >On 07/01/2020 22:58, Christoph Groth wrote: >> How about the alternative of keeping small USB keycards (like a >Yubikey >> nano) permanently plugged into the machines that you are using? >> Assuming that you trust the keycards to keep their secrets, wouldn’t >> that provide at least the advantage of a much shorter passphrase? >Are >> there any security disadvantages of such a scheme? > >That effectively uses the smartcard as a hardware security module, >which >does have some advantages. The disadvantages are that if an attacker >has >code execution access to your machine they still have full access to >use >the key material. However, they cannot exfiltrate that key material, so >any malfeasance must be performed on your machine directly, which makes >it noisy. That may or may not be a deterrent, depending on your threat >model. It is more secure than having your private keys on disk, it just >may not be sufficiently secure. > >-- >Andrew Gallagher -- Envoyé de /e/ Mail.___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: What are some threats against which OpenPGP smartcards are useful?
I think this can be configured: ykman openpgp touch enc on ykman openpgp touch sig on Franck Le 8 janvier 2020 18:35:20 GMT+01:00, Andrew Gallagher a écrit : >On 2020/01/08 17:29, Franck Routier (perso) wrote: >> Notice that some features, like the metal contact toggle on some >yubikey >> can mitigate the problem of having an attacker with full local >access. >> You then have to touch the key each time you want to use it, so >> illegitimate access would be noticed. > >On my yubikey at least, the touch contact is only used for the FIDO 2FA >- the PGP smartcard feature is secured by PIN as per any other >smartcard. > >-- >Andrew Gallagher -- Envoyé de /e/ Mail.___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: What are some threats against which OpenPGP smartcards are useful?
On 2020/01/08 17:29, Franck Routier (perso) wrote: > Notice that some features, like the metal contact toggle on some yubikey > can mitigate the problem of having an attacker with full local access. > You then have to touch the key each time you want to use it, so > illegitimate access would be noticed. On my yubikey at least, the touch contact is only used for the FIDO 2FA - the PGP smartcard feature is secured by PIN as per any other smartcard. -- Andrew Gallagher ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: Forward entire gnupg $HOME
On Mon, Sep 09, 2019 at 11:39:01PM +0200, Ángel wrote: > On 2019-09-05 at 08:59 +0200, john doe wrote: > > On 9/4/2019 10:41 PM, Andre Klärner wrote: > > > I usually use my workstation to do everything, but since I can't > > > access my mailbox via NFS anymore (different story), I resorted to > > > sshing into my email server, and doing all the mailing needs right > > > there, locally. > (...) > > > > The obvious solution would be to use mutt on your work station! :) > > Using mutt locally seems much simpler than forcing gnupg to work that > way. You mention that you can no longer access your mailbox via nfs, > but since you can ssh to the email server, maybe you could mount it > with sshfs? There are some problems with sshfs, however, such as slowness and locking. It would probably be better to run an imap daemon on your mail server, and have mutt use imap to access the mailbox. signature.asc Description: PGP signature ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: What are some threats against which OpenPGP smartcards are useful?
On 07/01/2020 22:58, Christoph Groth wrote: > How about the alternative of keeping small USB keycards (like a Yubikey > nano) permanently plugged into the machines that you are using? > Assuming that you trust the keycards to keep their secrets, wouldn’t > that provide at least the advantage of a much shorter passphrase? Are > there any security disadvantages of such a scheme? That effectively uses the smartcard as a hardware security module, which does have some advantages. The disadvantages are that if an attacker has code execution access to your machine they still have full access to use the key material. However, they cannot exfiltrate that key material, so any malfeasance must be performed on your machine directly, which makes it noisy. That may or may not be a deterrent, depending on your threat model. It is more secure than having your private keys on disk, it just may not be sufficiently secure. -- Andrew Gallagher signature.asc Description: OpenPGP digital signature ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: What are some threats against which OpenPGP smartcards are useful?
Wiktor Kwapisiewicz wrote: > There is one feature of smartcards that's hard to reproduce otherwise: > once you pull the smartcard out of the port the attacker can't use it. > > (...) Thanks, that’s a good point! So if one’s concern is signing or authentication, this is indeed useful. However, if one’s concern is protecting encrypted secrets that are regularly accessed (like passwords) and can be thus stolen, there seems to be less of a gain. signature.asc Description: PGP signature ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Re: What are some threats against which OpenPGP smartcards are useful?
Robert J. Hansen wrote: > On 2020-01-06 18:26, Christoph Groth wrote: > > > > But then he also mentions his 128-bit passphrase and that he would > > be OK to publish his (passphrase-protected) private key in > > a newspaper. Why then not store it on the disks of multiple > > computers? > > Hint: because the phrase "forensics lab" is extremely important in > what I wrote. > > (...) Thanks a lot for the explaination, Rob. Now I understand what you meant. > But, outside of that laboratory environment, I didn't -- still > don't -- need to use a smartcard. Usually I just keep the key on the > hard drive of whatever machine I'm using. How about the alternative of keeping small USB keycards (like a Yubikey nano) permanently plugged into the machines that you are using? Assuming that you trust the keycards to keep their secrets, wouldn’t that provide at least the advantage of a much shorter passphrase? Are there any security disadvantages of such a scheme? By the way, I would be still interested in expert opinion about the last paragraph of my original mail, in case someone could spare the time. signature.asc Description: PGP signature ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
