[Gnuk-users] Ed25519 SSH key not working for gnupg > 2.1.6

[Jonathan Schleifer]

Am 09.05.2016 um 03:14 schrieb NIIBE Yutaka <gniibe at fsij.org>:

> Please compare yours.  I use 'hd' to print out in hexadecimal.  It's
> same as "od -x".
> 
> =========================
>    $ gpg2 --card-status
> 
>    Reader ...........: 234B:0000:FSIJ-1.1.9-87193059:0
>    Application ID ...: D276000124010200FFFE871930590000
>    Version ..........: 2.0
>    Manufacturer .....: unmanaged S/N range
>    Serial number ....: 87193059
>    Name of cardholder: Yutaka Niibe
>    Language prefs ...: ja
>    Sex ..............: male
>    URL of public key : http://www.gniibe.org/gniibe.asc
>    Login data .......: gniibe
>    Signature PIN ....: not forced
>    Key attributes ...: ed25519 cv25519 ed25519
>    Max. PIN lengths .: 127 127 127
>    PIN retry counter : 3 3 3
>    Signature counter : 0
>    Signature key ....: 249C B377 1750 745D 5CDD  323C E267 B052 364F 028D
>          created ....: 2015-08-12 07:10:48
>    Encryption key....: E228 AB42 0F73 3B1D 712D  E50C 850A F040 D619 F240
>          created ....: 2015-08-12 07:10:48
>    Authentication key: E63F 31E6 F203 20B5 D796  D266 5F91 0521 FAA8 05B1
>          created ....: 2015-08-12 07:16:14
>    General key info..: pub  ed25519/364F028D 2015-08-12 NIIBE Yutaka
> <gniibe at fsij.org>
>    sec>  ed25519/364F028D  created: 2015-08-12  expires: never
>                            card-no: FFFE 87193059
>    ssb>  ed25519/FAA805B1  created: 2015-08-12  expires: never
>                            card-no: FFFE 87193059
>    ssb>  cv25519/D619F240  created: 2015-08-12  expires: never
>                            card-no: FFFE 87193059
> 
> Since I'm using internal CCID driver, "Reader" is somehow cryptic.  It
> is composed by USB IDs, USB serial string and card number.
> 
> All three keys are identified by gpg frontend correctly.  Those data
> get through:  Gnuk Token -> scdaemon -> gpg-agent -> gpg
> 
> I have public key data by gpg frontend:
> 
>    $ gpg2 --list-secret-key --with-keygrip 364F028D
>    sec>  ed25519/364F028D 2015-08-12 [SC]
>          Keygrip = EB51C6F2AE531C6EF01EE0B7F3D5D4BC97455CE9
>          Card serial no. = FFFE 87193059
>    uid         [  full  ] NIIBE Yutaka <gniibe at fsij.org>
>    uid         [  full  ] NIIBE Yutaka <gniibe at debian.org>
>    ssb>  ed25519/FAA805B1 2015-08-12 [A]
>          Keygrip = 279D2DD3B00D6189EFEFB558850D434F44C9AFC8
>    ssb>  cv25519/D619F240 2015-08-12 [E]
>          Keygrip = 48245603DF3AE20A3088D7D010E77FAD2D464277
> 
> When I ask gpg-agent to get public-key of auth key in libgcrypt S-exp,
> it works.  The parameter 'q' is the public key and 33 is the length
> of byte of the public key.  The length is 33 because it starts by the
> prefix of @ (=0x40).
> 
>    $ gpg-connect-agent "readkey
> 279D2DD3B00D6189EFEFB558850D434F44C9AFC8" /bye | hd
>    00000000  44 20 28 31 30 3a 70 75  62 6c 69 63 2d 6b 65 79  |D
> (10:public-key|
>    00000010  28 33 3a 65 63 63 28 35  3a 63 75 72 76 65 37 3a
> |(3:ecc(5:curve7:|
>    00000020  45 64 32 35 35 31 39 29  28 35 3a 66 6c 61 67 73
> |Ed25519)(5:flags|
>    00000030  35 3a 65 64 64 73 61 29  28 31 3a 71 33 33 3a 40
> |5:eddsa)(1:q33:@|
>    00000040  ec 67 8f 79 9a e3 7d fe  fa fc 20 9e ec 54 f7 b8
> |.g.y..}... ..T..|
>    00000050  9f 7c 3a 8c 44 77 6c 82  af ee d9 07 58 f4 17 4c
> |.|:.Dwl.....X..L|
>    00000060  29 29 29 0a 4f 4b 0a                              |))).OK.|
>    00000067
> 
> I can also get same answer when I ask the public-key to scdaemon
> (through gpg-agent).
> 
>    $ gpg-connect-agent "scd readkey OPENPGP.3" /bye | hd
>    00000000  44 20 28 31 30 3a 70 75  62 6c 69 63 2d 6b 65 79  |D
> (10:public-key|
>    00000010  28 33 3a 65 63 63 28 35  3a 63 75 72 76 65 37 3a
> |(3:ecc(5:curve7:|
>    00000020  45 64 32 35 35 31 39 29  28 35 3a 66 6c 61 67 73
> |Ed25519)(5:flags|
>    00000030  35 3a 65 64 64 73 61 29  28 31 3a 71 33 33 3a 40
> |5:eddsa)(1:q33:@|
>    00000040  ec 67 8f 79 9a e3 7d fe  fa fc 20 9e ec 54 f7 b8
> |.g.y..}... ..T..|
>    00000050  9f 7c 3a 8c 44 77 6c 82  af ee d9 07 58 f4 17 4c
> |.|:.Dwl.....X..L|
>    00000060  29 29 29 0a 4f 4b 0a                              |))).OK.|
>    00000067

Until here, everything is correct. Instead of cv25519, I have rsa4096, though.

> I ask gpg-agent to get the public key of auth key in the format of SSH
> through ssh's socket:
> 
>    $ ssh-add -L
>    ssh-ed25519
> AAAAC3NzaC1lZDI1NTE5AAAAIOxnj3ma433++vwgnuxU97iffDqMRHdsgq/u2QdY9BdM
> cardno:FFFE87193059

And this is where it fails:

obuolys:~$ SSH_AUTH_SOCK="/Users/js/.gnupg/S.gpg-agent.ssh" ssh-add -L
error fetching identities for protocol 1: agent refused operation
error fetching identities for protocol 2: invalid format
The agent has no identities.
obuolys:~$ 

> Same data (except comment) can be gotten by gpg front end (of 2.1.12,
> new feature).
> 
>    $ gpg2 --export-ssh-key FAA805B1
>    ssh-ed25519
> AAAAC3NzaC1lZDI1NTE5AAAAIOxnj3ma433++vwgnuxU97iffDqMRHdsgq/u2QdY9BdM
> openpgp:0xFAA805B1

This works as well.

So, what else can I try?

--
Jonathan