ERROR key generation error: Unknown signature subpacket: 34 (error 905), gpg (GnuPG) 2.3.1 libgcrypt 1.9.3

[MuhtasimTanmoy]

While importing pgp key, the command below is generating this error:
keybase pgp select

Please refer to line number: 120 common/openpgpdefs.h as of gnupg-2.3.1

SIGSUBPKT_PREF_AEAD = 34, /* Preferred AEAD algorithms. */

[prertik]

I ran into this issue too.

[ppaeps]

Does Keybase not support Ed25519 OpenPGP keys?

I get this error when trying to add a new public key. I don't understand why the error message mentions "key generation". I don't need Keybase to generate a key. I need it to spit out a statement for me to sign.

[benmontour]

Same issue here when attempting to import ed25519 OpenPGP generated key using keybase pgp select --import

[markdascher]

I managed to workaround this issue by removing the preferred AEAD algorithms from the public key. Not sure if there's an better way to do it, but the setpref subcommand of gpg --edit-key works. You basically have to run showpref, then copy the whole list except for AEADs (and Uncompressed/Features, which are both implied) into a new setpref command, like this:

% gpg --edit-key mykey

gpg> showpref
[ultimate] (1). mykey
     Cipher: AES256, AES192, AES, 3DES
     AEAD: OCB, EAX
     Digest: SHA512, SHA384, SHA256, SHA224, SHA1
     Compression: ZLIB, BZIP2, ZIP, Uncompressed
     Features: MDC, AEAD, Keyserver no-modify

gpg> setpref AES256 AES192 AES 3DES SHA512 SHA384 SHA256 SHA224 SHA1 ZLIB BZIP2 ZIP
Set preference list to:
     Cipher: AES256, AES192, AES, 3DES
     AEAD: 
     Digest: SHA512, SHA384, SHA256, SHA224, SHA1
     Compression: ZLIB, BZIP2, ZIP, Uncompressed
     Features: MDC, Keyserver no-modify
Really update the preferences? (y/N) y

[ppaeps]

Unfortunately, this is not working for me.

I modified my public key as @markdascher suggested.

% gpg --edit-key B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B
[... do the thing ...]
% gpg --edit-key B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B
[...]
gpg> showpref
[ultimate] (1). Philip Paeps <philip@trouble.is>
     Cipher: AES256, AES192, AES, 3DES
     AEAD:
     Digest: SHA512, SHA384, SHA256, SHA224, SHA1
     Compression: ZLIB, BZIP2, ZIP, Uncompressed
     Features: MDC, Keyserver no-modify
[ultimate] (2)  Philip Paeps <philip@freebsd.org>
     Cipher: AES256, AES192, AES, 3DES
     AEAD:
     Digest: SHA512, SHA384, SHA256, SHA224, SHA1
     Compression: ZLIB, BZIP2, ZIP, Uncompressed
     Features: MDC, Keyserver no-modify

I verified that the AEAD prefs were actually gone by comparing the output of gpg --list-packets before and after:

% diff -u pubkey.asc.txt pubkey-no-aead.asc.txt
--- pubkey.asc.txt	2021-06-23 13:02:50.000000000 +0800
+++ pubkey-no-aead.asc.txt	2021-06-23 13:18:58.000000000 +0800
@@ -5,39 +5,37 @@
 	keyid: BB6D8A14AFE7D96B
 :user ID packet: "Philip Paeps <philip@trouble.is>"
 :signature packet: algo 22, keyid BB6D8A14AFE7D96B
-	version 4, created 1621924124, md5len 0, sigclass 0x13
-	digest algo 10, begin of digest 91 fe
+	version 4, created 1624424244, md5len 0, sigclass 0x13
+	digest algo 10, begin of digest 13 22
 	hashed subpkt 27 len 1 (key flags: 03)
 	hashed subpkt 9 len 4 (key expires after 2y37d5h32m)
+	hashed subpkt 23 len 1 (keyserver preferences: 80)
+	hashed subpkt 25 len 1 (primary user ID)
+	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
+	hashed subpkt 2 len 4 (sig created 2021-06-23)
 	hashed subpkt 11 len 4 (pref-sym-algos: 9 8 7 2)
-	hashed subpkt 34 len 2 (pref-aead-algos: 2 1)
 	hashed subpkt 21 len 5 (pref-hash-algos: 10 9 8 11 2)
 	hashed subpkt 22 len 3 (pref-zip-algos: 2 3 1)
-	hashed subpkt 30 len 1 (features: 07)
-	hashed subpkt 23 len 1 (keyserver preferences: 80)
-	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
-	hashed subpkt 2 len 4 (sig created 2021-05-25)
-	hashed subpkt 25 len 1 (primary user ID)
+	hashed subpkt 30 len 1 (features: 05)
 	subpkt 16 len 8 (issuer key ID BB6D8A14AFE7D96B)
 	data: [256 bits]
-	data: [256 bits]
+	data: [255 bits]
 :user ID packet: "Philip Paeps <philip@freebsd.org>"
 :signature packet: algo 22, keyid BB6D8A14AFE7D96B
-	version 4, created 1621924146, md5len 0, sigclass 0x13
-	digest algo 10, begin of digest c7 b2
-	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
-	hashed subpkt 2 len 4 (sig created 2021-05-25)
+	version 4, created 1624424254, md5len 0, sigclass 0x13
+	digest algo 10, begin of digest 8f e8
 	hashed subpkt 27 len 1 (key flags: 03)
 	hashed subpkt 9 len 4 (key expires after 2y37d5h32m)
+	hashed subpkt 23 len 1 (keyserver preferences: 80)
+	hashed subpkt 33 len 21 (issuer fpr v4 B851CD3AC248F2ED3E2CC18CBB6D8A14AFE7D96B)
+	hashed subpkt 2 len 4 (sig created 2021-06-23)
 	hashed subpkt 11 len 4 (pref-sym-algos: 9 8 7 2)
-	hashed subpkt 34 len 2 (pref-aead-algos: 2 1)
 	hashed subpkt 21 len 5 (pref-hash-algos: 10 9 8 11 2)
 	hashed subpkt 22 len 3 (pref-zip-algos: 2 3 1)
-	hashed subpkt 30 len 1 (features: 07)
-	hashed subpkt 23 len 1 (keyserver preferences: 80)
+	hashed subpkt 30 len 1 (features: 05)
 	subpkt 16 len 8 (issuer key ID BB6D8A14AFE7D96B)
-	data: [253 bits]
-	data: [255 bits]
+	data: [256 bits]
+	data: [256 bits]
 :public sub key packet:
 	version 4, algo 22, created 1621924204, expires 0
 	pkey[0]: [80 bits] ed25519 (1.3.6.1.4.1.11591.15.1)

Selecting that key from keybase select pgp --multi still returns the same error:

▶ ERROR key generation error: Unknown signature subpacket: 34 (error 905)

[chloeruka]

@ppaeps I ran into this just before when I added another uid via adduid using GnuPG on a key generated with Keybase; the answer in your case might be to remove any additional "Features" listed in the preferences. I couldn't find a list of feature switches from a quick google, but for me what worked was to append ks-modify no-mdc to the end of the preference string.

Example:

gpg --expert --edit-key YOURKEYID
gpg> setpref AES AES256 CAST5 3DES SHA256 SHA512 SHA1 RIPEMD160 ZIP ZLIB ks-modify no-mdc
Set preference list to:
     Cipher: AES, AES256, CAST5, 3DES
     AEAD:
     Digest: SHA256, SHA512, SHA1, RIPEMD160
     Compression: ZIP, ZLIB, Uncompressed
Really update the preferences? (y/N) y
gpg> save

And then I was able to keybase pgp update.

[ppaeps]

Hooray! That worked.

Thanks @chloeruka!

[nottoseethesun]

I have the same issue, but the fix that worked for @ppaeps is not working for me:

To try to fix, I did this:

setpref AES256 AES192 AES 3DES OCB EAX SHA512 SHA384 SHA256 SHA224 SHA1 ZLIB BZIP2 ZIP Uncompressed MDC ks-modify no-mdc

The pref set is accepted, I accept (y), quit and save. Then did keybase pgp update.

Still the same error when I try to select that key for keybase pgp select. It's on a YubiKey that's plugged into the computer.

More info:

gpg> showpref
[ultimate] (1). foobar (batbaz) <bar@bat.com>
     Cipher: AES256, AES192, AES, 3DES
     AEAD: OCB, EAX
     Digest: SHA512, SHA384, SHA256, SHA224, SHA1
     Compression: ZLIB, BZIP2, ZIP, Uncompressed
     Features: AEAD

gpg>

As a side note, I could not add "AEAD" in the prefs list, for it complained that it is an invalid option. But it always appears under "fetaures". Prior to the set, I had "Keyserver no-modify" (which I don't care about), and after the set, it is gone.

[ppaeps]

@nottoseethesun You want to remove the AEAD prefs from your list, so your setpref line should read:

setpref AES256 AES192 AES 3DES SHA512 SHA384 SHA256 SHA224 SHA1 ZLIB BZIP2 ZIP Uncompressed ks-modify no-mdc

As I understand it, the Features: line shows up automatically and lists AEAD if any AEAD forms (e.g. OCB, EAX) appear in the cipher preference list. Likewise, it'll list MDC unless ks-modify no-mdc is given, as suggested by @chloeruka.

[ppaeps]

@nottoseethesun Note that these manipulations shouldn't affect your YubiKey in any way. As I understand it, the preferences are part of the public key and your YubiKey really only cares about private keys. Having said that, it's been a while since I looked closely at OpenPGP.

Before uploading my public key anywhere (either with Keybase or anything else), I always very carefully check with gpg --list-packets what has changed. I like to store my public keys in Git and have this snippet in my .gitconfig:

[diff "asc"]
    textconv = "f(){ gpg --list-packets < \"$1\" | grep -v \"^# off=\"; }; f"

The output of that is very slightly more lucid than a big blob of base64. ;-)

I only uploaded public key with the modified cipher preference list to Keybase. Other sources of my public key have the previous preference list (i.e. the defaults as set by GnuPG when I generated the key). So far, this doesn't seem to have upset the delicate balance of the universe.

[nottoseethesun]

@ppaeps Thanks; got rid of AEAD as you suggested and now this key is working great with Keybase.

[yuliu]

Why doesn't Keybase fix this issue?

[chipbuster]

Can anyone give a short overview of the implications of changing the default settings as suggested by the current workaround? (Or a link to such documentation---google has pulled up many scattered and incomplete results, but nothing definitive).

I did find a gist that suggests that "reasonably secure defaults" are no-ks-modify and mdc, but I still don't know what these actually do.