Backport was done with commit rC1d312bc65846 (for unknown reasons it did not show up in the list of bugs related to this bug; I added it by hand). Fix will go into 1.8.8.

I think that a backport to 1.8. also makes sense

Reading the code again, I think that some configuration of NKS card doesn't work well, when it has no certificates but keys (e.g. IDLM config).
I'm going to fix do_readkey as well (the approach #1).

In T5150#140039, @gniibe wrote:

With little (mostly no) knowledge of NKS card, I think I fixed this issue.

Thanks a lot for your time to locate the problem. I took the approach of #2.

I'm not sure why I thought that it would work now. With current master I get

$ gpg-connect-agent "SCD READKEY --info-only -- 39400430E38BB96F105B740A7119FE113578B59D" /bye
ERR 100663414 Invalid ID <SCD>

Fixed in master. I will backport to 2.2.

Seems to work now. I'm not sure whether I should close this issue because it's marked for backport.

Regarding a backport I think that I will eventually backport all app-*c to stable by source copying them. We have a quite stable internal API and thus it is easier to keep at least the card specific code in sync. I did some local work in this directory some time ago.

Thanks.

Thanks.

Thanks. May also happen if the first print_assuan_status fails.

Thanks. Fixed in master. Needs backport.

Thanks. Fixed in master.

Editor fault. The browser's editor is not like Emacs and here o my laptop the backspace key does not work as intended. I guess I was about to write ".. a back signature's usage flag".

what does "back signature's usage tool" mean? can we make an addition to the test suite that ensures that bad signatures will be rejected?

The fix was not fully correct because it considered a back signature's usage tool.

Done for master. Needs backport.