SSH login via GPG authentication subkey

.gnupg/gpg-agent.conf

@@ -1,3 +1,4 @@
 enable-ssh-support
 default-cache-ttl 3600
 max-cache-ttl 7200
+pinentry-program /usr/bin/pinentry-curses

.gnupg/sshcontrol

@@ -1 +1,2 @@
-8870E499C64EEB7720EBA5A442F4FE90129BFAE3
+8870E499C64EEB7720EBA5A442F4FE90129BFAE3
+

.zshrc

@@ -79,8 +79,16 @@ alias lt='ls -lath'
 alias config='/usr/bin/git --git-dir=$HOME/.cfg/ --work-tree=$HOME'
 config config --local status.showUntrackedFiles no
 
-# GPG with SSH auth capabilities 
-export SSH_AUTH_SOCK=$(gpgconf --list-dirs agent-ssh-socket)
+unset SSH_AGENT_PID
+if [ "${gnupg_SSH_AUTH_SOCK_by:-0}" -ne $$ ]; then
+  export SSH_AUTH_SOCK="$(gpgconf --list-dirs agent-ssh-socket)"
+fi
+export GPG_TTY=$(tty)
+gpg-connect-agent updatestartuptty /bye >/dev/null
+
+export KEYGRIP=8870E499C64EEB7720EBA5A442F4FE90129BFAE3
+# Sometimes gpg has a bug and needs to re-import key
+alias gbye='gpg-connect-agent "delete_key $KEYGRIP" /bye'
 
 if [ -f ~/.aliases ]; then
     . ~/.aliases