Handle keyinfo request (#44)

gpg: handle KEYINFO request

See https://git.gnupg.org/cgi-bin/gitweb.cgi?p=gnupg.git;a=blob;f=agent/command.c;h=9522f898997e95207d59122d056f0f0be03ccecb;hb=6bee88dd067e03e7767ceacf6a849d9ba38cc11d#l1027 for more details.

trezor_agent/gpg/agent.py

@@ -127,6 +127,12 @@ def handle_connection(conn):
         elif command == 'PKDECRYPT':
             sec = pkdecrypt(keygrip, conn)
             keyring.sendline(conn, b'D ' + sec)
+        elif command == 'KEYINFO':
+            keygrip, = args
+            # Dummy reply (mainly for 'gpg --edit' to succeed).
+            # For details, see GnuPG agent KEYINFO command help.
+            fmt = b'S KEYINFO {0} X - - - - - - -'
+            keyring.sendline(conn, fmt.format(keygrip))
         elif command == 'BYE':
             return
         else: