With --pinentry-mode=loopback GnuPG 2.1 asks passphrase
twice on symmetric encryption, while GnuPG 1.x does that only once (look
at the GET_HIDDEN lines below). Though I suppose the second GET_HIDDEN is a
confirmation, it is useless for clients since they already know if confirmation
is needed, and incompatible with the code working with GnuPG 1.x.
$ gpg2 --command-fd=1 --status-fd=1 --pinentry-mode=loopback --symmetric -o
/dev/null < /dev/null
gpg: NOTE: THIS IS A DEVELOPMENT VERSION! gpg: It is only intended for test purposes and should NOT be gpg: used in a production environment or with production keys! [GNUPG:] NEED_PASSPHRASE_SYM 7 3 2 [GNUPG:] GET_HIDDEN passphrase.enter test [GNUPG:] GOT_IT [GNUPG:] GET_HIDDEN passphrase.enter test [GNUPG:] GOT_IT [GNUPG:] BEGIN_ENCRYPTION 2 7 [GNUPG:] END_ENCRYPTION $ gpg --command-fd=1 --status-fd=1 --symmetric -o /dev/null < /dev/null [GNUPG:] NEED_PASSPHRASE_SYM 3 3 2 [GNUPG:] GET_HIDDEN passphrase.enter test [GNUPG:] GOT_IT [GNUPG:] BEGIN_ENCRYPTION 0 3 [GNUPG:] END_ENCRYPTION