core: New flags GPGME_DECRYPT_UNWRAP and GPGME_ENCRYPT_WRAP.

* src/gpgme.h.in (GPGME_ENCRYPT_WRAP): New const.
(gpgme_decrypt_flags_t): New enum.
(GPGME_DECRYPT_VERIFY): New const
(GPGME_DECRYPT_UNWRAP): New const
(gpgme_op_decrypt_ext_start): New func.
(gpgme_op_decrypt_ext): New func.
* src/decrypt-verify.c (gpgme_op_decrypt_ext_start): New.
(gpgme_op_decrypt_ext): New.
(decrypt_verify_start): Add arg FLAGS.  Replace call to
engine_op_decrypt_verify by the plain decrypt with the flag set.
(gpgme_op_decrypt_verify_start): Pass the flag.
(gpgme_op_decrypt_verify): Pass the flag.
* src/decrypt.c (decrypt_start): Rename to ...
(_gpgme_decrypt_start): this.  Add arg FLAGS.  Pass FLAGS to
engine_op_decrypt.
(gpgme_op_decrypt_start): Adjust for chnage pass 0 for FLAG.
(gpgme_op_decrypt_start): Ditto.
* src/engine.c (_gpgme_engine_op_decrypt_verify): Remove.
(_gpgme_engine_op_decrypt): Add arg FLAGS.
* src/gpgme.def, src/libgpgme.vers: Add new functions.
* src/engine-backend.h (struct engine_ops): Remove member
'decrypt_verify'.  Add FLAGS to 'decrypt'.  Adjust all initialization.
* src/engine-uiserver.c (uiserver_decrypt): Remove.
(uiserver_decrypt_verify): Remove.
(_uiserver_decrypt): Rename to ...
(uiserver_decrypt): this.  Replace arg VERIFY by new arg FLAGS.
* src/engine-gpg.c (gpg_decrypt): Support GPGME_DECRYPT_UNWRAP.
(gpg_encrypt): Support GPGME_ENCRYPT_WRAP.

* tests/run-decrypt.c (main): New option --unwrap.
* tests/run-encrypt.c (main): New option --wrap.
--

Manual testing of that wrap/unwrap feature can be done this way:

 ./run-encrypt --verbose --key Alice /etc/motd > x
 ./run-decrypt --verbose --unwrap x > y
 ./run-encrypt --verbose --key Bob --wrap y > z

1. The message was first encrypted to Alice.
2. Alice decrypts the message receiving a valid OpenPGP message.
3. Alice encrypt that message to Bob

This will also work with encrypted and signed messages; the signature
will be kept intact during re-encryption.  Requires GnuPG 2.1.12.

Signed-off-by: Werner Koch <[email protected]>

1 files changed, 52 insertions, 0 deletions

diff --git a/doc/gpgme.texi b/doc/gpgme.texi
index fd1f9bc7..d5969b71 100644
--- a/doc/gpgme.texi
+++ b/doc/gpgme.texi
@@ -4890,6 +4890,53 @@ operation could be started successfully, and @code{GPG_ERR_INV_VALUE}
 if @var{cipher} or @var{plain} is not a valid pointer.
 @end deftypefun
 
+
+@deftypefun gpgme_error_t gpgme_op_decrypt_ext ( @
+            @w{gpgme_ctx_t @var{ctx}}, @
+            @w{gpgme_decrypt_flags_t @var{flags}}, @
+            @w{gpgme_data_t @var{cipher}}, @
+            @w{gpgme_data_t @var{plain}})
+
+The function @code{gpgme_op_decrypt_ext} is the same as
+@code{gpgme_op_decrypt_ext} but has an additional argument
+@var{flags}.  If @var{flags} is 0 both function behave identically.
+
+The value in @var{flags} is a bitwise-or combination of one or
+multiple of the following bit values:
+
+@table @code
+@item GPGME_DECRYPT_VERIFY
+The @code{GPGME_DECRYPT_VERIFY} symbol specifies that this function
+shall exacty act as @code{gpgme_op_decrypt_verify}.
+
+@item GPGME_DECRYPT_UNWRAP
+The @code{GPGME_DECRYPT_UNWRAP} symbol specifies that the output shall
+be an OpenPGP message with only the encryption layer removed.  This
+requires GnuPG 2.1.12 and works only for OpenPGP.  This is the
+counterpart to @code{GPGME_ENCRYPT_WRAP}.
+
+@end table
+
+The function returns the error codes as descriped for
+@code{gpgme_op_decrypt} respective @code{gpgme_op_encrypt}.
+@end deftypefun
+
+@deftypefun gpgme_error_t gpgme_op_decrypt_ext_start ( @
+            @w{gpgme_ctx_t @var{ctx}}, @
+            @w{gpgme_decrypt_flags_t @var{flags}}, @
+            @w{gpgme_data_t @var{cipher}}, @
+            @w{gpgme_data_t @var{plain}})
+
+The function @code{gpgme_op_decrypt_ext_start} initiates a
+@code{gpgme_op_decrypt_ext} operation.  It can be completed by calling
+@code{gpgme_wait} on the context.  @xref{Waiting For Completion}.
+
+The function returns the error code @code{GPG_ERR_NO_ERROR} if the
+operation could be started successfully, and @code{GPG_ERR_INV_VALUE}
+if @var{cipher} or @var{plain} is not a valid pointer.
+@end deftypefun
+
+
 @deftp {Data type} {gpgme_recipient_t}
 This is a pointer to a structure used to store information about the
 recipient of an encrypted text which is decrypted in a
@@ -5634,6 +5681,11 @@ On the receiving side, the use of this flag may slow down the
 decryption process because all available secret keys must be tried.
 This flag is only honored for OpenPGP encryption.
 
+@item GPGME_ENCRYPT_WRAP
+The @code{GPGME_ENCRYPT_WRAP} symbol specifies that the input is an
+OpenPGP message and not a plain data.  This is the counterpart to
+@code{GPGME_DECRYPT_UNWRAP}.
+
 @end table
 
 If @code{GPG_ERR_UNUSABLE_PUBKEY} is returned, some recipients in