Add Atmos read/write and untested MXF decryption tool.1.0-templates

15 files changed, 565 insertions, 3 deletions

diff --git a/run/tools/dcpdecryptmxf b/run/tools/dcpdecryptmxf
new file mode 100755
index 00000000..9caf5460
--- /dev/null
+++ b/run/tools/dcpdecryptmxf
@@ -0,0 +1,12 @@
+#!/bin/bash
+
+export LD_LIBRARY_PATH=build/src:build/asdcplib/src:$LD_LIBRARY_PATH
+if [ "$1" == "--debug" ]; then
+    shift
+    gdb --args build/tools/dcpdecryptmxf "$@"
+elif [ "$1" == "--valgrind" ]; then
+    shift
+    valgrind --tool="memcheck" --leak-check=full --show-reachable=yes build/tools/dcpdecryptmxf "$@"
+else
+    build/tools/dcpdecryptmxf "$@"
+fi
diff --git a/src/atmos_asset.cc b/src/atmos_asset.cc
index a8a595c3..eac01dcf 100644
--- a/src/atmos_asset.cc
+++ b/src/atmos_asset.cc
@@ -32,12 +32,27 @@
 */
 
 #include "atmos_asset.h"
+#include "atmos_asset_reader.h"
+#include "atmos_asset_writer.h"
 #include "exceptions.h"
 #include <asdcp/AS_DCP.h>
 
 using std::string;
+using boost::shared_ptr;
 using namespace dcp;
 
+AtmosAsset::AtmosAsset (Fraction edit_rate, int first_frame, int max_channel_count, int max_object_count, string atmos_id, int atmos_version)
+	: _edit_rate (edit_rate)
+	, _intrinsic_duration (0)
+	, _first_frame (first_frame)
+	, _max_channel_count (max_channel_count)
+	, _max_object_count (max_object_count)
+	, _atmos_id (atmos_id)
+	, _atmos_version (atmos_version)
+{
+
+}
+
 AtmosAsset::AtmosAsset (boost::filesystem::path file)
 	: Asset (file)
 {
@@ -57,6 +72,12 @@ AtmosAsset::AtmosAsset (boost::filesystem::path file)
 	_first_frame = desc.FirstFrame;
 	_max_channel_count = desc.MaxChannelCount;
 	_max_object_count = desc.MaxObjectCount;
+
+	char id[64];
+	Kumu::bin2UUIDhex (desc.AtmosID, ASDCP::UUIDlen, id, sizeof (id));
+	_atmos_id = id;
+
+	_atmos_version = desc.AtmosVersion;
 }
 
 string
@@ -64,3 +85,15 @@ AtmosAsset::pkl_type (Standard) const
 {
 	return "application/mxf";
 }
+
+shared_ptr<AtmosAssetReader>
+AtmosAsset::start_read () const
+{
+	return shared_ptr<AtmosAssetReader> (new AtmosAssetReader (this, key ()));
+}
+
+shared_ptr<AtmosAssetWriter>
+AtmosAsset::start_write (boost::filesystem::path file)
+{
+	return shared_ptr<AtmosAssetWriter> (new AtmosAssetWriter (this, file));
+}
diff --git a/src/atmos_asset.h b/src/atmos_asset.h
index 2e99e18b..8e9190c8 100644
--- a/src/atmos_asset.h
+++ b/src/atmos_asset.h
@@ -36,14 +36,21 @@
 
 #include "asset.h"
 #include "mxf.h"
+#include "atmos_asset_reader.h"
 
 namespace dcp {
 
+class AtmosAssetWriter;
+
 class AtmosAsset : public Asset, public MXF
 {
 public:
+	AtmosAsset (Fraction edit_rate, int first_frame, int max_channel_count, int max_object_count, std::string atmos_id, int atmos_version);
 	explicit AtmosAsset (boost::filesystem::path file);
 
+	boost::shared_ptr<AtmosAssetWriter> start_write (boost::filesystem::path file);
+	boost::shared_ptr<AtmosAssetReader> start_read () const;
+
 	std::string pkl_type (Standard) const;
 
 	Fraction edit_rate () const {
@@ -69,12 +76,24 @@ public:
 		return _max_object_count;
 	}
 
+	std::string atmos_id () const {
+		return _atmos_id;
+	}
+
+	int atmos_version () const {
+		return _atmos_version;
+	}
+
 private:
+	friend class AtmosAssetWriter;
+
 	Fraction _edit_rate;
 	int64_t _intrinsic_duration;
 	int _first_frame;
 	int _max_channel_count;
 	int _max_object_count;
+	std::string _atmos_id;
+	int _atmos_version;
 };
 
 }
diff --git a/src/atmos_asset_reader.h b/src/atmos_asset_reader.h
new file mode 100644
index 00000000..14806261
--- /dev/null
+++ b/src/atmos_asset_reader.h
@@ -0,0 +1,41 @@
+/*
+    Copyright (C) 2016 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    libdcp is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+#include "asset_reader.h"
+#include "atmos_frame.h"
+
+namespace dcp {
+
+typedef AssetReader<ASDCP::ATMOS::MXFReader, AtmosFrame> AtmosAssetReader;
+
+}
diff --git a/src/atmos_asset_writer.cc b/src/atmos_asset_writer.cc
new file mode 100644
index 00000000..eb0d608a
--- /dev/null
+++ b/src/atmos_asset_writer.cc
@@ -0,0 +1,109 @@
+/*
+    Copyright (C) 2016 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    libdcp is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+#include "atmos_asset_writer.h"
+#include "atmos_asset.h"
+#include "exceptions.h"
+#include "dcp_assert.h"
+#include "compose.hpp"
+#include "encryption_context.h"
+#include <asdcp/AS_DCP.h>
+
+using std::min;
+using std::max;
+using namespace dcp;
+
+struct AtmosAssetWriter::ASDCPState
+{
+	ASDCP::ATMOS::MXFWriter mxf_writer;
+	ASDCP::DCData::FrameBuffer frame_buffer;
+	ASDCP::WriterInfo writer_info;
+	ASDCP::ATMOS::AtmosDescriptor desc;
+};
+
+AtmosAssetWriter::AtmosAssetWriter (AtmosAsset* asset, boost::filesystem::path file)
+	: AssetWriter (asset, file, SMPTE)
+	, _state (new AtmosAssetWriter::ASDCPState)
+	, _asset (asset)
+{
+	_state->desc.EditRate = ASDCP::Rational (_asset->edit_rate().numerator, _asset->edit_rate().denominator);
+	_state->desc.FirstFrame = _asset->first_frame ();
+	_state->desc.MaxChannelCount = _asset->max_channel_count ();
+	_state->desc.MaxObjectCount = _asset->max_object_count ();
+
+	unsigned int c;
+	Kumu::hex2bin (_asset->atmos_id().c_str(), _state->desc.AtmosID, ASDCP::UUIDlen, &c);
+	DCP_ASSERT (c == ASDCP::UUIDlen);
+
+	_state->desc.AtmosVersion = 0;
+
+	_asset->fill_writer_info (&_state->writer_info, _asset->id(), SMPTE);
+}
+
+void
+AtmosAssetWriter::write (uint8_t const * data, int size)
+{
+	DCP_ASSERT (!_finalized);
+
+	if (!_started) {
+		Kumu::Result_t r = _state->mxf_writer.OpenWrite (_file.string().c_str(), _state->writer_info, _state->desc);
+		if (ASDCP_FAILURE (r)) {
+			boost::throw_exception (FileError ("could not open atmos MXF for writing", _file.string(), r));
+		}
+
+		_asset->set_file (_file);
+		_started = true;
+	}
+
+	_state->frame_buffer.Capacity (size);
+	_state->frame_buffer.Size (size);
+	memcpy (_state->frame_buffer.Data(), data, size);
+
+	ASDCP::Result_t const r = _state->mxf_writer.WriteFrame (_state->frame_buffer, _encryption_context->encryption(), _encryption_context->hmac());
+	if (ASDCP_FAILURE (r)) {
+		boost::throw_exception (MiscError (String::compose ("could not write atmos MXF frame (%1)", int (r))));
+	}
+
+	++_frames_written;
+}
+
+bool
+AtmosAssetWriter::finalize ()
+{
+	if (_started && ASDCP_FAILURE (_state->mxf_writer.Finalize())) {
+		boost::throw_exception (MiscError ("could not finalise atmos MXF"));
+	}
+
+	_asset->_intrinsic_duration = _frames_written;
+	return AssetWriter::finalize ();
+}
diff --git a/src/atmos_asset_writer.h b/src/atmos_asset_writer.h
new file mode 100644
index 00000000..e494b779
--- /dev/null
+++ b/src/atmos_asset_writer.h
@@ -0,0 +1,73 @@
+/*
+    Copyright (C) 2016 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    libdcp is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+/** @file  src/atmos_asset_writer.h
+ *  @brief AtmosAssetWriter class.
+ */
+
+#include "asset_writer.h"
+#include "types.h"
+#include "atmos_frame.h"
+#include <boost/shared_ptr.hpp>
+#include <boost/filesystem.hpp>
+
+namespace dcp {
+
+class AtmosAsset;
+
+/** @class AtmosAssetWriter
+ *  @brief A helper class for writing to AtmosAssets.
+ *
+ *  Objects of this class can only be created with AtmosAsset::start_write().
+ */
+class AtmosAssetWriter : public AssetWriter
+{
+public:
+	void write (uint8_t const * data, int size);
+	bool finalize ();
+
+private:
+	friend class AtmosAsset;
+
+	AtmosAssetWriter (AtmosAsset *, boost::filesystem::path);
+
+	/* do this with an opaque pointer so we don't have to include
+	   ASDCP headers
+	*/
+	struct ASDCPState;
+	boost::shared_ptr<ASDCPState> _state;
+
+	AtmosAsset* _asset;
+};
+
+}
diff --git a/src/atmos_frame.h b/src/atmos_frame.h
new file mode 100644
index 00000000..763875bd
--- /dev/null
+++ b/src/atmos_frame.h
@@ -0,0 +1,49 @@
+/*
+    Copyright (C) 2016 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    libdcp is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+/** @file  src/atmos_frame.h
+ *  @brief AtmosFrame class.
+ */
+
+#ifndef LIBDCP_ATMOS_FRAME_H
+#define LIBDCP_ATMOS_FRAME_H
+
+#include "frame.h"
+
+namespace dcp {
+
+typedef Frame<ASDCP::ATMOS::MXFReader, ASDCP::DCData::FrameBuffer> AtmosFrame;
+
+}
+
+#endif
diff --git a/src/decryption_context.h b/src/decryption_context.h
index e3d3ce1e..fb8342cf 100644
--- a/src/decryption_context.h
+++ b/src/decryption_context.h
@@ -31,6 +31,9 @@
     files in the program, then also delete it here.
 */
 
+#ifndef LIBDCP_DECRYPTION_CONTEXT_H
+#define LIBDCP_DECRYPTION_CONTEXT_H
+
 #include "key.h"
 #include <boost/optional.hpp>
 
@@ -55,3 +58,5 @@ private:
 };
 
 }
+
+#endif
diff --git a/src/frame.h b/src/frame.h
index 54b74e55..f20a1bb3 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -31,6 +31,9 @@
     files in the program, then also delete it here.
 */
 
+#ifndef LIBDCP_FRAME_H
+#define LIBDCP_FRAME_H
+
 #include "decryption_context.h"
 #include "exceptions.h"
 #include <asdcp/KM_fileio.h>
@@ -73,3 +76,5 @@ private:
 };
 
 }
+
+#endif
diff --git a/src/mono_picture_asset.cc b/src/mono_picture_asset.cc
index a6643bc0..407a3614 100644
--- a/src/mono_picture_asset.cc
+++ b/src/mono_picture_asset.cc
@@ -176,7 +176,7 @@ MonoPictureAsset::start_write (boost::filesystem::path file, Standard standard,
 shared_ptr<MonoPictureAssetReader>
 MonoPictureAsset::start_read () const
 {
-	return shared_ptr<MonoPictureAssetReader> (new MonoPictureAssetReader (this));
+	return shared_ptr<MonoPictureAssetReader> (new MonoPictureAssetReader (this, key ()));
 }
 
 string
diff --git a/src/sound_asset.cc b/src/sound_asset.cc
index 11fd4b2f..74d41212 100644
--- a/src/sound_asset.cc
+++ b/src/sound_asset.cc
@@ -201,7 +201,7 @@ SoundAsset::start_write (boost::filesystem::path file, Standard standard)
 shared_ptr<SoundAssetReader>
 SoundAsset::start_read () const
 {
-	return shared_ptr<SoundAssetReader> (new SoundAssetReader (this));
+	return shared_ptr<SoundAssetReader> (new SoundAssetReader (this, key ()));
 }
 
 string
diff --git a/src/stereo_picture_asset.cc b/src/stereo_picture_asset.cc
index 9a21b72b..4bbf7268 100644
--- a/src/stereo_picture_asset.cc
+++ b/src/stereo_picture_asset.cc
@@ -86,7 +86,7 @@ StereoPictureAsset::start_write (boost::filesystem::path file, Standard standard
 shared_ptr<StereoPictureAssetReader>
 StereoPictureAsset::start_read () const
 {
-	return shared_ptr<StereoPictureAssetReader> (new StereoPictureAssetReader (this));
+	return shared_ptr<StereoPictureAssetReader> (new StereoPictureAssetReader (this, key ()));
 }
 
 bool
diff --git a/src/wscript b/src/wscript
index 63c65905..f24064be 100644
--- a/src/wscript
+++ b/src/wscript
@@ -37,6 +37,7 @@ def build(bld):
              asset.cc
              asset_writer.cc
              atmos_asset.cc
+             atmos_asset_writer.cc
              certificate_chain.cc
              certificate.cc
              colour_conversion.cc
@@ -103,6 +104,8 @@ def build(bld):
               asset_reader.h
               asset_writer.h
               atmos_asset.h
+              atmos_asset_reader.h
+              atmos_asset_writer.h
               certificate_chain.h
               certificate.h
               chromaticity.h
diff --git a/tools/dcpdecryptmxf.cc b/tools/dcpdecryptmxf.cc
new file mode 100644
index 00000000..e640620a
--- /dev/null
+++ b/tools/dcpdecryptmxf.cc
@@ -0,0 +1,207 @@
+/*
+    Copyright (C) 2016 Carl Hetherington <cth@carlh.net>
+
+    This file is part of libdcp.
+
+    libdcp is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    libdcp is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
+
+    In addition, as a special exception, the copyright holders give
+    permission to link the code of portions of this program with the
+    OpenSSL library under certain conditions as described in each
+    individual source file, and distribute linked combinations
+    including the two.
+
+    You must obey the GNU General Public License in all respects
+    for all of the code used other than OpenSSL.  If you modify
+    file(s) with this exception, you may extend this exception to your
+    version of the file(s), but you are not obligated to do so.  If you
+    do not wish to do so, delete this exception statement from your
+    version.  If you delete this exception statement from all source
+    files in the program, then also delete it here.
+*/
+
+#include "encrypted_kdm.h"
+#include "decrypted_kdm.h"
+#include "decryption_context.h"
+#include "key.h"
+#include "util.h"
+#include "atmos_asset.h"
+#include "atmos_frame.h"
+#include "atmos_asset_reader.h"
+#include "atmos_asset_writer.h"
+#include "exceptions.h"
+#include <asdcp/AS_DCP.h>
+#include <boost/foreach.hpp>
+#include <getopt.h>
+#include <string>
+
+using std::string;
+using std::cerr;
+using std::cout;
+using boost::optional;
+using boost::shared_ptr;
+
+static void
+help (string n)
+{
+	cerr << "Syntax: " << n << " [OPTION] <MXF>]\n"
+	     << "  -v, --version      show DCP-o-matic version\n"
+	     << "  -h, --help         show this help\n"
+	     << "  -o, --output       output filename\n"
+	     << "  -k, --kdm          KDM file\n"
+	     << "  -p, --private-key  private key file\n";
+}
+
+int
+atmos (
+	ASDCP::ATMOS::MXFReader& reader,
+	boost::filesystem::path output_file,
+	dcp::DecryptedKDM kdm
+	)
+{
+	ASDCP::WriterInfo info;
+	if (ASDCP_FAILURE (reader.FillWriterInfo (info))) {
+		cerr << "Could not read ATMOS MXF information\n";
+		exit (EXIT_FAILURE);
+	}
+
+	if (!info.EncryptedEssence) {
+		cerr << "MXF is not encrypted!\n";
+		exit (EXIT_FAILURE);
+	}
+
+	char key_buffer[64];
+	Kumu::bin2UUIDhex (info.CryptographicKeyID, ASDCP::UUIDlen, key_buffer, sizeof (key_buffer));
+	string const key_id = key_buffer;
+
+	optional<dcp::Key> key;
+	BOOST_FOREACH (dcp::DecryptedKDMKey const & i, kdm.keys()) {
+		if (i.id() == key_id) {
+			key = i.key();
+		}
+	}
+
+	if (!key) {
+		cerr << "Could not find key in KDM.\n";
+		exit (EXIT_FAILURE);
+	}
+
+	dcp::DecryptionContext dc (key.get());
+
+	ASDCP::ATMOS::AtmosDescriptor desc;
+	if (ASDCP_FAILURE (reader.FillAtmosDescriptor (desc))) {
+		cerr << "could not read ATMOS descriptor.\n";
+		exit (EXIT_FAILURE);
+	}
+
+	ASDCP::DCData::FrameBuffer buffer (Kumu::Megabyte);
+
+	for (size_t i = 0; i < desc.ContainerDuration; ++i) {
+		reader.ReadFrame (i, buffer, dc.decryption(), 0);
+	}
+
+	return 0;
+}
+
+int
+main (int argc, char* argv[])
+{
+	optional<boost::filesystem::path> output_file;
+	optional<boost::filesystem::path> kdm_file;
+	optional<boost::filesystem::path> private_key_file;
+
+	int option_index = 0;
+	while (true) {
+		struct option long_options[] = {
+			{ "version", no_argument, 0, 'v' },
+			{ "help", no_argument, 0, 'h' },
+			{ "output", required_argument, 0, 'o'},
+			{ "kdm", required_argument, 0, 'k'},
+			{ "private-key", required_argument, 0, 'p'},
+			{ 0, 0, 0, 0 }
+		};
+
+		int c = getopt_long (argc, argv, "vho:k:p:", long_options, &option_index);
+
+		if (c == -1) {
+			break;
+		}
+
+		switch (c) {
+		case 'v':
+			cout << "libdcp version " << LIBDCP_VERSION << "\n";
+			exit (EXIT_SUCCESS);
+		case 'h':
+			help (argv[0]);
+			exit (EXIT_SUCCESS);
+		case 'o':
+			output_file = optarg;
+			break;
+		case 'k':
+			kdm_file = optarg;
+			break;
+		case 'p':
+			private_key_file = optarg;
+			break;
+		}
+	}
+
+	if (optind >= argc) {
+		help (argv[0]);
+		exit (EXIT_FAILURE);
+	}
+
+	boost::filesystem::path input_file = argv[optind];
+
+	if (!output_file) {
+		cerr << "You must specify -o or --output\n";
+		exit (EXIT_FAILURE);
+	}
+
+	if (!kdm_file) {
+		cerr << "You must specify -k or --kdm\n";
+		exit (EXIT_FAILURE);
+	}
+
+	if (!private_key_file) {
+		cerr << "You must specify -p or --private-key\n";
+		exit (EXIT_FAILURE);
+	}
+
+	dcp::EncryptedKDM encrypted_kdm (dcp::file_to_string (kdm_file.get ()));
+	dcp::DecryptedKDM decrypted_kdm (encrypted_kdm, dcp::file_to_string (private_key_file.get()));
+
+	try {
+		dcp::AtmosAsset in (input_file);
+		shared_ptr<dcp::AtmosAssetReader> reader = in.start_read ();
+		dcp::AtmosAsset out (
+			in.edit_rate(),
+			in.first_frame(),
+			in.max_channel_count(),
+			in.max_object_count(),
+			in.atmos_id(),
+			in.atmos_version()
+			);
+		shared_ptr<dcp::AtmosAssetWriter> writer = out.start_write (output_file.get());
+		for (int64_t i = 0; i < in.intrinsic_duration(); ++i) {
+			shared_ptr<const dcp::AtmosFrame> f = reader->get_frame (i);
+			writer->write (f->data(), f->size());
+		}
+	} catch (dcp::DCPReadError& e) {
+		cerr << "Unknown MXF format.\n";
+		return EXIT_FAILURE;
+	}
+
+	return 0;
+}
diff --git a/tools/wscript b/tools/wscript
index 1f04cd18..b3bb3a1f 100644
--- a/tools/wscript
+++ b/tools/wscript
@@ -49,3 +49,9 @@ def build(bld):
     obj.uselib = 'OPENJPEG CXML OPENMP ASDCPLIB_CTH BOOST_FILESYSTEM LIBXML++ XMLSEC1 OPENSSL'
     obj.source = 'dcpdumpsub.cc'
     obj.target = 'dcpdumpsub'
+
+    obj = bld(features='cxx cxxprogram')
+    obj.use = ['libdcp%s' % bld.env.API_VERSION]
+    obj.uselib = 'OPENJPEG CXML OPENMP ASDCPLIB_CTH BOOST_FILESYSTEM LIBXML++ XMLSEC1 OPENSSL'
+    obj.source = 'dcpdecryptmxf.cc'
+    obj.target = 'dcpdecryptmxf'