Copyright (C) 2021, Axis Communications AB, Lund, Sweden. All Rights Reserved.

Signed Video Framework

This repository holds the framework code of the feature Signed Video. The Signed Video feature secures the video from tampering after signing by adding cryptographic signatures to the video. Each video frame is hashed and signatures are generated repeatedly based on these hashes using a private key set by the signer. The signature data added to the video does not affect the video rendering. The data is added in a Supplemental Enhancement Information (SEI) NALU with type "user data unregistered". This SEI has a UUID of 5369676e-6564-2056-6964-656f2e2e2e30 in hexadecimal.

A more detailed description of the Signed Video feature is found in feature-description.

File structure

signed-video-framework
├── lib
|   ├── plugins
|   |   ├── threaded-signing
|   |   |   └── plugin.c
|   |   └── unthreaded-signing
|   |       └── plugin.c
|   ├── src
|   |   ├── includes
|   |   |   └── public header files
|   |   └── source files
|   └── vendors
|       └── axis-communications
|           └── source files
└── tests

The repository is split into a library and tests. The library is further organized in source code, plugins and vendors. The source code includes all necessary source files for both signing and validation, and there is no conceptual difference in building the library for signing or for validation.

Signing is commonly device specific with separate calls for, e.g., reading and using private keys. Therefore, the framework uses the concept of signing plugins which implements a set of interfaces. The framework comes with both a threaded and an unthreaded signing plugin.

Further, the framework allows for vendor specific metadata. Adding that on the signing side, and interpreting it on the validation side is controlled through vendor specific code.

For instructions on how to use the APIs to integrate the Signed Video Framework in either a signing or a validation application, see lib/. Example applications are available in the signed-video-framework-examples repository.

Releases

There are no pre-built releases. The user is encouraged to build the library from a release tag.

The check tests here in Github run on a Linux platform. Further, integration of the shared library is tested on a Linux platform for both signing and validation, whereas on Windows only validation is tested.

Getting started

The repository uses meson + ninja as default build method. Further, OpenSSL is used for cryptographic operations and to run unittests you need libcheck.

• meson Getting meson and ninja. Meson version 0.47.0 or newer is required.
• OpenSSL The default library to handle keys, hashes and signatures. OpenSSL version 1.1.1 or newer is required.
• libcheck The framework for unittests

Build Instructions

Below are meson instructions on how to build for either signing or validation. For help on meson usage see mesonbuild.com. The meson instructions in this repository will create a shared library named libsigned-video-framework.

Configure with meson

meson path/to/signed-video-framework path/to/build/folder

will generate compile instructions for ninja and put them in a folder located at path/to/build/folder. The framework comes with an option to build with debug prints

meson -Ddebugprints=true path/to/signed-video-framework path/to/build/folder

With the --prefix meson option it is possible to specify an arbitrary location to where the shared library is installed.

meson --prefix /absolute/path/to/your/local/installs path/to/signed-video-framework path/to/build/folder

Compile and install the shared library

To compile signed-video-framework using ninja

ninja -C path/to/build/folder

and the object file is located at path/to/build/folder/lib/src/libsigned-video-framework.so. To install the shared library run

meson install -C build

The library, named libsigned-video-framework, will be installed where libraries are installed, or at path/to/your/local/installs if you configured meson with --prefix. The header files will be located in a sub-folder of includes named signed-video-framework.

Example build commands on Linux

1. Configure and compile into ./build without installing from the top level

meson . build
ninja -C build

2. Configure, compile and install in ./my_installs/ from the parent folder of signed-video-framework/

meson --prefix $PWD/my_installs signed-video-framework build
meson install -C build

Configure, build and run unittests

Nothing extra is needed. Hence, to build and run the unittests call

meson . build
ninja -C build test

Alternatively, you can run the script tests/test_checks.sh and the unittests will run both with and without debug prints. Note that you need libcheck installed as well.

License

MIT License