Secure RTP (SRTP) and UST Reference Implementations

David A. McGrew

Cisco Systems, Inc.

[email protected]

This package provides an implementation of the Secure Real-time Transport Protocol (SRTP), the Universal Security Transform (UST), and a supporting cryptographic kernel. These mechanisms are documented in the Internet Drafts in the doc/ subdirectory. The SRTP API is documented in include/srtp.h, and the library is in libsrtp.a (after compilation).

Some notable modifications were done on this package, listed below:

• The package is now using cmake to build almost exclusively

• test are not being build yet

• docs are still being build with a makefile

• include path of "config.h" has been changed in all source and header files; it is now "srtp/config.h"

• The include files have been moved and the source files changed to reflect this change. This is to accomodate local project inclusion (using it via a sub_directory in cmake; see example below)

• installation in the system is currently not possible; I've only tested the static library output so far

• the config.h is autogenerated in the CMAKE_CURRENT_BINARY_DIR/include/srtp/

This is because it is meant to be used locally to your project and not installed on the system; I might change it to make it possible to do a cmake install as well, but not now.

so assuming:

• your project dependencies are in a directory called vendor
• the cmake variable ${libraries} is being used in target_link_libraries()
• the cmake variable ${include_dirs} is being used as set_target_properties(myproj INCLUDE_DIRECTORIES)

in your CMakeLists.txt:

• add_subdirectory(vendor/libsrtp)
• list(APPEND include_dirs "${CMAKE_CURRENT_SOURCE_DIR}/vendor/libsrtp/include")
• list(APPEND include_dirs "${CMAKE_BINARY_DIR}/vendor/libsrtp/include") (This is for the autogenerated config file)
• list(APPEND libraries "libsrtp")

use in your code like so:

#include <srtp/srtp.h>

int main(int argc, char** argv)
{
	srtp_t session;
	srtp_policy_t policy;
	uint8_t key[30];
	
	srtp_init();

	crypto_policy_set_rtp_default(&policy.rtp);
	crypto_policy_set_rtcp_default(&policy.rtcp);

	crypto_get_random(key, 30);

	...
}

don't forget to read the original README as well