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SRTP / RTSPS

Secure Real-time Transport Protocol (SRTP) and RTSP over TLS (RTSPS) are security extensions that protect real-time audio/video streaming.

SRTP​

SRTP secures media streams by encrypting and authenticating RTP traffic. It provides confidentiality, integrity, and replay protection for audio and video data while keeping latency low — which is critical for real-time media.

RTSPS​

RTSPS is the secure version of RTSP, where TLS encrypts RTSP signaling (similar to HTTPS for HTTP). It protects control-plane information such as stream URLs, session setup and control messages, credentials, and parameters from eavesdropping or tampering.

When and why to use them​

Low-latency secure unicast streaming​

In some unicast deployments, you can use RTSPS together with SRTP to transport media over RTP/UDP rather than over HTTPS/TCP. This avoids TCP retransmissions and head-of-line blocking, resulting in:

  • Lower end-to-end latency
  • More predictable timing under packet loss
  • Better suitability for live video

Multicast streaming​

In multicast scenarios, multiple receivers subscribe to the same stream:

  • You need SRTP because multicast traffic is visible to anyone on the network segment. Encryption ensures only authorized receivers can decode the media.
  • You can use RTSPS for secure session setup and key exchange, while the media itself is distributed efficiently via multicast.

Summary​

RTSPS secures control and signaling, while SRTP secures media. Together, they provide strong end-to-end protection for RTSP-based streaming while preserving low latency, making them well suited for secure unicast and multicast deployments.

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