SRTP - Secure Real-time Transport Protocol

SRTP is a security profile for RTP that adds confidentiality,message authentication, and replay protection to that protocol. SRTP is ideal for protecting Voice over IP traffic because it has no effect on voice quality and payload overhead is only minimally affected.

STRP - Secure Real-time Transport Protocol

PRODUCT AVAILABLILITY

ADT SRTP is a secure transmission feature, as defined in IETF RFC 3711. ADT SRTP is available in transportable “C” source code format as well as in library object format on all the Texas Instruments TMS320™ DSPs, and TNETV™ family of VoIP processors.

PRODUCT DESCRIPTION

SRTP - Secure Real-time Transport Protocol

SRTP, SRTCP*, & SRTCP-XR* are not separate protocols but are profiles of RTP. When security is being used, the packet payloads are encrypted.

RTP is specifically designed to handle the play-out requirements of real-time media streams through the use of time stamps and jitter buffering. Due to the real-time nature of the data streams, where requesting retransmissions is too costly in time, RTP is typically used in conjunction with UDP to provide low-overhead network communications between two end-points.
RFC 3550 identifies two components to the real-time transport: data transport and control. Data transport is handled by RTP while control is handled by Real Time Control Protocol (RTCP). RTCP, which can be used to help scale the network traffic to the available bandwidth, is optional.

An RTP packet identifies the media payload type (format) and its source. It also includes time stamps and sequence numbers that are used by the play-out side to handle lost or out of sequence packets. RTP provides for the use of multiple streams as in the case of a system that transmits both voice and video. The payload in an RTP payload contains the encoded voice or video information. The use of dynamically defined payload types allows RTP packets to carry virtually any type of media format.

* Adaptive Digital currently does not support RTCP.

Data sheet - .pdf

Secure Real-time Transport Protocol

FEATURES

Secure variants include support for:
1. Authentication Algorithm Types: HMAC-SHA1 and MD5
2. Key Definition Schemes: PSK, MKI, and FT
Encryption Algorithm Types: AES - CM, AES - F8
Supports multiple SRTP and SRCTP streams with same or different peers simultaneously
Master key used to derive session keys
SRTP (Secure RTP ) conform to IETF RFC 3711
eXpressDSP™ Algorithm Interoperability Standard (xDIAS) Compliant

PRODUCT SPECIFICATIONS

CPU Utilization - MIPS

C54x MIPS

SRTP
Payload Size (Bytes/10 msec)	Frame Rate (msec)	Encrypt		Encrypt + Auth		Decrypt		Decrypt + Auth
Payload Size (Bytes/10 msec)	Frame Rate (msec)	Avg	Peak	Avg	Peak	Avg	Peak	Avg	Peak
10	10	0.84	5.34	2.83	7.29	.086	5.36	2.87	7.36
	20	0.80	3.04	1.80	4.03	0.82	3.07	1.82	4.07
	30	0.54	2.03	1.21	2.70	0.55	2.05	1.22	2.72
80	10	3.91	8.38	6.35	10.84	3.94	8.43	6.38	10.85
	20	3.88	6.12	5.32	7.57	3.89	6.13	5.35	7.58
	30	3.87	5.36	5.12	6.62	3.88	5.37	5.14	6.63

C64x MIPS

SRTP
Payload Size (Bytes/10 msec)	Frame Rate (msec)	Encrypt		Encrypt + Auth		Decrypt		Decrypt + Auth
Payload Size (Bytes/10 msec)	Frame Rate (msec)	Avg	Peak	Avg	Peak	Avg	Peak	Avg	Peak
10	10	2.00.	10.12	2.55	10.65	.2.01	10.10	2.57	10.67
	20	1.96	6.00	2.23	6.28	1.96	6.00	2.24	6.29
	30	1.31	4.01	1.49	4.19	1.31	4.01	1.50	4.20
80	10	9.67	17.77	10.34	18.43	9.69	17.77	10.35	18.44
	20	9.64	13.68	10.02	14.06	9.64	13.68	10.03	14.07
	30	9.62	12.32	9.95	12.64	9.63	12.32	9.95	12.65

C64x+ MIPS

SRTP
Payload Size (Bytes/10 msec)	Frame Rate (msec)	Encrypt		Encrypt + Auth		Decrypt		Decrypt + Auth
Payload Size (Bytes/10 msec)	Frame Rate (msec)	Avg	Peak	Avg	Peak	Avg	Peak	Avg	Peak
10	10	1.97	10.04	2.48	10.52	1.98	10.01	2.49	10.52
	20	1.94	5.95	2.20	6.20	1.95	5.95	2.21	6.20
	30	1.30	3.97	1.47	4.14	1.30	3.96	1.47	4.14
80	10	9.65	17.72	10.26	18.29	9.65	17.68	10.27	18.29
	20	9.62	13.63	9.98	13.98	9.62	13.62	9.98	13.98
	30	9.61	12.28	9.91	12.58	9.61	12.28	9.91	12.58

Memory Utilization

C54x - All Memory usage is given in units of 16-bit word.

Memory Type	Usage
Shared Program	8963
Shared Data	2202
Per-Thread Scratch	160
Per-Channel Context Send	572
Per-Channel Context Receive	584

C64x - All Memory usage is given in units of byte.

Memory Type	Usage
Shared Program	12128
Shared Data	2357
Per-Thread Scratch	320
Per-Channel Context Send	1184
Per-Channel Context Receive	1184

C64x+ - All Memory usage is given in units of byte.

Memory Type	Usage
Shared Program	10464
Shared Data	2357
Per-Thread Scratch	320
Per-Channel Context Send	1184
Per-Channel Context Receive	1184

TERMINOLOGY

RTP - Real-time Transport Protocol

SRTP - Secure Real-time Transport Protocol

AES - Advanced Encryption Standard

AES CM - Advanced Encryption Standard counter mode

AES-f8 - AES in f8-mode, Universal Mobile Telecommunications System (UMTS) 3G mobile networks
use AES-f8.

Authentication Algorithm HMAC - Hashed message authentication code is characteristically used to authenticate that a message has not been changed during transit. Both parties to the message must have a shared secret key. The sender combines the key and the message into a string, produces a digest of the string by using an algorithm such as SHA-1 or MD5, and transmits the message and the digest. The receiver joins the shared key with the message, applies the appropriate algorithm, and runs a comparison between the digest thus obtained with that transmitted by the sender. If the digests are precisely the same, the message has not been tampered with.

Authentication Algorithm MD5 - Message Digest 5 is a widely used cryptographic hash function with a 128-bit hash value. As an Internet standard (RFC 1321), MD5 has been employed in a wide variety of security applications, and is also commonly used to check the integrity of files.

MKI - Master key identifier

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