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 Use the DTLS Profile to configure various DTLS parameters to attach to a SIP trunk group in support of WebRTC functionality.

Similar to TLS, the Datagram Transport Layer Security (DTLS) protocol provides authentication, data integrity, and confidentiality for communications between two applications over an unreliable User Datagram Protocol (UDP) connection. The Secure Real-time Transport Protocol (SRTP) provides encryption, message authentication and integrity, and replay protection to the RTP data in both unicast and multicast applications. DTLS-SRTP is an extension to the DTLS protocol, where DTLS acts as the key management protocol. DTLS protocol is also extended to negotiate the SRTP crypto suites and parameters for use with those keys.

WebRTC is a signaling protocol defined for real-time communication between web browsers. WebRTC uses the DTLS-SRTP protocol for media exchange between browsers. The SBC includes the following functionality:

  • Real-time communication between web browsers using DTLS-SRTP while inter-working with SIP networks.
  • DTLS on the media path for key management for SRTP-based media.
  • Self-signed certificates to secure and authenticate DTLS associations. DTLS connections are secured by the two browsers sharing self-signed certificates as part of the media connection during a DTLS handshake between the browsers. The certificates are authenticated by checking a fingerprint which is passed in the signaling path as part of the Session Description Protocol (SDP) negotiation.

The SBC includes crypto suites that define a set of ciphers (algorithms used for encrypting data) which allow the selection of an appropriate level of security. When a DTLS connection is established, the client and server exchange information about which cipher suites they have in common.

Command Syntax

% set profiles security dtlsProfile <profile name> 
	CertName <cert name>
	cipherSuite1 <cipher suite> 
	cipherSuite2 <cipher suite> 
	cipherSuite3 <cipher suite>
	cookieExchange <disabled | enabled>
	dtlsRole <client | server>
	handshakeTimer <1-60 seconds> 
	hashType <md2 | md5 | sha1 | sha224 | sha256 | sha384 | sha512>
	sessionResumpTimer <0-86400>
	v1_0 <disabled | enabled>
    v1_1 <disabled | enabled>
    v1_2 <disabled | enabled>


Command Parameters

The DTLS Profile Parameters are as shown below:

DTLS Profile Parameters

Parameter

Length/Range

Description

dtlsProfile1-23<profile name> – Name of DTLS profile.

CertName

1-23

<profile name> – Name of the Certificate used by this DTLS profile (default = defaultDtlsSBCCert).

cipherSuite1

N/A

Use this parameter to specify the first TLS Cipher Suite choice for this profile (default = rsa-with-aes-128-cbc-sha).

See the table Supported DTLS Crypto Suites below for the list of cipher suites.

cipherSuite2

N/A

Use this optional parameter to specify the second TLS Cipher Suite choice for this profile (default = nosuite).

See the table Supported DTLS Crypto Suites below for the list of cipher suites.


cipherSuite3

N/A

Use this optional parameter to specify the third TLS Cipher Suite choice for this profile (default = nosuite).

See the table Supported DTLS Crypto Suites below for the list of cipher suites.

cookieExchangeN/A

Use this flag to enable Cookie Exchange mechanism.

  • disabled
  • enabled (default)
dtlsRoleN/A

Specify DTLS role to use for this DTLS Profile.

  • client
  • server (default)

handshakeTimer

1-60

The time (in seconds) in which the DTLS handshake must be completed. The timer starts when the TCP connection is established. (default = 5)

hashTypeN/A

The allowed DTLS hash function for the specified DTLS Profile (default = sha1)

md2 | md5 | sha1 | sha224 | sha256 | sha384 | sha512

sessionResumpTimer

0-86400

The DTLS session resumption period (in seconds) for which cached sessions are retained. DTLS protocol allows successive connections to be created within one DTLS session (and the resumption of a session after a DTLS connection is closed or after a server card failover) without repeating the entire authentication and other setup steps for each connection, except when the space must be reclaimed for a new session. (default = 300)

v1_0N/A

DTLS protocol version 1.0 (see note below)

  • disabled
  • enabled (default)
v1_1N/A

DTLS protocol version 1.1 (see note below)

  • disabled  (default)
  • enabled
v1_2N/A

DTLS protocol version 1.2 (see note below)

  • disabled (default)
  • enabled

Crypto Suites

The following crypto suites are supported.

Supported TLS/DTLS Crypto Suites

Authentication Mechanism

Public/Private Key Pair

Confidentiality Cipher and Mode

Integrity Cipher

RSA-WITH-NULL-SHA

The integrity cipher used for the TLS Record protocol. 

RSANULLSHA-1

RSA-WITH-AES-128-CBC-SHA (default)

Confidentiality cipher and mode for the TLS Record protocol.

RSA

AES-128-CBC

SHA-1

RSA-WITH-AES-128-CBC-SHA-256

Confidentiality cipher and mode for the TLS Record protocol with SHA-256 as the hash function.

RSAAES-128-CBCSHA-256

RSA-WITH-AES-256-CBC-SHA

Confidentiality cipher and mode for the TLS Record protocol with AES 256 encryption.  

RSA

AES-256-CBC

SHA-1

RSA-WITH-AES-256-CBC-SHA-256*

Confidentiality cipher and mode for the TLS Record protocol with AES 256 encryption and SHA-256 as the hash function.

RSA

AES-256-CBC

SHA-256

TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384**

Confidentiality cipher and mode for the TLS Record with AES256 CBC and SHA384 as the hash function.

Note: The SBC 11.1 and later versions do not support tls_ecdh_ecdsa_with_aes_256_cbc_sha384. You must replace it with a valid Cipher before upgrading the SBC.

ECDH-ECDSA

AES-256-CBC

SHA-384

TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384**

Confidentiality cipher and mode for the TLS Record with AES256 GCM and SHA384 as the hash function.

ECDH-ECDSAAES-256-GCMSHA-384

TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA

Confidentiality cipher and mode for the TLS Record protocol using ECDHE (Elliptic Curve Diffie-Hellman key Exchange) with AES128 CBC and SHA as the hash function.

ECDHE-RSAAES-128-CBCSHA-1

TLS_ECDHE-RSA-WITH-AES-256-CBC-SHA-384*

Confidentiality cipher and mode for the TLS Record protocol using ECDHE (Elliptic Curve Diffie-Hellman key Exchange) with AES256 CBC and SHA384 as the hash function.

ECDHE-RSAAES-256-CBCSHA-384

TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256

Confidentiality cipher and mode for the TLS Record protocol using ECDHE (Elliptic Curve Diffie-Hellman key Exchange) with AES128 GCM and SHA as the hash function.

ECDHE-RSAAES-128-GCMSHA-256

TLS_ECDHE-RSA-WITH-AES-256-GCM-SHA-384*

Confidentiality cipher and mode for the TLS Record protocol using ECDHE (Elliptic Curve Diffie-Hellman key Exchange) with AES256 GCM and SHA384 as the hash function.

ECDHE-RSAAES-256-GCMSHA-384

TLS_RSA_WITH_AES_128_GCM_SHA256

Confidentiality cipher and mode for the TLS Record protocol with AES 128 GCM encryption and SHA-256 as the hash function.

RSAAES_128_GCMSHA-256

TLS_RSA_WITH_AES_256_GCM_SHA384

Confidentiality cipher and mode for the TLS Record protocol with AES 256 GCM encryption and SHA-384 as the hash function.

RSAAES_256_GCMSHA-384

TLS_AES_128_GCM_SHA256***

Confidentiality cipher and mode for the TLS Record with AES128 GCM and SHA256 as the hash function.

Unique to each TLS client and serverCTRSHA-256

TLS_AES_256_GCM_SHA384***

Confidentiality cipher and mode for the TLS Record with AES256 GCM and SHA384 as the hash function.

Unique to each TLS client and serverCTRSHA-384

TLS_CHACHA20_POLY1305_SHA256***

Confidentiality cipher and mode for the TLS Record with ChaCha20-Poly1305 and SHA256 as the hash function.

Unique to each TLS client and serverCTRSHA-256

*    To use this cipher, enable TLS version 1.2 in the TLS Profile.

**  To use this cipher, enable TLS version 1.2 in the TLS Profile and create SSL certificates using ECC keys.

*** To use this cipher, enable TLS version 1.3 in the TLS Profile.

Terms used in this table:

RSA – Authentication based on X.509 certificates using RSA public/private key pairs
AES-128 – Advanced Encryption Standard (128-bit key length)
CBC – Cipher Block Chaining
SHA – Secure Hash algorithm

Note

TLS 1.3 does not support RSA. Certificates generated with RSA will not work with TLS 1.3.

Note

When the FIPS-140-3 mode is enabled, you cannot use the algorithms whose key exchange method is RSA, including:

  • Rsa-with-null-sha
  • Rsa-with-aes-128-cbc-sha
  • Rsa-with-aes-128-cbc-sha-256
  • Rsa-with-aes-256-cbc-sha
  • Rsa-with-aes-256-cbc-sha-256
  • tls_rsa_with_aes_128_gcm_sha256
  • tls_rsa_with_aes_256_gcm_sha384
  • rsa-with-3des-ede-cbc-sha


FIPS Compliancy

The SBC 7.2.x release supports FIPS-140-2 and the 10.1.3 release supports FIPS-140-3. FIPS-140-2 is not supported in 10.1.3 and later releases and gets automatically converted to FIPS-140-3 as part of the upgrade.

To verify the current status of FIPS certification, contact the Global Support Assistance Center:

Command Examples

% show profiles security dtlsProfile defaultDtlsProfile
handshakeTimer     5;
sessionResumpTimer 300;
cipherSuite1       rsa-with-aes-128-cbc-sha;
dtlsRole           server;
hashType           sha1;
CertName           defaultDtlsSBCCert;
cookieExchange     enabled;
v1_0               enabled;
v1_1               disabled;
v1_2               disabled; 

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