1=pod 2 3=head1 NAME 4 5SSL_CTX_set_tlsext_use_srtp, 6SSL_set_tlsext_use_srtp, 7SSL_get_srtp_profiles, 8SSL_get_selected_srtp_profile 9- Configure and query SRTP support 10 11=head1 SYNOPSIS 12 13 #include <openssl/srtp.h> 14 15 int SSL_CTX_set_tlsext_use_srtp(SSL_CTX *ctx, const char *profiles); 16 int SSL_set_tlsext_use_srtp(SSL *ssl, const char *profiles); 17 18 STACK_OF(SRTP_PROTECTION_PROFILE) *SSL_get_srtp_profiles(SSL *ssl); 19 SRTP_PROTECTION_PROFILE *SSL_get_selected_srtp_profile(SSL *s); 20 21=head1 DESCRIPTION 22 23SRTP is the Secure Real-Time Transport Protocol. OpenSSL implements support for 24the "use_srtp" DTLS extension defined in RFC5764. This provides a mechanism for 25establishing SRTP keying material, algorithms and parameters using DTLS. This 26capability may be used as part of an implementation that conforms to RFC5763. 27OpenSSL does not implement SRTP itself or RFC5763. Note that OpenSSL does not 28support the use of SRTP Master Key Identifiers (MKIs). Also note that this 29extension is only supported in DTLS. Any SRTP configuration will be ignored if a 30TLS connection is attempted. 31 32An OpenSSL client wishing to send the "use_srtp" extension should call 33SSL_CTX_set_tlsext_use_srtp() to set its use for all SSL objects subsequently 34created from an SSL_CTX. Alternatively a client may call 35SSL_set_tlsext_use_srtp() to set its use for an individual SSL object. The 36B<profiles> parameters should point to a NUL-terminated, colon delimited list of 37SRTP protection profile names. 38 39The currently supported protection profile names are: 40 41=over 4 42 43=item SRTP_AES128_CM_SHA1_80 44 45This corresponds to SRTP_AES128_CM_HMAC_SHA1_80 defined in RFC5764. 46 47=item SRTP_AES128_CM_SHA1_32 48 49This corresponds to SRTP_AES128_CM_HMAC_SHA1_32 defined in RFC5764. 50 51=item SRTP_AEAD_AES_128_GCM 52 53This corresponds to the profile of the same name defined in RFC7714. 54 55=item SRTP_AEAD_AES_256_GCM 56 57This corresponds to the profile of the same name defined in RFC7714. 58 59=back 60 61Supplying an unrecognised protection profile name will result in an error. 62 63An OpenSSL server wishing to support the "use_srtp" extension should also call 64SSL_CTX_set_tlsext_use_srtp() or SSL_set_tlsext_use_srtp() to indicate the 65protection profiles that it is willing to negotiate. 66 67The currently configured list of protection profiles for either a client or a 68server can be obtained by calling SSL_get_srtp_profiles(). This returns a stack 69of SRTP_PROTECTION_PROFILE objects. The memory pointed to in the return value of 70this function should not be freed by the caller. 71 72After a handshake has been completed the negotiated SRTP protection profile (if 73any) can be obtained (on the client or the server) by calling 74SSL_get_selected_srtp_profile(). This function will return NULL if no SRTP 75protection profile was negotiated. The memory returned from this function should 76not be freed by the caller. 77 78If an SRTP protection profile has been successfully negotiated then the SRTP 79keying material (on both the client and server) should be obtained via a call to 80L<SSL_export_keying_material(3)>. This call should provide a label value of 81"EXTRACTOR-dtls_srtp" and a NULL context value (use_context is 0). The total 82length of keying material obtained should be equal to two times the sum of the 83master key length and the salt length as defined for the protection profile in 84use. This provides the client write master key, the server write master key, the 85client write master salt and the server write master salt in that order. 86 87=head1 RETURN VALUES 88 89SSL_CTX_set_tlsext_use_srtp() and SSL_set_tlsext_use_srtp() return 0 on success 90or 1 on error. 91 92SSL_get_srtp_profiles() returns a stack of SRTP_PROTECTION_PROFILE objects on 93success or NULL on error or if no protection profiles have been configured. 94 95SSL_get_selected_srtp_profile() returns a pointer to an SRTP_PROTECTION_PROFILE 96object if one has been negotiated or NULL otherwise. 97 98=head1 SEE ALSO 99 100L<SSL_export_keying_material(3)> 101 102=head1 COPYRIGHT 103 104Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved. 105 106Licensed under the OpenSSL license (the "License"). You may not use 107this file except in compliance with the License. You can obtain a copy 108in the file LICENSE in the source distribution or at 109L<https://www.openssl.org/source/license.html>. 110 111=cut 112