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3733ce61a2
Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from https://github.com/openssl/openssl/pull/4205)
112 lines
4.1 KiB
Plaintext
112 lines
4.1 KiB
Plaintext
=pod
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=head1 NAME
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SSL_CTX_set_tlsext_use_srtp,
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SSL_set_tlsext_use_srtp,
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SSL_get_srtp_profiles,
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SSL_get_selected_srtp_profile
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- Configure and query SRTP support
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=head1 SYNOPSIS
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#include <openssl/srtp.h>
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int SSL_CTX_set_tlsext_use_srtp(SSL_CTX *ctx, const char *profiles);
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int SSL_set_tlsext_use_srtp(SSL *ssl, const char *profiles);
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STACK_OF(SRTP_PROTECTION_PROFILE) *SSL_get_srtp_profiles(SSL *ssl);
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SRTP_PROTECTION_PROFILE *SSL_get_selected_srtp_profile(SSL *s);
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=head1 DESCRIPTION
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SRTP is the Secure Real-Time Transport Protocol. OpenSSL implements support for
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the "use_srtp" DTLS extension defined in RFC5764. This provides a mechanism for
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establishing SRTP keying material, algorithms and parameters using DTLS. This
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capability may be used as part of an implementation that conforms to RFC5763.
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OpenSSL does not implement SRTP itself or RFC5763. Note that OpenSSL does not
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support the use of SRTP Master Key Identifiers (MKIs). Also note that this
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extension is only supported in DTLS. Any SRTP configuration will be ignored if a
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TLS connection is attempted.
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An OpenSSL client wishing to send the "use_srtp" extension should call
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SSL_CTX_set_tlsext_use_srtp() to set its use for all SSL objects subsequently
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created from an SSL_CTX. Alternatively a client may call
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SSL_set_tlsext_use_srtp() to set its use for an individual SSL object. The
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B<profiles> parameters should point to a NUL-terminated, colon delimited list of
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SRTP protection profile names.
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The currently supported protection profile names are:
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=over 4
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=item SRTP_AES128_CM_SHA1_80
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This corresponds to SRTP_AES128_CM_HMAC_SHA1_80 defined in RFC5764.
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=item SRTP_AES128_CM_SHA1_32
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This corresponds to SRTP_AES128_CM_HMAC_SHA1_32 defined in RFC5764.
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=item SRTP_AEAD_AES_128_GCM
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This corresponds to the profile of the same name defined in RFC7714.
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=item SRTP_AEAD_AES_256_GCM
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This corresponds to the profile of the same name defined in RFC7714.
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=back
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Supplying an unrecognised protection profile name will result in an error.
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An OpenSSL server wishing to support the "use_srtp" extension should also call
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SSL_CTX_set_tlsext_use_srtp() or SSL_set_tlsext_use_srtp() to indicate the
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protection profiles that it is willing to negotiate.
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The currently configured list of protection profiles for either a client or a
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server can be obtained by calling SSL_get_srtp_profiles(). This returns a stack
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of SRTP_PROTECTION_PROFILE objects. The memory pointed to in the return value of
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this function should not be freed by the caller.
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After a handshake has been completed the negotiated SRTP protection profile (if
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any) can be obtained (on the client or the server) by calling
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SSL_get_selected_srtp_profile(). This function will return NULL if no SRTP
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protection profile was negotiated. The memory returned from this function should
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not be freed by the caller.
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If an SRTP protection profile has been sucessfully negotiated then the SRTP
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keying material (on both the client and server) should be obtained via a call to
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L<SSL_export_keying_material(3)>. This call should provide a label value of
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"EXTRACTOR-dtls_srtp" and a NULL context value (use_context is 0). The total
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length of keying material obtained should be equal to two times the sum of the
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master key length and the salt length as defined for the protection profile in
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use. This provides the client write master key, the server write master key, the
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client write master salt and the server write master salt in that order.
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=head1 RETURN VALUES
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SSL_CTX_set_tlsext_use_srtp() and SSL_set_tlsext_use_srtp() return 0 on success
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or 1 on error.
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SSL_get_srtp_profiles() returns a stack of SRTP_PROTECTION_PROFILE objects on
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success or NULL on error or if no protection profiles have been configured.
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SSL_get_selected_srtp_profile() returns a pointer to an SRTP_PROTECTION_PROFILE
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object if one has been negotiated or NULL otherwise.
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=head1 SEE ALSO
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L<SSL_export_keying_material(3)>
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=head1 COPYRIGHT
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Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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