doc/man3/SSL_CTX_set_tlsext_use_srtp.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 SSL_CTX_set_tlsext_use_srtp,
   6 SSL_set_tlsext_use_srtp,
   7 SSL_get_srtp_profiles,
   8 SSL_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
  23 SRTP is the Secure Real-Time Transport Protocol. OpenSSL implements support for
  24 the "use_srtp" DTLS extension defined in RFC5764. This provides a mechanism for
  25 establishing SRTP keying material, algorithms and parameters using DTLS. This
  26 capability may be used as part of an implementation that conforms to RFC5763.
  27 OpenSSL does not implement SRTP itself or RFC5763. Note that OpenSSL does not
  28 support the use of SRTP Master Key Identifiers (MKIs). Also note that this
  29 extension is only supported in DTLS. Any SRTP configuration will be ignored if a
  30 TLS connection is attempted.
  31
  32 An OpenSSL client wishing to send the "use_srtp" extension should call
  33 SSL_CTX_set_tlsext_use_srtp() to set its use for all SSL objects subsequently
  34 created from an SSL_CTX. Alternatively a client may call
  35 SSL_set_tlsext_use_srtp() to set its use for an individual SSL object. The
  36 B<profiles> parameters should point to a NUL-terminated, colon delimited list of
  37 SRTP protection profile names.
  38
  39 The currently supported protection profile names are:
  40
  41 =over 4
  42
  43 =item SRTP_AES128_CM_SHA1_80
  44
  45 This corresponds to SRTP_AES128_CM_HMAC_SHA1_80 defined in RFC5764.
  46
  47 =item SRTP_AES128_CM_SHA1_32
  48
  49 This corresponds to SRTP_AES128_CM_HMAC_SHA1_32 defined in RFC5764.
  50
  51 =item SRTP_AEAD_AES_128_GCM
  52
  53 This corresponds to the profile of the same name defined in RFC7714.
  54
  55 =item SRTP_AEAD_AES_256_GCM
  56
  57 This corresponds to the profile of the same name defined in RFC7714.
  58
  59 =item SRTP_DOUBLE_AEAD_AES_128_GCM_AEAD_AES_128_GCM
  60
  61 This corresponds to the profile of the same name defined in RFC8723.
  62
  63 =item SRTP_DOUBLE_AEAD_AES_256_GCM_AEAD_AES_256_GCM
  64
  65 This corresponds to the profile of the same name defined in RFC8723.
  66
  67 =item SRTP_ARIA_128_CTR_HMAC_SHA1_80
  68
  69 This corresponds to the profile of the same name defined in RFC8269.
  70
  71 =item SRTP_ARIA_128_CTR_HMAC_SHA1_32
  72
  73 This corresponds to the profile of the same name defined in RFC8269.
  74
  75 =item SRTP_ARIA_256_CTR_HMAC_SHA1_80
  76
  77 This corresponds to the profile of the same name defined in RFC8269.
  78
  79 =item SRTP_ARIA_256_CTR_HMAC_SHA1_32
  80
  81 This corresponds to the profile of the same name defined in RFC8269.
  82
  83 =item SRTP_AEAD_ARIA_128_GCM
  84
  85 This corresponds to the profile of the same name defined in RFC8269.
  86
  87 =item SRTP_AEAD_ARIA_256_GCM
  88
  89 This corresponds to the profile of the same name defined in RFC8269.
  90
  91 =back
  92
  93 Supplying an unrecognised protection profile name will result in an error.
  94
  95 An OpenSSL server wishing to support the "use_srtp" extension should also call
  96 SSL_CTX_set_tlsext_use_srtp() or SSL_set_tlsext_use_srtp() to indicate the
  97 protection profiles that it is willing to negotiate.
  98
  99 The currently configured list of protection profiles for either a client or a
 100 server can be obtained by calling SSL_get_srtp_profiles(). This returns a stack
 101 of SRTP_PROTECTION_PROFILE objects. The memory pointed to in the return value of
 102 this function should not be freed by the caller.
 103
 104 After a handshake has been completed the negotiated SRTP protection profile (if
 105 any) can be obtained (on the client or the server) by calling
 106 SSL_get_selected_srtp_profile(). This function will return NULL if no SRTP
 107 protection profile was negotiated. The memory returned from this function should
 108 not be freed by the caller.
 109
 110 If an SRTP protection profile has been successfully negotiated then the SRTP
 111 keying material (on both the client and server) should be obtained via a call to
 112 L<SSL_export_keying_material(3)>. This call should provide a label value of
 113 "EXTRACTOR-dtls_srtp" and a NULL context value (use_context is 0). The total
 114 length of keying material obtained should be equal to two times the sum of the
 115 master key length and the salt length as defined for the protection profile in
 116 use. This provides the client write master key, the server write master key, the
 117 client write master salt and the server write master salt in that order.
 118
 119 These functions cannot be used with QUIC SSL objects.
 120
 121 =head1 RETURN VALUES
 122
 123 SSL_CTX_set_tlsext_use_srtp() and SSL_set_tlsext_use_srtp() return 0 on success
 124 or 1 on error.
 125
 126 SSL_get_srtp_profiles() returns a stack of SRTP_PROTECTION_PROFILE objects on
 127 success or NULL on error or if no protection profiles have been configured.
 128
 129 SSL_get_selected_srtp_profile() returns a pointer to an SRTP_PROTECTION_PROFILE
 130 object if one has been negotiated or NULL otherwise.
 131
 132 =head1 SEE ALSO
 133
 134 L<ssl(7)>,
 135 L<SSL_export_keying_material(3)>
 136
 137 =head1 COPYRIGHT
 138
 139 Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
 140
 141 Licensed under the Apache License 2.0 (the "License").  You may not use
 142 this file except in compliance with the License.  You can obtain a copy
 143 in the file LICENSE in the source distribution or at
 144 L<https://www.openssl.org/source/license.html>.
 145
 146 =cut