Unrevert 5590 "description"(=(Auto)update libjingle 61834300->61901702).
BUG=N/A
R=xians@webrtc.org
Review URL: https://webrtc-codereview.appspot.com/9009004
git-svn-id: http://webrtc.googlecode.com/svn/trunk@5595 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/talk/session/media/externalhmac.h b/talk/session/media/externalhmac.h
new file mode 100644
index 0000000..47a195f
--- /dev/null
+++ b/talk/session/media/externalhmac.h
@@ -0,0 +1,91 @@
+/*
+ * libjingle
+ * Copyright 2014 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
+#define TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
+
+// External libsrtp HMAC auth module which implements methods defined in
+// auth_type_t.
+// The default auth module will be replaced only when the ENABLE_EXTERNAL_AUTH
+// flag is enabled. This allows us to access to authentication keys,
+// as the default auth implementation doesn't provide access and avoids
+// hashing each packet twice.
+
+// How will libsrtp select this module?
+// Libsrtp defines authentication function types identified by an unsigned
+// integer, e.g. HMAC_SHA1 is 3. Using authentication ids, the application
+// can plug any desired authentication modules into libsrtp.
+// libsrtp also provides a mechanism to select different auth functions for
+// individual streams. This can be done by setting the right value in
+// the auth_type of srtp_policy_t. The application must first register auth
+// functions and the corresponding authentication id using
+// crypto_kernel_replace_auth_type function.
+#if defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
+
+#ifdef SRTP_RELATIVE_PATH
+#include "crypto_types.h" // NOLINT
+#else
+#include "third_party/libsrtp/crypto/include/crypto_types.h"
+#endif // SRTP_RELATIVE_PATH
+
+#define EXTERNAL_HMAC_SHA1 HMAC_SHA1 + 1
+#define HMAC_KEY_LENGTH 20
+
+// The HMAC context structure used to store authentication keys.
+// The pointer to the key will be allocated in the external_hmac_init function.
+// This pointer is owned by srtp_t in a template context.
+typedef struct {
+ uint8_t key[HMAC_KEY_LENGTH];
+ int key_length;
+} external_hmac_ctx_t;
+
+err_status_t
+external_hmac_alloc(auth_t** a, int key_len, int out_len);
+
+err_status_t
+external_hmac_dealloc(auth_t* a);
+
+err_status_t
+external_hmac_init(external_hmac_ctx_t* state,
+ const uint8_t* key, int key_len);
+
+err_status_t
+external_hmac_start(external_hmac_ctx_t* state);
+
+err_status_t
+external_hmac_update(external_hmac_ctx_t* state, const uint8_t* message,
+ int msg_octets);
+
+err_status_t
+external_hmac_compute(external_hmac_ctx_t* state, const void* message,
+ int msg_octets, int tag_len, uint8_t* result);
+
+err_status_t
+external_crypto_init();
+
+#endif // defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
+#endif // TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_