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28 #ifndef TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
29 #define TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_
31 // External libsrtp HMAC auth module which implements methods defined in
33 // The default auth module will be replaced only when the ENABLE_EXTERNAL_AUTH
34 // flag is enabled. This allows us to access to authentication keys,
35 // as the default auth implementation doesn't provide access and avoids
36 // hashing each packet twice.
38 // How will libsrtp select this module?
39 // Libsrtp defines authentication function types identified by an unsigned
40 // integer, e.g. HMAC_SHA1 is 3. Using authentication ids, the application
41 // can plug any desired authentication modules into libsrtp.
42 // libsrtp also provides a mechanism to select different auth functions for
43 // individual streams. This can be done by setting the right value in
44 // the auth_type of srtp_policy_t. The application must first register auth
45 // functions and the corresponding authentication id using
46 // crypto_kernel_replace_auth_type function.
47 #if defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
49 #include "webrtc/base/basictypes.h"
50 #ifdef SRTP_RELATIVE_PATH
51 #include "auth.h" // NOLINT
53 #include "third_party/libsrtp/crypto/include/auth.h"
54 #endif // SRTP_RELATIVE_PATH
56 #define EXTERNAL_HMAC_SHA1 HMAC_SHA1 + 1
57 #define HMAC_KEY_LENGTH 20
59 // The HMAC context structure used to store authentication keys.
60 // The pointer to the key will be allocated in the external_hmac_init function.
61 // This pointer is owned by srtp_t in a template context.
63 uint8 key[HMAC_KEY_LENGTH];
65 } external_hmac_ctx_t;
67 err_status_t external_hmac_alloc(auth_t** a, int key_len, int out_len);
69 err_status_t external_hmac_dealloc(auth_t* a);
71 err_status_t external_hmac_init(external_hmac_ctx_t* state,
75 err_status_t external_hmac_start(external_hmac_ctx_t* state);
77 err_status_t external_hmac_update(external_hmac_ctx_t* state,
78 const uint8_t* message,
81 err_status_t external_hmac_compute(external_hmac_ctx_t* state,
87 err_status_t external_crypto_init();
89 #endif // defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
90 #endif // TALK_SESSION_MEDIA_EXTERNAL_HMAC_H_