Implement ClearKey message format as JSON.

media/cdm/json_web_key.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_CDM_JSON_WEB_KEY_H_
 #define MEDIA_CDM_JSON_WEB_KEY_H_
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "media/base/media_export.h"
+#include "media/base/media_keys.h"
 
 namespace media {
 
+// The ClearKey license request format (ref:
+// https://dvcs.w3.org/hg/html-media/raw-file/default/encrypted-media/encrypted-media.html#clear-key)
+// is a JSON object containing the following members:
+//   "kids" : An array of key IDs. Each element of the array is the base64url
+//            encoding of the octet sequence containing the key ID value.
+//   "type" : The requested SessionType.
+// An example:
+//   { "kids":["67ef0gd8pvfd0","77ef0gd8pvfd0"], "type":"temporary" }
+
+// The ClearKey license format is a JSON Web Key (JWK) Set containing
+// representation of the symmetric key to be used for decryption.
+// For each JWK in the set, the parameter values are as follows:
+//   "kty" (key type)  : "oct" (octet sequence)
+//   "alg" (algorithm) : "A128KW" (AES key wrap using a 128-bit key)
+//   "k" (key value)   : The base64url encoding of the octet sequence
+//                       containing the symmetric key value.
+//   "kid" (key ID)    : The base64url encoding of the octet sequence
+//                       containing the key ID value.
+// The JSON object may have an optional "type" member value, which may be
+// any of the SessionType values. If not specified, the default value of
+// "temporary" is used.
 // A JSON Web Key Set looks like the following in JSON:
-//   { "keys": [ JWK1, JWK2, ... ] }
+//   { "keys": [ JWK1, JWK2, ... ], "type":"temporary" }
 // A symmetric keys JWK looks like the following in JSON:
 //   { "kty":"oct",
+//     "alg":"A128KW",
 //     "kid":"AQIDBAUGBwgJCgsMDQ4PEA",
 //     "k":"FBUWFxgZGhscHR4fICEiIw" }
+
 // There may be other properties specified, but they are ignored.
 // Ref: http://tools.ietf.org/html/draft-ietf-jose-json-web-key and:
 // http://tools.ietf.org/html/draft-jones-jose-json-private-and-symmetric-key
-//
-// For EME WD, both 'kid' and 'k' are base64 encoded strings, without trailing
-// padding.
 
 // Vector of [key_id, key_value] pairs. Values are raw binary data, stored in
 // strings for convenience.
 typedef std::pair<std::string, std::string> KeyIdAndKeyPair;
 typedef std::vector<KeyIdAndKeyPair> KeyIdAndKeyPairs;
 
 // Converts a single |key|, |key_id| pair to a JSON Web Key Set.
 MEDIA_EXPORT std::string GenerateJWKSet(const uint8* key, int key_length,
                                         const uint8* key_id, int key_id_length);
 
 // Extracts the JSON Web Keys from a JSON Web Key Set. If |input| looks like
-// a valid JWK Set, then true is returned and |keys| is updated to contain
-// the list of keys found. Otherwise return false.
+// a valid JWK Set, then true is returned and |keys| and |session_type| are
+// updated to contain the values found. Otherwise return false.
 MEDIA_EXPORT bool ExtractKeysFromJWKSet(const std::string& jwk_set,
-                                        KeyIdAndKeyPairs* keys);
+                                        KeyIdAndKeyPairs* keys,
+                                        MediaKeys::SessionType* session_type);
+
+// Create a license request message for the |key_id| and |session_type|
+// specified. Currently ClearKey generates a message for each key individually,
+// so no need to take a list of |key_id|'s. |license| is updated to contain the
+// resulting JSON string.
+MEDIA_EXPORT void CreateLicenseRequest(const uint8* key_id,
+                                       int key_id_length,
+                                       MediaKeys::SessionType session_type,
+                                       std::vector<uint8>* license);
+
+// Extract the first key from the license request message. Returns true if
+// |license| is a valid license request and contains at least one key,
+// otherwise false and |first_key| is not touched.
+MEDIA_EXPORT bool ExtractFirstKeyIdFromLicenseRequest(
+    const std::vector<uint8>& license,
+    std::vector<uint8>* first_key);
 
 }  // namespace media
 
 #endif  // MEDIA_CDM_JSON_WEB_KEY_H_