bcbd78bd24
Clarify offline usage of sessions and keys and implement implement CryptoSession to support additional crypto use cases. Change-Id: I418ffbb37e3036a2b5eea5a86ac88a5af1a9da07
273 lines
13 KiB
C++
273 lines
13 KiB
C++
/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef DRM_API_H_
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#define DRM_API_H_
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#include <utils/List.h>
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#include <utils/String8.h>
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#include <utils/Vector.h>
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#include <utils/KeyedVector.h>
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#include <utils/RefBase.h>
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#include <media/stagefright/foundation/ABase.h>
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// Loadable DrmEngine shared libraries should define the entry points
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// createDrmFactory and createCryptoFactory as shown below:
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//
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// extern "C" {
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// extern android::DrmFactory *createDrmFactory();
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// extern android::CryptoFactory *createCryptoFactory();
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// }
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namespace android {
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struct DrmPlugin;
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// DRMs are implemented in DrmEngine plugins, which are dynamically
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// loadable shared libraries that implement the entry points
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// createDrmFactory and createCryptoFactory. createDrmFactory
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// constructs and returns an instance of a DrmFactory object. Similarly,
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// createCryptoFactory creates an instance of a CryptoFactory object.
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// When a MediaCrypto or MediaDrm object needs to be constructed, all
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// available DrmEngines present in the plugins directory on the device
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// are scanned for a matching DrmEngine that can support the crypto
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// scheme. When a match is found, the DrmEngine's createCryptoPlugin and
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// createDrmPlugin methods are used to create CryptoPlugin or
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// DrmPlugin instances to support that DRM scheme.
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class DrmFactory {
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public:
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DrmFactory() {}
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virtual ~DrmFactory() {}
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// DrmFactory::isCryptoSchemeSupported can be called to determine
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// if the plugin factory is able to construct plugins that support a
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// given crypto scheme, which is specified by a UUID.
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virtual bool isCryptoSchemeSupported(const uint8_t uuid[16]) = 0;
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// Construct a DrmPlugin for the crypto scheme specified by UUID.
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virtual status_t createDrmPlugin(
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const uint8_t uuid[16], DrmPlugin **plugin) = 0;
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private:
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DrmFactory(const DrmFactory &);
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DrmFactory &operator=(const DrmFactory &);
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};
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class DrmPlugin {
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public:
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enum EventType {
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kDrmPluginEventProvisionRequired,
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kDrmPluginEventKeyNeeded,
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kDrmPluginEventKeyExpired,
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kDrmPluginEventVendorDefined
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};
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// Drm keys can be for offline content or for online streaming.
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// Offline keys are persisted on the device and may be used when the device
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// is disconnected from the network.
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enum KeyType {
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kKeyType_Offline,
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kKeyType_Streaming
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};
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DrmPlugin() {}
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virtual ~DrmPlugin() {}
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// Open a new session with the DrmPlugin object. A session ID is returned
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// in the sessionId parameter.
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virtual status_t openSession(Vector<uint8_t> &sessionId) = 0;
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// Close a session on the DrmPlugin object.
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virtual status_t closeSession(Vector<uint8_t> const &sessionId) = 0;
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// A key request/response exchange occurs between the app and a License
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// Server to obtain the keys required to decrypt the content. getKeyRequest()
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// is used to obtain an opaque key request blob that is delivered to the
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// license server.
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//
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// The init data passed to getKeyRequest is container-specific and its
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// meaning is interpreted based on the mime type provided in the mimeType
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// parameter to getKeyRequest. It could contain, for example, the content
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// ID, key ID or other data obtained from the content metadata that is required
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// in generating the key request.
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//
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// keyType specifes if the keys are to be used for streaming or offline content
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//
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// optionalParameters are included in the key request message to allow a
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// client application to provide additional message parameters to the server.
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//
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// If successful, the opaque key request blob is returned to the caller.
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virtual status_t
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getKeyRequest(Vector<uint8_t> const &sessionId,
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Vector<uint8_t> const &initData,
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String8 const &mimeType, KeyType keyType,
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KeyedVector<String8, String8> const &optionalParameters,
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Vector<uint8_t> &request, String8 &defaultUrl) = 0;
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// After a key response is received by the app, it is provided to the
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// Drm plugin using provideKeyResponse. Returns the id of the key set
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// in keySetId. The keySetId can be used by removeKeys or restoreKeys
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// when the keys are used for offline content.
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virtual status_t provideKeyResponse(Vector<uint8_t> const &sessionId,
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Vector<uint8_t> const &response,
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Vector<uint8_t> &keySetId) = 0;
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// Remove the persisted keys associated with an offline license for a session.
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virtual status_t removeKeys(Vector<uint8_t> const &keySetId) = 0;
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// Restore persisted offline keys into a new session. keySetId identifies
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// the keys to load, obtained from a prior call to provideKeyResponse().
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virtual status_t restoreKeys(Vector<uint8_t> const &sessionId,
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Vector<uint8_t> const &keySetId) = 0;
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// Request an informative description of the license for the session. The status
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// is in the form of {name, value} pairs. Since DRM license policies vary by
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// vendor, the specific status field names are determined by each DRM vendor.
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// Refer to your DRM provider documentation for definitions of the field names
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// for a particular DrmEngine.
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virtual status_t
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queryKeyStatus(Vector<uint8_t> const &sessionId,
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KeyedVector<String8, String8> &infoMap) const = 0;
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// A provision request/response exchange occurs between the app and a
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// provisioning server to retrieve a device certificate. getProvisionRequest
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// is used to obtain an opaque key request blob that is delivered to the
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// provisioning server.
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//
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// If successful, the opaque provision request blob is returned to the caller.
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virtual status_t getProvisionRequest(Vector<uint8_t> &request,
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String8 &defaultUrl) = 0;
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// After a provision response is received by the app, it is provided to the
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// Drm plugin using provideProvisionResponse.
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virtual status_t provideProvisionResponse(Vector<uint8_t> const &response) = 0;
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// A means of enforcing the contractual requirement for a concurrent stream
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// limit per subscriber across devices is provided via SecureStop. SecureStop
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// is a means of securely monitoring the lifetime of sessions. Since playback
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// on a device can be interrupted due to reboot, power failure, etc. a means
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// of persisting the lifetime information on the device is needed.
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//
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// A signed version of the sessionID is written to persistent storage on the
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// device when each MediaCrypto object is created. The sessionID is signed by
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// the device private key to prevent tampering.
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//
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// In the normal case, playback will be completed, the session destroyed and
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// the Secure Stops will be queried. The App queries secure stops and forwards
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// the secure stop message to the server which verifies the signature and
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// notifies the server side database that the session destruction has been
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// confirmed. The persisted record on the client is only removed after positive
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// confirmation that the server received the message using releaseSecureStops().
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virtual status_t getSecureStops(List<Vector<uint8_t> > &secureStops) = 0;
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virtual status_t releaseSecureStops(Vector<uint8_t> const &ssRelease) = 0;
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// Read a property value given the device property string. There are a few forms
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// of property access methods, depending on the data type returned.
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// Since DRM plugin properties may vary, additional field names may be defined
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// by each DRM vendor. Refer to your DRM provider documentation for definitions
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// of its additional field names.
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//
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// Standard values are:
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// "vendor" [string] identifies the maker of the plugin
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// "version" [string] identifies the version of the plugin
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// "description" [string] describes the plugin
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// 'deviceUniqueId' [byte array] The device unique identifier is established
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// during device provisioning and provides a means of uniquely identifying
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// each device.
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virtual status_t getPropertyString(String8 const &name, String8 &value ) const = 0;
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virtual status_t getPropertyByteArray(String8 const &name,
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Vector<uint8_t> &value ) const = 0;
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// Write a property value given the device property string. There are a few forms
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// of property setting methods, depending on the data type.
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// Since DRM plugin properties may vary, additional field names may be defined
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// by each DRM vendor. Refer to your DRM provider documentation for definitions
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// of its field names.
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virtual status_t setPropertyString(String8 const &name,
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String8 const &value ) = 0;
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virtual status_t setPropertyByteArray(String8 const &name,
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Vector<uint8_t> const &value ) = 0;
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// The following methods implement operations on a CryptoSession to support
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// encrypt, decrypt, sign verify operations on operator-provided
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// session keys.
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//
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// The algorithm string conforms to JCA Standard Names for Cipher
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// Transforms and is case insensitive. For example "AES/CBC/PKCS5Padding".
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//
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// Return OK if the algorithm is supported, otherwise return BAD_VALUE
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//
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virtual status_t setCipherAlgorithm(Vector<uint8_t> const &sessionId,
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String8 const &algorithm) = 0;
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//
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// The algorithm string conforms to JCA Standard Names for Mac
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// Algorithms and is case insensitive. For example "HmacSHA256".
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//
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// Return OK if the algorithm is supported, otherwise return BAD_VALUE
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//
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virtual status_t setMacAlgorithm(Vector<uint8_t> const &sessionId,
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String8 const &algorithm) = 0;
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// Encrypt the provided input buffer with the cipher algorithm
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// specified by setCipherAlgorithm and the key selected by keyId,
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// and return the encrypted data.
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virtual status_t encrypt(Vector<uint8_t> const &sessionId,
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Vector<uint8_t> const &keyId,
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Vector<uint8_t> const &input,
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Vector<uint8_t> const &iv,
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Vector<uint8_t> &output) = 0;
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// Decrypt the provided input buffer with the cipher algorithm
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// specified by setCipherAlgorithm and the key selected by keyId,
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// and return the decrypted data.
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virtual status_t decrypt(Vector<uint8_t> const &sessionId,
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Vector<uint8_t> const &keyId,
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Vector<uint8_t> const &input,
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Vector<uint8_t> const &iv,
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Vector<uint8_t> &output) = 0;
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// Compute a signature on the provided message using the mac algorithm
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// specified by setMacAlgorithm and the key selected by keyId,
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// and return the signature.
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virtual status_t sign(Vector<uint8_t> const &sessionId,
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Vector<uint8_t> const &keyId,
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Vector<uint8_t> const &message,
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Vector<uint8_t> &signature) = 0;
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// Compute a signature on the provided message using the mac algorithm
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// specified by setMacAlgorithm and the key selected by keyId,
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// and compare with the expected result. Set result to true or
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// false depending on the outcome.
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virtual status_t verify(Vector<uint8_t> const &sessionId,
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Vector<uint8_t> const &keyId,
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Vector<uint8_t> const &message,
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Vector<uint8_t> const &signature,
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bool &match) = 0;
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// TODO: provide way to send an event
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private:
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DISALLOW_EVIL_CONSTRUCTORS(DrmPlugin);
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};
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} // namespace android
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#endif // DRM_API_H_
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