drm/mediadrm/plugins/clearkey/hidl/JsonWebKey.cpp - third_party/android/platform/frameworks/av - Git at Google

 /*
  * Copyright (C) 2018 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 #define LOG_TAG "hidl_JsonWebKey"

 #include <utils/Log.h>

 #include "JsonWebKey.h"

 #include "Base64.h"

 namespace {
 const std::string kBase64Padding("=");
 const std::string kKeysTag("keys");
 const std::string kKeyTypeTag("kty");
 const std::string kKeyTag("k");
 const std::string kKeyIdTag("kid");
 const std::string kMediaSessionType("type");
 const std::string kPersistentLicenseSession("persistent-license");
 const std::string kSymmetricKeyValue("oct");
 const std::string kTemporaryLicenseSession("temporary");
 }

 namespace android {
 namespace hardware {
 namespace drm {
 namespace V1_2 {
 namespace clearkey {

 JsonWebKey::JsonWebKey() {
 }

 JsonWebKey::~JsonWebKey() {
 }

 /*
  * Parses a JSON Web Key Set string, initializes a KeyMap with key id:key
  * pairs from the JSON Web Key Set. Both key ids and keys are base64url
  * encoded. The KeyMap contains base64url decoded key id:key pairs.
  *
  * @return Returns false for errors, true for success.
  */
 bool JsonWebKey::extractKeysFromJsonWebKeySet(const std::string& jsonWebKeySet,
         KeyMap* keys) {

     keys->clear();

     if (!parseJsonWebKeySet(jsonWebKeySet, &mJsonObjects)) {
         return false;
     }

     // mJsonObjects[0] contains the entire JSON Web Key Set, including
     // all the base64 encoded keys. Each key is also stored separately as
     // a JSON object in mJsonObjects[1..n] where n is the total
     // number of keys in the set.
     if (!isJsonWebKeySet(mJsonObjects[0])) {
         return false;
     }

     std::string encodedKey, encodedKeyId;
     std::vector<uint8_t> decodedKey, decodedKeyId;

     // mJsonObjects[1] contains the first JSON Web Key in the set
     for (size_t i = 1; i < mJsonObjects.size(); ++i) {
         encodedKeyId.clear();
         encodedKey.clear();

         if (!parseJsonObject(mJsonObjects[i], &mTokens))
             return false;

         if (findKey(mJsonObjects[i], &encodedKeyId, &encodedKey)) {
             if (encodedKeyId.empty() || encodedKey.empty()) {
                 ALOGE("Must have both key id and key in the JsonWebKey set.");
                 continue;
             }

             if (!decodeBase64String(encodedKeyId, &decodedKeyId)) {
                 ALOGE("Failed to decode key id(%s)", encodedKeyId.c_str());
                 continue;
             }

             if (!decodeBase64String(encodedKey, &decodedKey)) {
                 ALOGE("Failed to decode key(%s)", encodedKey.c_str());
                 continue;
             }

             keys->insert(std::pair<std::vector<uint8_t>,
                     std::vector<uint8_t> >(decodedKeyId, decodedKey));
         }
     }
     return true;
 }

 bool JsonWebKey::decodeBase64String(const std::string& encodedText,
         std::vector<uint8_t>* decodedText) {

     decodedText->clear();

     // encodedText should not contain padding characters as per EME spec.
     if (encodedText.find(kBase64Padding) != std::string::npos) {
         return false;
     }

     // Since decodeBase64() requires padding characters,
     // add them so length of encodedText is exactly a multiple of 4.
     int remainder = encodedText.length() % 4;
     std::string paddedText(encodedText);
     if (remainder > 0) {
         for (int i = 0; i < 4 - remainder; ++i) {
             paddedText.append(kBase64Padding);
         }
     }

     sp<Buffer> buffer = decodeBase64(paddedText);
     if (buffer == nullptr) {
         ALOGE("Malformed base64 encoded content found.");
         return false;
     }

     decodedText->insert(decodedText->end(), buffer->base(), buffer->base() + buffer->size());
     return true;
 }

 bool JsonWebKey::findKey(const std::string& jsonObject, std::string* keyId,
         std::string* encodedKey) {

     std::string key, value;

     // Only allow symmetric key, i.e. "kty":"oct" pair.
     if (jsonObject.find(kKeyTypeTag) != std::string::npos) {
         findValue(kKeyTypeTag, &value);
         if (0 != value.compare(kSymmetricKeyValue))
             return false;
     }

     if (jsonObject.find(kKeyIdTag) != std::string::npos) {
         findValue(kKeyIdTag, keyId);
     }

     if (jsonObject.find(kKeyTag) != std::string::npos) {
         findValue(kKeyTag, encodedKey);
     }
     return true;
 }

 void JsonWebKey::findValue(const std::string &key, std::string* value) {
     value->clear();
     const char* valueToken;
     for (std::vector<std::string>::const_iterator nextToken = mTokens.begin();
         nextToken != mTokens.end(); ++nextToken) {
         if (0 == (*nextToken).compare(key)) {
             if (nextToken + 1 == mTokens.end())
                 break;
             valueToken = (*(nextToken + 1)).c_str();
             value->assign(valueToken);
             nextToken++;
             break;
         }
     }
 }

 bool JsonWebKey::isJsonWebKeySet(const std::string& jsonObject) const {
     if (jsonObject.find(kKeysTag) == std::string::npos) {
         ALOGE("JSON Web Key does not contain keys.");
         return false;
     }
     return true;
 }

 /*
  * Parses a JSON objects string and initializes a vector of tokens.
  *
  * @return Returns false for errors, true for success.
  */
 bool JsonWebKey::parseJsonObject(const std::string& jsonObject,
         std::vector<std::string>* tokens) {
     jsmn_parser parser;

     jsmn_init(&parser);
     int numTokens = jsmn_parse(&parser,
         jsonObject.c_str(), jsonObject.size(), nullptr, 0);
     if (numTokens < 0) {
         ALOGE("Parser returns error code=%d", numTokens);
         return false;
     }

     unsigned int jsmnTokensSize = numTokens * sizeof(jsmntok_t);
     mJsmnTokens.clear();
     mJsmnTokens.resize(jsmnTokensSize);

     jsmn_init(&parser);
     int status = jsmn_parse(&parser, jsonObject.c_str(),
         jsonObject.size(), mJsmnTokens.data(), numTokens);
     if (status < 0) {
         ALOGE("Parser returns error code=%d", status);
         return false;
     }

     tokens->clear();
     std::string token;
     const char *pjs;
     for (int j = 0; j < numTokens; ++j) {
         pjs = jsonObject.c_str() + mJsmnTokens[j].start;
         if (mJsmnTokens[j].type == JSMN_STRING ||
                 mJsmnTokens[j].type == JSMN_PRIMITIVE) {
             token.assign(pjs, mJsmnTokens[j].end - mJsmnTokens[j].start);
             tokens->push_back(token);
         }
     }
     return true;
 }

 /*
  * Parses JSON Web Key Set string and initializes a vector of JSON objects.
  *
  * @return Returns false for errors, true for success.
  */
 bool JsonWebKey::parseJsonWebKeySet(const std::string& jsonWebKeySet,
         std::vector<std::string>* jsonObjects) {
     if (jsonWebKeySet.empty()) {
         ALOGE("Empty JSON Web Key");
         return false;
     }

     // The jsmn parser only supports unicode encoding.
     jsmn_parser parser;

     // Computes number of tokens. A token marks the type, offset in
     // the original string.
     jsmn_init(&parser);
     int numTokens = jsmn_parse(&parser,
             jsonWebKeySet.c_str(), jsonWebKeySet.size(), nullptr, 0);
     if (numTokens < 0) {
         ALOGE("Parser returns error code=%d", numTokens);
         return false;
     }

     unsigned int jsmnTokensSize = numTokens * sizeof(jsmntok_t);
     mJsmnTokens.resize(jsmnTokensSize);

     jsmn_init(&parser);
     int status = jsmn_parse(&parser, jsonWebKeySet.c_str(),
             jsonWebKeySet.size(), mJsmnTokens.data(), numTokens);
     if (status < 0) {
         ALOGE("Parser returns error code=%d", status);
         return false;
     }

     std::string token;
     const char *pjs;
     for (int i = 0; i < numTokens; ++i) {
         pjs = jsonWebKeySet.c_str() + mJsmnTokens[i].start;
         if (mJsmnTokens[i].type == JSMN_OBJECT) {
             token.assign(pjs, mJsmnTokens[i].end - mJsmnTokens[i].start);
             jsonObjects->push_back(token);
         }
     }
     return true;
 }

 } // namespace clearkey
 } // namespace V1_2
 } // namespace drm
 } // namespace hardware
 } // namespace android
	/*
	* Copyright (C) 2018 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	#define LOG_TAG "hidl_JsonWebKey"

	#include <utils/Log.h>

	#include "JsonWebKey.h"

	#include "Base64.h"

	namespace {
	const std::string kBase64Padding("=");
	const std::string kKeysTag("keys");
	const std::string kKeyTypeTag("kty");
	const std::string kKeyTag("k");
	const std::string kKeyIdTag("kid");
	const std::string kMediaSessionType("type");
	const std::string kPersistentLicenseSession("persistent-license");
	const std::string kSymmetricKeyValue("oct");
	const std::string kTemporaryLicenseSession("temporary");
	}

	namespace android {
	namespace hardware {
	namespace drm {
	namespace V1_2 {
	namespace clearkey {

	JsonWebKey::JsonWebKey() {
	}

	JsonWebKey::~JsonWebKey() {
	}

	/*
	* Parses a JSON Web Key Set string, initializes a KeyMap with key id:key
	* pairs from the JSON Web Key Set. Both key ids and keys are base64url
	* encoded. The KeyMap contains base64url decoded key id:key pairs.
	*
	* @return Returns false for errors, true for success.
	*/
	bool JsonWebKey::extractKeysFromJsonWebKeySet(const std::string& jsonWebKeySet,
	KeyMap* keys) {

	keys->clear();

	if (!parseJsonWebKeySet(jsonWebKeySet, &mJsonObjects)) {
	return false;
	}

	// mJsonObjects[0] contains the entire JSON Web Key Set, including
	// all the base64 encoded keys. Each key is also stored separately as
	// a JSON object in mJsonObjects[1..n] where n is the total
	// number of keys in the set.
	if (!isJsonWebKeySet(mJsonObjects[0])) {
	return false;
	}

	std::string encodedKey, encodedKeyId;
	std::vector<uint8_t> decodedKey, decodedKeyId;

	// mJsonObjects[1] contains the first JSON Web Key in the set
	for (size_t i = 1; i < mJsonObjects.size(); ++i) {
	encodedKeyId.clear();
	encodedKey.clear();

	if (!parseJsonObject(mJsonObjects[i], &mTokens))
	return false;

	if (findKey(mJsonObjects[i], &encodedKeyId, &encodedKey)) {
	if (encodedKeyId.empty() \|\| encodedKey.empty()) {
	ALOGE("Must have both key id and key in the JsonWebKey set.");
	continue;
	}

	if (!decodeBase64String(encodedKeyId, &decodedKeyId)) {
	ALOGE("Failed to decode key id(%s)", encodedKeyId.c_str());
	continue;
	}

	if (!decodeBase64String(encodedKey, &decodedKey)) {
	ALOGE("Failed to decode key(%s)", encodedKey.c_str());
	continue;
	}

	keys->insert(std::pair<std::vector<uint8_t>,
	std::vector<uint8_t> >(decodedKeyId, decodedKey));
	}
	}
	return true;
	}

	bool JsonWebKey::decodeBase64String(const std::string& encodedText,
	std::vector<uint8_t>* decodedText) {

	decodedText->clear();

	// encodedText should not contain padding characters as per EME spec.
	if (encodedText.find(kBase64Padding) != std::string::npos) {
	return false;
	}

	// Since decodeBase64() requires padding characters,
	// add them so length of encodedText is exactly a multiple of 4.
	int remainder = encodedText.length() % 4;
	std::string paddedText(encodedText);
	if (remainder > 0) {
	for (int i = 0; i < 4 - remainder; ++i) {
	paddedText.append(kBase64Padding);
	}
	}

	sp<Buffer> buffer = decodeBase64(paddedText);
	if (buffer == nullptr) {
	ALOGE("Malformed base64 encoded content found.");
	return false;
	}

	decodedText->insert(decodedText->end(), buffer->base(), buffer->base() + buffer->size());
	return true;
	}

	bool JsonWebKey::findKey(const std::string& jsonObject, std::string* keyId,
	std::string* encodedKey) {

	std::string key, value;

	// Only allow symmetric key, i.e. "kty":"oct" pair.
	if (jsonObject.find(kKeyTypeTag) != std::string::npos) {
	findValue(kKeyTypeTag, &value);
	if (0 != value.compare(kSymmetricKeyValue))
	return false;
	}

	if (jsonObject.find(kKeyIdTag) != std::string::npos) {
	findValue(kKeyIdTag, keyId);
	}

	if (jsonObject.find(kKeyTag) != std::string::npos) {
	findValue(kKeyTag, encodedKey);
	}
	return true;
	}

	void JsonWebKey::findValue(const std::string &key, std::string* value) {
	value->clear();
	const char* valueToken;
	for (std::vector<std::string>::const_iterator nextToken = mTokens.begin();
	nextToken != mTokens.end(); ++nextToken) {
	if (0 == (*nextToken).compare(key)) {
	if (nextToken + 1 == mTokens.end())
	break;
	valueToken = (*(nextToken + 1)).c_str();
	value->assign(valueToken);
	nextToken++;
	break;
	}
	}
	}

	bool JsonWebKey::isJsonWebKeySet(const std::string& jsonObject) const {
	if (jsonObject.find(kKeysTag) == std::string::npos) {
	ALOGE("JSON Web Key does not contain keys.");
	return false;
	}
	return true;
	}

	/*
	* Parses a JSON objects string and initializes a vector of tokens.
	*
	* @return Returns false for errors, true for success.
	*/
	bool JsonWebKey::parseJsonObject(const std::string& jsonObject,
	std::vector<std::string>* tokens) {
	jsmn_parser parser;

	jsmn_init(&parser);
	int numTokens = jsmn_parse(&parser,
	jsonObject.c_str(), jsonObject.size(), nullptr, 0);
	if (numTokens < 0) {
	ALOGE("Parser returns error code=%d", numTokens);
	return false;
	}

	unsigned int jsmnTokensSize = numTokens * sizeof(jsmntok_t);
	mJsmnTokens.clear();
	mJsmnTokens.resize(jsmnTokensSize);

	jsmn_init(&parser);
	int status = jsmn_parse(&parser, jsonObject.c_str(),
	jsonObject.size(), mJsmnTokens.data(), numTokens);
	if (status < 0) {
	ALOGE("Parser returns error code=%d", status);
	return false;
	}

	tokens->clear();
	std::string token;
	const char *pjs;
	for (int j = 0; j < numTokens; ++j) {
	pjs = jsonObject.c_str() + mJsmnTokens[j].start;
	if (mJsmnTokens[j].type == JSMN_STRING \|\|
	mJsmnTokens[j].type == JSMN_PRIMITIVE) {
	token.assign(pjs, mJsmnTokens[j].end - mJsmnTokens[j].start);
	tokens->push_back(token);
	}
	}
	return true;
	}

	/*
	* Parses JSON Web Key Set string and initializes a vector of JSON objects.
	*
	* @return Returns false for errors, true for success.
	*/
	bool JsonWebKey::parseJsonWebKeySet(const std::string& jsonWebKeySet,
	std::vector<std::string>* jsonObjects) {
	if (jsonWebKeySet.empty()) {
	ALOGE("Empty JSON Web Key");
	return false;
	}

	// The jsmn parser only supports unicode encoding.
	jsmn_parser parser;

	// Computes number of tokens. A token marks the type, offset in
	// the original string.
	jsmn_init(&parser);
	int numTokens = jsmn_parse(&parser,
	jsonWebKeySet.c_str(), jsonWebKeySet.size(), nullptr, 0);
	if (numTokens < 0) {
	ALOGE("Parser returns error code=%d", numTokens);
	return false;
	}

	unsigned int jsmnTokensSize = numTokens * sizeof(jsmntok_t);
	mJsmnTokens.resize(jsmnTokensSize);

	jsmn_init(&parser);
	int status = jsmn_parse(&parser, jsonWebKeySet.c_str(),
	jsonWebKeySet.size(), mJsmnTokens.data(), numTokens);
	if (status < 0) {
	ALOGE("Parser returns error code=%d", status);
	return false;
	}

	std::string token;
	const char *pjs;
	for (int i = 0; i < numTokens; ++i) {
	pjs = jsonWebKeySet.c_str() + mJsmnTokens[i].start;
	if (mJsmnTokens[i].type == JSMN_OBJECT) {
	token.assign(pjs, mJsmnTokens[i].end - mJsmnTokens[i].start);
	jsonObjects->push_back(token);
	}
	}
	return true;
	}

	} // namespace clearkey
	} // namespace V1_2
	} // namespace drm
	} // namespace hardware
	} // namespace android