60 lines
2.2 KiB
C++
60 lines
2.2 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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// Copyright 2019 Google LLC.
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//
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// This software is licensed under the terms defined in the Widevine Master
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// License Agreement. For a copy of this agreement, please contact
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// widevine-licensing@google.com.
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////////////////////////////////////////////////////////////////////////////////
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//
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// Description:
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// Helper methods for the Root of Trust Id.
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#ifndef COMMON_ROT_ID_UTIL_H_
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#define COMMON_ROT_ID_UTIL_H_
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#include <memory>
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#include <vector>
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#include <cstdint>
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#include "common/ec_key.h"
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#include "common/local_ec_key_source.h"
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namespace widevine {
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// Helper function that generates the hash for the ROT id from the
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// |unique_id_hash|, the |system_id| and the |salt|. |salt| is typically an
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// encrypted unique id. Since we use an ephemeral eliptic curve key as part of
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// the encrypted unique id, the value is effectively random can be used as a
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// salt.
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// Returns the hash value on success.
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// If |salt| or |unique_id_hash| are empty, this will return an empty
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// string.
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std::string GenerateRotIdHash(const std::string& salt, uint32_t system_id,
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const std::string& unique_id_hash);
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// Helper function that compares the |rot_id_hash| to a hash of each of the
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// |revoked_ids|. The |revoked_ids| are the unique id hash (aka inner hash)
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// values as defined in the spec at go/wv-kb-id. The |encrypted_unique_id| and
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// |system_id| are used to compute the hash of each of the |revoked_ids|.
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// Returns true if any of the revoked_ids match.
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template <typename V>
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bool IsRotIdRevoked(const std::string& encrypted_unique_id, uint32_t system_id,
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const std::string& rot_id_hash, const V& revoked_ids) {
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// This could conceivably happen for legacy DRM certificates without a ROT id.
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// No need to match if there's nothing to match against.
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if (encrypted_unique_id.empty() || rot_id_hash.empty()) {
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return false;
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}
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for (const auto& revoked_id : revoked_ids) {
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if (GenerateRotIdHash(encrypted_unique_id, system_id, revoked_id) ==
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rot_id_hash) {
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return true;
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}
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}
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return false;
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}
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} // namespace widevine
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#endif // COMMON_ROT_ID_UTIL_H_
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