Add Bcc validator to oemcrypto util and unit tests

A Bcc validator that can parse and validate BCC. This is to support better
prov40 unit tests regarding OEMCrypto_GetBootCertificateChain() later.

Test: opk_ta_p40
Bug: 300304834
Bug: 307968622
Change-Id: I3cfdad9f1891c6abc83051af1d80a20e0adeb58b

libwvdrmengine/oemcrypto/util/include/bcc_validator.h

@@ -0,0 +1,54 @@
+// Copyright 2023 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+//
+//  Reference implementation utilities of OEMCrypto APIs
+//
+#ifndef WVOEC_UTIL_BCC_VALIDATOR_H_
+#define WVOEC_UTIL_BCC_VALIDATOR_H_
+
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include "cbor_validator.h"
+#include "cppbor.h"
+
+namespace wvoec {
+namespace util {
+// BccValidator processes a Provisioning 4.0 device root of trust. It extracts
+// and validates relevant pieces of information of BCC.
+// Relevant documents:
+// Android definition: go/remote-provisioning-hal#bcc.
+// Google Dice Profile: go/dice-profile
+class BccValidator : public CborValidator {
+ public:
+  explicit BccValidator() {}
+  virtual ~BccValidator() override = default;
+  BccValidator(const BccValidator&) = delete;
+  BccValidator& operator=(const BccValidator&) = delete;
+  // Verifies the Cbor struct of a client generated root of trust. This message
+  // is part of an attestation model conforming to the Google Open Dice Profile.
+  // This message is received from a client device to attest it is a valid
+  // Widevine device.
+  virtual CborMessageStatus Validate() override;
+  // Outputs BCC in YAML.
+  virtual std::string GetFormattedMessage() const override;
+
+ private:
+  // Processes CoseKey PubKeyEd25519 / PubKeyECDSA256, prints into |fmt_msgs|,
+  // and extracts the PubKey string to *|public_key_bytes|.
+  CborMessageStatus ProcessSubjectPublicKeyInfo(
+      const cppbor::Map& public_key_info_map,
+      std::vector<std::string>& fmt_msgs, std::string* public_key_bytes);
+  // Processes DiceChainEntryPayload, which contains subject public key, prints
+  // into |fmt_msgs|, and extracts the PubKey string to *|public_key_bytes|.
+  CborMessageStatus ProcessDiceChainEntryPayload(
+      const std::vector<uint8_t>& payload, std::vector<std::string>& fmt_msgs,
+      std::string* public_key_bytes);
+  // Used to generate formatted message.
+  std::stringstream msg_ss_;
+};
+}  // namespace util
+}  // namespace wvoec
+#endif  // WVOEC_UTIL_BCC_VALIDATOR_H_