ce_cdm/oemcrypto/util/include/bcc_validator.h

// 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 "cbor_validator.h"
#include "prov4_validation_helper.h"

namespace wvoec {
namespace util {
// Enums and struct to hold EC public key info
enum BccSignatureAlgorithm {
  kBccDefaultSignature = 0,
  kBccEdDsa = 1,
  kBccEcdsaSha256 = 2,
  kBccEcdsaSha384 = 3
};

enum BccCurve {
  kBccDefaultCurve = 0,
  kBccEd25519 = 1,
  kBccP256 = 2,
  kBccP384 = 3
};

// Android/Widevine Dice Attestation allows two signing models. This is
// identified using MAP_KEY_DEVICE_KEY_ALGORITHM.
enum {
  DEVICE_KEY_ALGORITHM_ES256 = -7,   // EC key with SHA-256
  DEVICE_KEY_ALGORITHM_EDDSA = -8,   // Pure ED25519.
  DEVICE_KEY_ALGORITHM_ES384 = -35,  // EC key with SHA-384
};

// BCC definition:
// https://source.corp.google.com/h/googleplex-android/platform/superproject/main/+/main:hardware/interfaces/security/rkp/aidl/android/hardware/security/keymint/generateCertificateRequestV2.cddl

// See PubKeyEd25519/PubKeyECDSA256/PubKeyECDSA384 in BCC definition.
struct BccPublicKeyInfo {
  std::pair<FieldStatus, int> key_type;
  std::pair<FieldStatus, BccSignatureAlgorithm> signature_algorithm;
  std::pair<FieldStatus, BccCurve> curve;
  // Raw EC key bytes extracted from BCC
  std::pair<FieldStatus, std::vector<uint8_t>> key_bytes;
  std::string ToString() const;
  CborMessageStatus Validate(
      std::vector<std::pair<CborMessageStatus, std::string>>& msgs) const;
};

// protected : bstr .cbor { 1 : AlgorithmEdDSA / AlgorithmES256 / AlgorithmES384
// }
struct BccEntryProtected {
  std::pair<FieldStatus, int64_t> algorithm;
  std::string ToString() const;
  CborMessageStatus Validate(
      std::vector<std::pair<CborMessageStatus, std::string>>& msgs) const;
};

// See ConfigurationDescriptor in BCC definition.
struct ConfigurationDescriptor {
  std::pair<FieldStatus, std::string> component_name;
  std::pair<FieldStatus, std::string> component_version;
  std::pair<FieldStatus, std::string> resettable;  // null string
  std::pair<FieldStatus, uint64_t> security_version;
  std::pair<FieldStatus, std::string> vm_marker;  // null string
  std::string ToString() const;
  // Validate ConfigurationDescriptor and set |is_widevine_entry| to true if the
  // component_name is "widevine". Caller ensures that |is_widevine_entry| is
  // not null.
  CborMessageStatus Validate(
      std::vector<std::pair<CborMessageStatus, std::string>>& msgs,
      bool* is_widevine_entry) const;
};

// See DiceChainEntryPayload in BCC definition.
struct BccEntryPayload {
  std::pair<FieldStatus, std::string> issuer;
  std::pair<FieldStatus, std::string> subject;
  std::pair<FieldStatus, std::string> profile_name;
  std::pair<FieldStatus, BccPublicKeyInfo> subject_public_key;
  std::pair<FieldStatus, std::vector<uint8_t>> key_usage;
  std::pair<FieldStatus, std::vector<uint8_t>> code_hash;
  std::pair<FieldStatus, std::vector<uint8_t>> code_descriptor;
  std::pair<FieldStatus, std::vector<uint8_t>> config_hash;
  std::pair<FieldStatus, ConfigurationDescriptor> config_descriptor;
  std::pair<FieldStatus, std::vector<uint8_t>> authority_hash;
  std::pair<FieldStatus, std::vector<uint8_t>> authority_descriptor;
  std::pair<FieldStatus, std::vector<uint8_t>> mode;
  std::string ToString() const;
  // Validate BccEntryPayload and set |is_widevine_entry| to true if the payload
  // contains a Widevine certificate. Caller ensures that |is_widevine_entry| is
  // not null.
  CborMessageStatus Validate(
      std::vector<std::pair<CborMessageStatus, std::string>>& msgs,
      bool is_degenerated, bool* is_widevine_entry) const;
};

// See DiceChainEntry in BCC definition.
struct BccEntry {
  std::pair<FieldStatus, BccEntryProtected> protected_data;
  std::pair<FieldStatus, std::string> unprotected;
  std::pair<FieldStatus, BccEntryPayload> payload;
  std::pair<FieldStatus, std::vector<uint8_t>> signature;
  std::string ToString() const;
  // Validate BccEntryPayload and set |is_widevine_entry| to true if the BCC
  // entry contains a Widevine certificate. Caller ensures that
  // |is_widevine_entry| is not null.
  CborMessageStatus Validate(
      std::vector<std::pair<CborMessageStatus, std::string>>& msgs,
      bool is_degenerated, bool* is_widevine_entry) const;
};

struct Bcc {
  BccPublicKeyInfo dk_pub;
  std::vector<BccEntry> entries;
  std::string ToString() const;
  CborMessageStatus Validate(
      std::vector<std::pair<CborMessageStatus, std::string>>& msgs,
      bool is_degenerated) const;
};

// 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:
  BccValidator() = default;
  virtual ~BccValidator() override = default;
  WVCDM_DISALLOW_COPY_AND_MOVE(BccValidator);

  // Verifies the Cbor struct of a client generated root of trust.
  virtual CborMessageStatus Validate() override;
  // Outputs formatted BCC.
  virtual std::string GetFormattedMessage() const override;

 private:
  // Processes CoseKey PubKeyEd25519 / PubKeyECDSA256 / PubKeyECDSA384, which
  // contains subject public key, and extracts the PubKey to *|public_key_info|.
  // Caller ensures that all pointers are not null.
  CborMessageStatus ProcessSubjectPublicKeyInfo(
      const cppbor::Map* public_key_map, BccPublicKeyInfo* public_key_info);

  // Processes protected field in Bcc entry and extracts it *|protected_data|.
  // Caller ensures that all pointers are not null.
  CborMessageStatus ProcessBccEntryProtected(const cppbor::Map* protected_map,
                                             BccEntryProtected* protected_data);

  // Processes DiceChainEntryPayload and extracts the payload to *|payload|.
  // Caller ensures that all pointers are not null.
  CborMessageStatus ProcessDiceChainEntryPayload(const cppbor::Map* payload_map,
                                                 BccEntryPayload* payload);

  // Processes ConfigurationDescriptor in DiceChainEntryPayload and extracts the
  // ConfigurationDescriptor to *|cd|. Caller ensures that all pointers are not
  // null.
  CborMessageStatus ProcessConfigurationDescriptor(
      const cppbor::Map* config_descriptor_map, ConfigurationDescriptor* cd);

  // Verifies the raw EC signature |signature| with the public key
  // |signing_key|. |signature| extracted from BCC is not ASN.1 DER encoded.
  bool VerifySignature(const BccPublicKeyInfo& signing_key,
                       const std::vector<uint8_t>& message,
                       const std::vector<uint8_t>& signature);
  // Used to generate formatted message.
  std::stringstream msg_ss_;
};  // class BccValidator
}  // namespace util
}  // namespace wvoec
#endif  // WVOEC_UTIL_BCC_VALIDATOR_H_