cryptohome/auth_block_state.proto

// Copyright 2021 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

syntax = "proto2";

package cryptohome;

// These fields are all marked optional because these protobufs are generated
// from objects stored on disk, such as the SerializedVaultKeyset. As a result
// cryptohome cannot assume the protobuf is always as expected. However, the
// fields should always be defined or the auth block cannot operate.
message AuthBlockState {
  message TpmNotBoundToPcrAuthBlockState {
    // Marks if the password is run through scrypt before going to the TPM.
    optional bool scrypt_derived = 1;
    // The salt used to bind to the TPM.
    optional bytes salt = 2;
    // The number of rounds key derivation is called.
    optional uint32 password_rounds = 3;
    // The VKK wrapped with the user's password by the tpm.
    optional bytes tpm_key = 4;
    // A check if this is the same TPM that wrapped the credential.
    optional bytes tpm_public_key_hash = 5;
    // The wrapped reset seed to reset LE credentials.
    optional bytes wrapped_reset_seed = 6;
  }
  message TpmBoundToPcrAuthBlockState {
    // Marks if the password is run through scrypt before going to the TPM.
    optional bool scrypt_derived = 1;
    // The salt used to bind to the TPM.
    optional bytes salt = 2;
    // The VKK encrypted with the user's password and TPM.
    optional bytes tpm_key = 3;
    // Same as tpm_key, but extends the PCR to only allow one user until reboot.
    optional bytes extended_tpm_key = 4;
    // A check if this is the same TPM that wrapped the credential.
    optional bytes tpm_public_key_hash = 5;
    // The wrapped reset seed to reset LE credentials.
    optional bytes wrapped_reset_seed = 6;
  }
  message PinWeaverAuthBlockState {
    // The label for the credential in the LE hash tree.
    optional uint64 le_label = 1;
    // The salt used to first scrypt the user input.
    optional bytes salt = 2;
    // The IV used to derive the chaps key.
    optional bytes chaps_iv = 3;
    // The IV used to derive the file encryption key.
    optional bytes fek_iv = 4;
  }
  // This is a unique AuthBlockState for backwards compatibility. libscrypt puts
  // the metadata, such as IV and salt, into the header of the encrypted
  // buffer. Thus this is the only auth block state to pass wrapped secrets. See
  // the LibScryptCompatAuthBlock header for a full explanation.
  message LibScryptCompatAuthBlockState {
    // The wrapped filesystem keys.
    optional bytes wrapped_keyset = 1;
    // The wrapped chaps keys.
    optional bytes wrapped_chaps_key = 2;
    // The wrapped reset seed keys.
    optional bytes wrapped_reset_seed = 3;
  }
  message ChallengeCredentialAuthBlockState {
    required LibScryptCompatAuthBlockState scrypt_state = 1;
  }
  message DoubleWrappedCompatAuthBlockState {
    required LibScryptCompatAuthBlockState scrypt_state = 1;
    required TpmNotBoundToPcrAuthBlockState tpm_state = 2;
  }
  message CryptohomeRecoveryAuthBlockState {
    // Contains encrypted mediator share and data required for decryption.
    message EncryptedMediatorShare {
      // The integrity tag of the data generated during encryption of the
      // mediator share.
      optional bytes tag = 1;
      // The initialization vector generated during encryption of the mediator
      // share.
      optional bytes iv = 2;
      // Ephemeral key created during encryption of the mediator share.
      optional bytes ephemeral_pub_key = 3;
      // Encrypted mediator share.
      optional bytes encrypted_data = 4;
    };
    // Secret share of the mediator encrypted to the mediator public key.
    optional EncryptedMediatorShare encrypted_mediator_share = 1;
    // Secret share of the destination (plaintext).
    // TODO(b/184924482): store encrypted destination share.
    optional bytes plaintext_destination_share = 2;
    // The public key of the publisher ECC key.
    optional bytes publisher_pub_key = 3;
  }

  oneof auth_block_state {
    TpmNotBoundToPcrAuthBlockState tpm_not_bound_to_pcr_state = 1;
    TpmBoundToPcrAuthBlockState tpm_bound_to_pcr_state = 2;
    PinWeaverAuthBlockState pin_weaver_state = 3;
    LibScryptCompatAuthBlockState libscrypt_compat_state = 4;
    ChallengeCredentialAuthBlockState challenge_credential_state = 5;
    DoubleWrappedCompatAuthBlockState double_wrapped_compat_state = 6;
    CryptohomeRecoveryAuthBlockState cryptohome_recovery_state = 7;
  }
}