cryptohome/signature_sealed_data.proto

// Copyright 2018 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;

// Container for the signature-sealed data, including the additional non-secret
// information required for unsealing.
message SignatureSealedData {
  // Index and value of a TPM Platform Configuration Register (PCR).
  message PcrValue {
    optional uint32 pcr_index = 1;
    optional bytes pcr_value = 2;
  }

  // Information about a single set of PCR restrictions for TPM 2.0.
  message Tpm2PcrRestriction {
    // List of PCR values that must be all satisfied for this restriction.
    repeated PcrValue pcr_values = 1;

    // TPM policy digest for the TPM2_PolicyPCR command executed with the PCR
    // values specified by |pcr_values|.
    optional bytes policy_digest = 2;
  }

  // Data for the TPM 2.0 method based on the "TPM2_PolicySigned" feature.
  message Tpm2PolicySignedData {
    // DER-encoded blob of the X.509 Subject Public Key Info of the key that
    // should be used for unsealing.
    optional bytes public_key_spki_der = 1;

    // The secret blob, wrapped by the TPM's Storage Root Key.
    optional bytes srk_wrapped_secret = 2;

    // The signature scheme (TPM_ALG_ID) that should be used for unsealing.
    optional int32 scheme = 3;

    // The signature hash algorithm (TPM_ALG_ID) that should be used for
    // unsealing.
    optional int32 hash_alg = 4;

    // Multiple alternative sets of PCR restrictions that are applied to the
    // wrapped secret. For unsealing, it's enough to satisfy only one of those
    // restrictions.
    // Note that the order of items here is important: it defines the order of
    // arguments when building the TPM policy digest.
    repeated Tpm2PcrRestriction pcr_restrictions = 5;
  }

  // TPM 1.2 data that is bound to the specific set of PCRs.
  message Tpm12PcrBoundItem {
    // Set of PCRs to which the secret blob is bound.
    repeated PcrValue pcr_values = 1;

    // The secret blob, which is bound to the PCR values specified by
    // |pcr_values| and with the AuthData value that is stored encrypted in
    // |cmk_wrapped_auth_data|.
    optional bytes bound_secret = 2;
  }

  // Data for the TPM 1.2 method based on the "Certified Migratable Key"
  // functionality.
  message Tpm12CertifiedMigratableKeyData {
    // DER-encoded blob of the X.509 Subject Public Key Info of the key that
    // should be used for unsealing.
    optional bytes public_key_spki_der = 1;

    // The blob of the Certified Migratable Key wrapped by the TPM's Storage
    // Root Key.
    optional bytes srk_wrapped_cmk = 2;

    // The TPM_PUBKEY blob of the Certified Migratable Key.
    optional bytes cmk_pubkey = 3;

    // The AuthData blob encrypted by the CMK using the RSAES-OAEP MGF1
    // algorithm.
    optional bytes cmk_wrapped_auth_data = 4;

    // Multiple alternative representations of the secret data, where each
    // representation is bound to its specific set of PCRs and to the AuthData
    // value that is stored encrypted in |cmk_wrapped_auth_data|.
    repeated Tpm12PcrBoundItem pcr_bound_items = 5;
  }

  // The union containing the data depending on the sealing method.
  oneof data {
    Tpm2PolicySignedData tpm2_policy_signed_data = 1;
    Tpm12CertifiedMigratableKeyData tpm12_certified_migratable_key_data = 2;
  }
}