Remove unused KeyChainSnapshot tables

        static final String COLUMN_NAME_RECOVERY_STATUS = "recovery_status";

    }

    /**

     * Table holding encrypted snapshots of the recoverable key store.

     */

    static class SnapshotsEntry implements BaseColumns {

        static final String TABLE_NAME = "snapshots";

        /**

         * The version number of the snapshot.

         */

        static final String COLUMN_NAME_VERSION = "version";

        /**

         * The ID of the user whose keystore was snapshotted.

         */

        static final String COLUMN_NAME_USER_ID = "user_id";

        /**

         * The UID of the app that owns the snapshot (i.e., the recovery agent).

         */

        static final String COLUMN_NAME_UID = "uid";

        /**

         * The maximum number of attempts allowed to attempt to decrypt the recovery key.

         */

        static final String COLUMN_NAME_MAX_ATTEMPTS = "max_attempts";

        /**

         * The ID of the counter in the trusted hardware module.

         */

        static final String COLUMN_NAME_COUNTER_ID = "counter_id";

        /**

         * Server parameters used to help identify the device (during recovery).

         */

        static final String SERVER_PARAMS = "server_params";

        /**

         * The public key of the trusted hardware module. This key has been used to encrypt the

         * snapshot, to ensure that it can only be read by the trusted module.

         */

        static final String TRUSTED_HARDWARE_PUBLIC_KEY = "thm_public_key";

        /**

         * {@link java.security.cert.CertPath} signing the trusted hardware module to whose public

         * key this snapshot is encrypted.

         */

        static final String CERT_PATH = "cert_path";

        /**

         * The recovery key, encrypted with the user's lock screen and the trusted hardware module's

         * public key.

         */

        static final String ENCRYPTED_RECOVERY_KEY = "encrypted_recovery_key";

    }

    /**

     * Table holding encrypted keys belonging to a particular snapshot.

     */

    static class SnapshotKeysEntry implements BaseColumns {

        static final String TABLE_NAME = "snapshot_keys";

        /**

         * ID of the associated snapshot entry in {@link SnapshotsEntry}.

         */

        static final String COLUMN_NAME_SNAPSHOT_ID = "snapshot_id";

        /**

         * Alias of the key.

         */

        static final String COLUMN_NAME_ALIAS = "alias";

        /**

         * Key material, encrypted with the recovery key from the snapshot.

         */

        static final String COLUMN_NAME_ENCRYPTED_BYTES = "encrypted_key_bytes";

    }

    /**

     * A layer of protection associated with a snapshot.

     */

    static class SnapshotProtectionParams implements BaseColumns {

        static final String TABLE_NAME = "snapshot_protection_params";

        /**

         * ID of the associated snapshot entry in {@link SnapshotsEntry}.

         */

        static final String COLUMN_NAME_SNAPSHOT_ID = "snapshot_id";

        /**

         * Type of secret used to generate recovery key. One of

         * {@link android.security.keystore.recovery.KeyChainProtectionParams#TYPE_LOCKSCREEN} or

         */

        static final String COLUMN_NAME_SECRET_TYPE = "secret_type";

        /**

         * If a lock screen, the type of UI used. One of

         * {@link android.security.keystore.recovery.KeyChainProtectionParams#UI_FORMAT_PATTERN},

         * {@link android.security.keystore.recovery.KeyChainProtectionParams#UI_FORMAT_PIN}, or

         * {@link android.security.keystore.recovery.KeyChainProtectionParams#UI_FORMAT_PASSWORD}.

         */

        static final String COLUMN_NAME_LOCKSCREEN_UI_TYPE = "lock_screen_ui_type";

        /**

         * The algorithm used to derive cryptographic material from the key and salt. One of

         * {@link android.security.keystore.recovery.KeyDerivationParams#ALGORITHM_SHA256} or

         * {@link android.security.keystore.recovery.KeyDerivationParams#ALGORITHM_SCRYPT}.

         */

        static final String COLUMN_NAME_KEY_DERIVATION_ALGORITHM = "key_derivation_algorithm";

        /**

         * The salt used along with the secret to generate cryptographic material.

         */

        static final String COLUMN_NAME_KEY_DERIVATION_SALT = "key_derivation_salt";

    }

    /**

     * Recoverable KeyStore metadata for a specific user profile.

     */