/**
 * Copyright 2020 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { JsonObject } from './common';
import { OAuth2Client } from 'google-auth-library';
/**
 * This class provides methods to process the auth header to streamline access to auth credentials.
 *
 * @hidden
 */
export declare class AuthHeaderProcessor {
    /**
     * Used to verify and decode GSI tokens.
     */
    authClient: OAuth2Client;
    /**
     * Used to extract the token value from headers that contain a bearer token.
     */
    static readonly bearerTypeTag = "Bearer ";
    constructor();
    /**
     * Validates a GSI token using the provided client ID and returns the GSI token payload as
     * a json object.
     * @param gsiToken The GSI token to validate and decode.
     * @param clientId The Client ID to use for validation.
     * @returns The decoded token payload.
     */
    decodeGSIToken(gsiToken: string, clientId: string): Promise<JsonObject>;
    /**
     * Extracts the token value from a bearer token, stripping the type tag 'Bearer '.
     *
     * @param authHeader The auth header to parse.
     * @returns The value of the token, or a null string if authHeader doesn't contain a bearer token.
     */
    extractAccessToken(authHeader: string): string;
}