/**
 * Type representing a Firebase OAuth access token (derived from a Google OAuth2 access token) which
 * can be used to authenticate to Firebase services such as the Realtime Database and Auth.
 */
export interface FirebaseAccessToken {
    accessToken: string;
    expirationTime: number;
}
/**
 * Interface for Google OAuth 2.0 access tokens.
 */
export interface GoogleOAuthAccessToken {
    access_token: string;
    expires_in: number;
}
/**
 * Interface that provides Google OAuth2 access tokens used to authenticate
 * with Firebase services.
 *
 * In most cases, you will not need to implement this yourself and can instead
 * use the default implementations provided by the `firebase-admin/app` module.
 */
export interface Credential {
    /**
     * Returns a Google OAuth2 access token object used to authenticate with
     * Firebase services.
     *
     * @returns A Google OAuth2 access token object.
     */
    getAccessToken(): Promise<GoogleOAuthAccessToken>;
}
/**
 * Implementation of Credential that uses a service account.
 */
export declare class ServiceAccountCredential implements Credential {
    readonly projectId: string;
    readonly privateKey: string;
    readonly clientEmail: string;
    /**
     * Creates a new ServiceAccountCredential from the given parameters.
     *
     * @param serviceAccountJson - Service account json content.
     *
     * @constructor
     */
    constructor(serviceAccountJson: string);
    getAccessToken(): Promise<GoogleOAuthAccessToken>;
    private sign;
    private str2ab;
}