export declare class OAuthUtils {
    static readonly charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~";
    static generateRandomString(length?: number): string;
    static generateCodeVerifier(length?: number): string;
    static generateState(): string;
    static verifyState(storedState: string, receivedState: string): boolean;
    static generateCodeChallenge(verifier: string): Promise<string>;
    static bufferToBase64url(buffer: ArrayBuffer): string;
}