/**
 * Generates a cryptographically random PKCE code verifier.
 *
 * @returns A 128-character base64url-encoded random string
 */
export declare function generateCodeVerifier(): string;
/**
 * Generates a PKCE code challenge from a code verifier using S256.
 *
 * @param verifier - The code verifier to hash
 * @returns The base64url-encoded SHA-256 hash of the verifier
 */
export declare function generateCodeChallenge(verifier: string): string;