/**
 * TOTP (Time-based One-Time Password) implementation.
 *
 * Pure Node.js crypto implementation — no external dependencies required.
 * Implements RFC 6238 (TOTP) and RFC 4226 (HOTP).
 */
/**
 * Encode a Buffer to Base32 string (RFC 4648)
 */
export declare function base32Encode(buffer: Buffer): string;
/**
 * Decode a Base32 string to Buffer
 */
export declare function base32Decode(encoded: string): Buffer;
/**
 * Generate a TOTP value for the current time step
 */
export declare function generateTotp(secret: Buffer, timeStep?: number): string;
/**
 * Verify a TOTP token with a configurable time window
 *
 * @param secret - The shared secret as a Buffer
 * @param token - The 6-digit TOTP code to verify
 * @param window - Number of time steps to check on each side (default: 1)
 * @returns true if the token is valid within the window
 */
export declare function verifyTotp(secret: Buffer, token: string, window?: number): boolean;
/**
 * Generate a new TOTP secret and return the setup information
 *
 * @param issuer - The issuer name (app name) for the QR code
 * @param accountName - The account identifier (usually email)
 * @returns Object with base32 secret and otpauth URI
 */
export declare function generateTotpSecret(issuer: string, accountName: string): {
    secret: string;
    uri: string;
};
/**
 * Generate a set of one-time recovery codes
 *
 * @param count - Number of recovery codes to generate (default: 10)
 * @returns Array of formatted recovery code strings (e.g. "A1B2C-D3E4F")
 */
export declare function generateRecoveryCodes(count?: number): string[];
/**
 * Hash a recovery code for storage
 */
export declare function hashRecoveryCode(code: string): string;