native-browser-otp/dist/otp.d.ts

Lightweight library for generating TOTP and HOTP codes using browser's native Web Cryptography API. Perfect for implementing two-factor authentication (2FA) in web applications.

/**
 * The HOTP algorithm is based on an increasing counter value (C) and a
 * static symmetric key known only to the token and the validation
 * service (K). In order to create the HOTP value.
 *
 *  We can describe the operations in 3 distinct steps:
 *
 *  Step 1: Generate an HMAC-SHA-1 value Let HS = HMAC-SHA-1(K,C)  // HS
 *  is a 20-byte string
 *
 *  Step 2: Generate a 4-byte string (Dynamic Truncation) (see truncate() above)
 *
 *  Step 3: Compute an HOTP value
 *  Let Snum  = StToNum(Sbits)   // Convert S to a number in
 *                                   0...2^{31}-1
 *  Return D = Snum mod 10^Digit //  D is a number in the range
 *                                   0...10^{Digit}-1
 *
 * See: https://datatracker.ietf.org/doc/html/rfc4226
 *
 * @param secret - static symmetric key known only to the token and the validation
 * service
 * @param counter - an increasing counter value
 * @returns OTP
 */
export declare function hotp(secret: string, counter: number): Promise<string>;
/**
 * TOTP is the time-based variant of this algorithm, where a value T,
 * derived from a time reference and a time step, replaces the counter C
 * in the HOTP computation.
 *
 * See: https://datatracker.ietf.org/doc/html/rfc6238
 *
 * @param secret - static symmetric key known only to the token and the validation
 * service
 * @returns OTP
 */
export declare function totp(secret: string): Promise<string>;
/**
 * Remaining seconds until the next TOTP code is generated.
 *
 * @returns Remaining seconds
 */
export declare function timeLeft(): number;