declare const otpDigitLength: readonly [6, 8, 10];
type OtpSecret = string | Buffer;
type OtpHashAlgorithm = "sha1" | "sha256" | "sha512";
type OtpSecretStringEncoding = "base32" | BufferEncoding;
type OtpDigitLength = (typeof otpDigitLength)[number];
interface HotpOptions {
	addChecksum?: boolean;
	algorithm?: OtpHashAlgorithm;
	digits?: OtpDigitLength;
	secretEncoding?: OtpSecretStringEncoding;
	truncationOffset?: number;
}
interface HotpBufferSecretOptions extends Omit<HotpOptions, "secretEncoding"> {}
interface HotpStringSecretOptions extends HotpOptions {}
interface HotpSpecificOptions extends Omit<HotpOptions, "algorithm"> {}
interface HotpSpecificBufferSecretOptions extends Omit<HotpSpecificOptions, "secretEncoding"> {}
interface HotpSpecificStringSecretOptions extends HotpSpecificOptions {}
declare function generateHotp(secret: Buffer, counter: number, options?: HotpBufferSecretOptions): string;
declare function generateHotp(secret: string, counter: number, options?: HotpStringSecretOptions): string;
declare function generateHotp(secret: OtpSecret, counter: number, options?: HotpOptions): string;
declare function generateHotpSha1(secret: Buffer, counter: number, options?: HotpSpecificBufferSecretOptions): string;
declare function generateHotpSha1(secret: string, counter: number, options?: HotpSpecificStringSecretOptions): string;
declare function generateHotpSha256(secret: Buffer, counter: number, options?: HotpSpecificBufferSecretOptions): string;
declare function generateHotpSha256(secret: string, counter: number, options?: HotpSpecificStringSecretOptions): string;
declare function generateHotpSha512(secret: Buffer, counter: number, options?: HotpSpecificBufferSecretOptions): string;
declare function generateHotpSha512(secret: string, counter: number, options?: HotpSpecificStringSecretOptions): string;
export { generateHotpSha512, generateHotpSha256, generateHotpSha1, generateHotp };