totp

TOTP

This project is a minimalistic implementation of RFC 4226 and RFC 6238 in Go. SHA1, SHA2-256, and SHA2-512 are currently supported as hash functions.

Only base-32 keys are supported.

Supported hash functions: SHA1, SHA2-256, and SHA2-512.

Usage Overview

package main

import (
	"fmt"
	"log"

	"codeberg.org/w8x0/totp"
)

func main() {
	// Generates a 160-bit secret in base-32-encoding
	base32Secret, err := totp.GenerateSecret(20)
	if err != nil {
		log.Fatalf("main: GenerateSecret returned an error: %v", err)
	}
	fmt.Println(base32Secret) // Prints "4W2X5IJNBME2R3VUMLREVYXP3H2OFKP2"

	totp, err := totp.GenerateDefault(base32Secret)
	if err != nil {
		log.Fatalf("main: GenerateDefault returned an error: %v", err)
	}
	fmt.Println(totp) // Prints "075151" (a 6-digit TOTP)

	totp, err = totp.GenerateVerbose(
		base32Secret,
		"SHA2-512", // Tell Generate to use the SHA2-512 hash function
		8, // Number of digits = 8
		45) // Time-step = 45 seconds
	if err != nil {
		log.Fatalf("main: GenerateVerbose returned an error: %v", err)
	}
	fmt.Println(totp) // Prints "90065898" (an 8-digit TOTP)
}

You can also validate TOTP parameters using ValidateVerbose and Validate:

err := ValidateVerbose("4W2X5IJNBME2R3VUMLREVYXP3H2OFKP2", "SHA1", 12, 30)
if err != nil {
	log.Fatal(err) // "Digits cannot be greater than 10."
}

err = Validate("JBSWY3DPEHPK3PXP1298")
if err != nil {
	log.Fatal(err) // "illegal base32 data at input byte 16"
}