README

onetime

An one-time password generation library written in Go, implementing HOTP (RFC-4226) and TOTP (RFC-6238).

Example usage

Simple 6-digit HOTP code:

import "onetime"

var secret = []byte("SOME_SECRET")
var counter = 123456
var otp, _ = onetime.Simple(6)
var code = otp.HOTP(secret, counter)

Google authenticator style 8-digit TOTP code:

import "onetime"

var secret = []byte("SOME_SECRET")
var otp, _ = onetime.Simple(8)
var code = otp.TOTP(secret)

9-digit 5-second-step TOTP starting on midnight 2000-01-01 UTC, using SHA-256:

import (
    "crypto/sha256"
    "onetime"
    "time"
)

var secret = []byte("SOME_SECRET")
const ts = 5 * time.Second
var t = time.Date(2000, time.January, 1, 0, 0, 0, 0, time.UTC)
var otp = onetime.OneTimePassword{Digit: 9, TimeStep: ts, BaseTime: t, Hash: sha256.New}
var code = otp.TOTP(secret)

Documentation

Package doc can be found at godoc.org.

License

This library is released under a simplified BSD license.

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Documentation

Overview

    Package onetime provides a library for one-time password generation, implementing the HOTP and TOTP algorithms as specified by IETF RFC-4226 and RFC-6238.

    Example (Authenticator)
    Output:
    
    
    Example (Custom)
    Output:
    
    
    Example (Simple)
    Output:
    
    260040
    

    Index

    Examples

    Constants

    This section is empty.

    Variables

    This section is empty.

    Functions

    This section is empty.

    Types

    type OneTimePassword

    type OneTimePassword struct {
    	Digit    int              // Length of code generated
    	TimeStep time.Duration    // Length of each time step for TOTP
    	BaseTime time.Time        // The start time for TOTP step calculation
    	Hash     func() hash.Hash // Hash algorithm used with HMAC
    }

      OneTimePassword stores the configuration values relevant to HOTP/TOTP calculations.

      func Simple

      func Simple(digit int) (otp OneTimePassword, err error)

        Simple returns a new OneTimePassword with the specified HTOP code length, SHA-1 as the HMAC hash algorithm, the Unix epoch as the base time, and 30 seconds as the step length.

        func (*OneTimePassword) HOTP

        func (otp *OneTimePassword) HOTP(secret []byte, count uint64) uint

          HOTP returns a HOTP code with the given secret and counter.

          func (*OneTimePassword) TOTP

          func (otp *OneTimePassword) TOTP(secret []byte) uint

            TOTP returns a TOTP code calculated with the current time and the given secret.

            Source Files