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Two factor authentication support (#630)

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* Initial commit for 2FA support

Signed-off-by: Andrew <write@imaginarycode.com>

* Add vendored files

* Add missing depends

* A few clean ups

* Added improvements, proper encryption

* Better encryption key

* Simplify "key" generation

* Make 2FA enrollment page more robust

* Fix typo

* Rename twofa/2FA to TwoFactor

* UNIQUE INDEX -> UNIQUE
This commit is contained in:
Andrew 2017-01-15 21:14:29 -05:00 • committed by Lunny Xiao
parent 64375d875b
commit 6dd096b7f0
40 changed files with 3395 additions and 8 deletions
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otp
Copyright (c) 2014, Paul Querna
This product includes software developed by
Paul Querna (http://paul.querna.org/).

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# otp: One Time Password utilities Go / Golang
[![GoDoc](https://godoc.org/github.com/pquerna/otp?status.svg)](https://godoc.org/github.com/pquerna/otp) [![Build Status](https://travis-ci.org/pquerna/otp.svg?branch=master)](https://travis-ci.org/pquerna/otp)
# Why One Time Passwords?
One Time Passwords (OTPs) are an mechanism to improve security over passwords alone. When a Time-based OTP (TOTP) is stored on a user's phone, and combined with something the user knows (Password), you have an easy on-ramp to [Multi-factor authentication](http://en.wikipedia.org/wiki/Multi-factor_authentication) without adding a dependency on a SMS provider. This Password and TOTP combination is used by many popular websites including Google, Github, Facebook, Salesforce and many others.
The `otp` library enables you to easily add TOTPs to your own application, increasing your user's security against mass-password breaches and malware.
Because TOTP is standardized and widely deployed, there are many [mobile clients and software implementations](http://en.wikipedia.org/wiki/Time-based_One-time_Password_Algorithm#Client_implementations).
## `otp` Supports:
* Generating QR Code images for easy user enrollment.
* Time-based One-time Password Algorithm (TOTP) (RFC 6238): Time based OTP, the most commonly used method.
* HMAC-based One-time Password Algorithm (HOTP) (RFC 4226): Counter based OTP, which TOTP is based upon.
* Generation and Validation of codes for either algorithm.
## Implementing TOTP in your application:
### User Enrollment
For an example of a working enrollment work flow, [Github has documented theirs](https://help.github.com/articles/configuring-two-factor-authentication-via-a-totp-mobile-app/
), but the basics are:
1. Generate new TOTP Key for a User. `key,_ := totp.Generate(...)`.
1. Display the Key's Secret and QR-Code for the User. `key.Secret()` and `key.Image(...)`.
1. Test that the user can successfully use their TOTP. `totp.Validate(...)`.
1. Store TOTP Secret for the User in your backend. `key.Secret()`
1. Provide the user with "recovery codes". (See Recovery Codes bellow)
### Code Generation
* In either TOTP or HOTP cases, use the `GenerateCode` function and a counter or
`time.Time` struct to generate a valid code compatible with most implementations.
* For uncommon or custom settings, or to catch unlikely errors, use `GenerateCodeCustom`
in either module.
### Validation
1. Prompt and validate User's password as normal.
1. If the user has TOTP enabled, prompt for TOTP passcode.
1. Retrieve the User's TOTP Secret from your backend.
1. Validate the user's passcode. `totp.Validate(...)`
### Recovery Codes
When a user loses access to their TOTP device, they would no longer have access to their account. Because TOTPs are often configured on mobile devices that can be lost, stolen or damaged, this is a common problem. For this reason many providers give their users "backup codes" or "recovery codes". These are a set of one time use codes that can be used instead of the TOTP. These can simply be randomly generated strings that you store in your backend. [Github's documentation provides an overview of the user experience](
https://help.github.com/articles/downloading-your-two-factor-authentication-recovery-codes/).
## Improvements, bugs, adding feature, etc:
Please [open issues in Github](https://github.com/pquerna/otp/issues) for ideas, bugs, and general thoughts. Pull requests are of course preferred :)
## License
`otp` is licensed under the [Apache License, Version 2.0](./LICENSE)

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/**
* Copyright 2014 Paul Querna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
// Package otp implements both HOTP and TOTP based
// one time passcodes in a Google Authenticator compatible manner.
//
// When adding a TOTP for a user, you must store the "secret" value
// persistently. It is recommend to store the secret in an encrypted field in your
// datastore. Due to how TOTP works, it is not possible to store a hash
// for the secret value like you would a password.
//
// To enroll a user, you must first generate an OTP for them. Google
// Authenticator supports using a QR code as an enrollment method:
//
// import (
// "github.com/pquerna/otp/totp"
//
// "bytes"
// "image/png"
// )
//
// key, err := totp.Generate(totp.GenerateOpts{
// Issuer: "Example.com",
// AccountName: "alice@example.com",
// })
//
// // Convert TOTP key into a QR code encoded as a PNG image.
// var buf bytes.Buffer
// img, err := key.Image(200, 200)
// png.Encode(&buf, img)
//
// // display the QR code to the user.
// display(buf.Bytes())
//
// // Now Validate that the user's successfully added the passcode.
// passcode := promptForPasscode()
// valid := totp.Validate(passcode, key.Secret())
//
// if valid {
// // User successfully used their TOTP, save it to your backend!
// storeSecret("alice@example.com", key.Secret())
// }
//
// Validating a TOTP passcode is very easy, just prompt the user for a passcode
// and retrieve the associated user's previously stored secret.
// import "github.com/pquerna/otp/totp"
//
// passcode := promptForPasscode()
// secret := getSecret("alice@example.com")
//
// valid := totp.Validate(passcode, secret)
//
// if valid {
// // Success! continue login process.
// }
package otp

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/**
* Copyright 2014 Paul Querna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package hotp
import (
"github.com/pquerna/otp"
"crypto/hmac"
"crypto/rand"
"crypto/subtle"
"encoding/base32"
"encoding/binary"
"fmt"
"math"
"net/url"
"strings"
)
const debug = false
// Validate a HOTP passcode given a counter and secret.
// This is a shortcut for ValidateCustom, with parameters that
// are compataible with Google-Authenticator.
func Validate(passcode string, counter uint64, secret string) bool {
rv, _ := ValidateCustom(
passcode,
counter,
secret,
ValidateOpts{
Digits: otp.DigitsSix,
Algorithm: otp.AlgorithmSHA1,
},
)
return rv
}
// ValidateOpts provides options for ValidateCustom().
type ValidateOpts struct {
// Digits as part of the input. Defaults to 6.
Digits otp.Digits
// Algorithm to use for HMAC. Defaults to SHA1.
Algorithm otp.Algorithm
}
// GenerateCode creates a HOTP passcode given a counter and secret.
// This is a shortcut for GenerateCodeCustom, with parameters that
// are compataible with Google-Authenticator.
func GenerateCode(secret string, counter uint64) (string, error) {
return GenerateCodeCustom(secret, counter, ValidateOpts{
Digits: otp.DigitsSix,
Algorithm: otp.AlgorithmSHA1,
})
}
// GenerateCodeCustom uses a counter and secret value and options struct to
// create a passcode.
func GenerateCodeCustom(secret string, counter uint64, opts ValidateOpts) (passcode string, err error) {
secretBytes, err := base32.StdEncoding.DecodeString(secret)
if err != nil {
return "", otp.ErrValidateSecretInvalidBase32
}
buf := make([]byte, 8)
mac := hmac.New(opts.Algorithm.Hash, secretBytes)
binary.BigEndian.PutUint64(buf, counter)
if debug {
fmt.Printf("counter=%v\n", counter)
fmt.Printf("buf=%v\n", buf)
}
mac.Write(buf)
sum := mac.Sum(nil)
// "Dynamic truncation" in RFC 4226
// http://tools.ietf.org/html/rfc4226#section-5.4
offset := sum[len(sum)-1] & 0xf
value := int64(((int(sum[offset]) & 0x7f) << 24) |
((int(sum[offset+1] & 0xff)) << 16) |
((int(sum[offset+2] & 0xff)) << 8) |
(int(sum[offset+3]) & 0xff))
l := opts.Digits.Length()
mod := int32(value % int64(math.Pow10(l)))
if debug {
fmt.Printf("offset=%v\n", offset)
fmt.Printf("value=%v\n", value)
fmt.Printf("mod'ed=%v\n", mod)
}
return opts.Digits.Format(mod), nil
}
// ValidateCustom validates an HOTP with customizable options. Most users should
// use Validate().
func ValidateCustom(passcode string, counter uint64, secret string, opts ValidateOpts) (bool, error) {
passcode = strings.TrimSpace(passcode)
if len(passcode) != opts.Digits.Length() {
return false, otp.ErrValidateInputInvalidLength
}
otpstr, err := GenerateCodeCustom(secret, counter, opts)
if err != nil {
return false, err
}
if subtle.ConstantTimeCompare([]byte(otpstr), []byte(passcode)) == 1 {
return true, nil
}
return false, nil
}
// GenerateOpts provides options for .Generate()
type GenerateOpts struct {
// Name of the issuing Organization/Company.
Issuer string
// Name of the User's Account (eg, email address)
AccountName string
// Size in size of the generated Secret. Defaults to 10 bytes.
SecretSize uint
// Digits to request. Defaults to 6.
Digits otp.Digits
// Algorithm to use for HMAC. Defaults to SHA1.
Algorithm otp.Algorithm
}
// Generate creates a new HOTP Key.
func Generate(opts GenerateOpts) (*otp.Key, error) {
// url encode the Issuer/AccountName
if opts.Issuer == "" {
return nil, otp.ErrGenerateMissingIssuer
}
if opts.AccountName == "" {
return nil, otp.ErrGenerateMissingAccountName
}
if opts.SecretSize == 0 {
opts.SecretSize = 10
}
// otpauth://totp/Example:alice@google.com?secret=JBSWY3DPEHPK3PXP&issuer=Example
v := url.Values{}
secret := make([]byte, opts.SecretSize)
_, err := rand.Read(secret)
if err != nil {
return nil, err
}
v.Set("secret", base32.StdEncoding.EncodeToString(secret))
v.Set("issuer", opts.Issuer)
v.Set("algorithm", opts.Algorithm.String())
v.Set("digits", opts.Digits.String())
u := url.URL{
Scheme: "otpauth",
Host: "hotp",
Path: "/" + opts.Issuer + ":" + opts.AccountName,
RawQuery: v.Encode(),
}
return otp.NewKeyFromURL(u.String())
}

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/**
* Copyright 2014 Paul Querna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package otp
import (
"github.com/boombuler/barcode"
"github.com/boombuler/barcode/qr"
"crypto/md5"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"errors"
"fmt"
"hash"
"image"
"net/url"
"strings"
)
// Error when attempting to convert the secret from base32 to raw bytes.
var ErrValidateSecretInvalidBase32 = errors.New("Decoding of secret as base32 failed.")
// The user provided passcode length was not expected.
var ErrValidateInputInvalidLength = errors.New("Input length unexpected")
// When generating a Key, the Issuer must be set.
var ErrGenerateMissingIssuer = errors.New("Issuer must be set")
// When generating a Key, the Account Name must be set.
var ErrGenerateMissingAccountName = errors.New("AccountName must be set")
// Key represents an TOTP or HTOP key.
type Key struct {
orig string
url *url.URL
}
// NewKeyFromURL creates a new Key from an TOTP or HOTP url.
//
// The URL format is documented here:
// https://code.google.com/p/google-authenticator/wiki/KeyUriFormat
//
func NewKeyFromURL(orig string) (*Key, error) {
u, err := url.Parse(orig)
if err != nil {
return nil, err
}
return &Key{
orig: orig,
url: u,
}, nil
}
func (k *Key) String() string {
return k.orig
}
// Image returns an QR-Code image of the specified width and height,
// suitable for use by many clients like Google-Authenricator
// to enroll a user's TOTP/HOTP key.
func (k *Key) Image(width int, height int) (image.Image, error) {
b, err := qr.Encode(k.orig, qr.M, qr.Auto)
if err != nil {
return nil, err
}
b, err = barcode.Scale(b, width, height)
if err != nil {
return nil, err
}
return b, nil
}
// Type returns "hotp" or "totp".
func (k *Key) Type() string {
return k.url.Host
}
// Issuer returns the name of the issuing organization.
func (k *Key) Issuer() string {
q := k.url.Query()
issuer := q.Get("issuer")
if issuer != "" {
return issuer
}
p := strings.TrimPrefix(k.url.Path, "/")
i := strings.Index(p, ":")
if i == -1 {
return ""
}
return p[:i]
}
// AccountName returns the name of the user's account.
func (k *Key) AccountName() string {
p := strings.TrimPrefix(k.url.Path, "/")
i := strings.Index(p, ":")
if i == -1 {
return p
}
return p[i+1:]
}
// Secret returns the opaque secret for this Key.
func (k *Key) Secret() string {
q := k.url.Query()
return q.Get("secret")
}
// Algorithm represents the hashing function to use in the HMAC
// operation needed for OTPs.
type Algorithm int
const (
AlgorithmSHA1 Algorithm = iota
AlgorithmSHA256
AlgorithmSHA512
AlgorithmMD5
)
func (a Algorithm) String() string {
switch a {
case AlgorithmSHA1:
return "SHA1"
case AlgorithmSHA256:
return "SHA256"
case AlgorithmSHA512:
return "SHA512"
case AlgorithmMD5:
return "MD5"
}
panic("unreached")
}
func (a Algorithm) Hash() hash.Hash {
switch a {
case AlgorithmSHA1:
return sha1.New()
case AlgorithmSHA256:
return sha256.New()
case AlgorithmSHA512:
return sha512.New()
case AlgorithmMD5:
return md5.New()
}
panic("unreached")
}
// Digits represents the number of digits present in the
// user's OTP passcode. Six and Eight are the most common values.
type Digits int
const (
DigitsSix Digits = 6
DigitsEight Digits = 8
)
// Format converts an integer into the zero-filled size for this Digits.
func (d Digits) Format(in int32) string {
f := fmt.Sprintf("%%0%dd", d)
return fmt.Sprintf(f, in)
}
// Length returns the number of characters for this Digits.
func (d Digits) Length() int {
return int(d)
}
func (d Digits) String() string {
return fmt.Sprintf("%d", d)
}

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/**
* Copyright 2014 Paul Querna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package totp
import (
"github.com/pquerna/otp"
"github.com/pquerna/otp/hotp"
"crypto/rand"
"encoding/base32"
"math"
"net/url"
"strconv"
"time"
)
// Validate a TOTP using the current time.
// A shortcut for ValidateCustom, Validate uses a configuration
// that is compatible with Google-Authenticator and most clients.
func Validate(passcode string, secret string) bool {
rv, _ := ValidateCustom(
passcode,
secret,
time.Now().UTC(),
ValidateOpts{
Period: 30,
Skew: 1,
Digits: otp.DigitsSix,
Algorithm: otp.AlgorithmSHA1,
},
)
return rv
}
// GenerateCode creates a TOTP token using the current time.
// A shortcut for GenerateCodeCustom, GenerateCode uses a configuration
// that is compatible with Google-Authenticator and most clients.
func GenerateCode(secret string, t time.Time) (string, error) {
return GenerateCodeCustom(secret, t, ValidateOpts{
Period: 30,
Skew: 1,
Digits: otp.DigitsSix,
Algorithm: otp.AlgorithmSHA1,
})
}
// ValidateOpts provides options for ValidateCustom().
type ValidateOpts struct {
// Number of seconds a TOTP hash is valid for. Defaults to 30 seconds.
Period uint
// Periods before or after the current time to allow. Value of 1 allows up to Period
// of either side of the specified time. Defaults to 0 allowed skews. Values greater
// than 1 are likely sketchy.
Skew uint
// Digits as part of the input. Defaults to 6.
Digits otp.Digits
// Algorithm to use for HMAC. Defaults to SHA1.
Algorithm otp.Algorithm
}
// GenerateCodeCustom takes a timepoint and produces a passcode using a
// secret and the provided opts. (Under the hood, this is making an adapted
// call to hotp.GenerateCodeCustom)
func GenerateCodeCustom(secret string, t time.Time, opts ValidateOpts) (passcode string, err error) {
if opts.Period == 0 {
opts.Period = 30
}
counter := uint64(math.Floor(float64(t.Unix()) / float64(opts.Period)))
passcode, err = hotp.GenerateCodeCustom(secret, counter, hotp.ValidateOpts{
Digits: opts.Digits,
Algorithm: opts.Algorithm,
})
if err != nil {
return "", err
}
return passcode, nil
}
// ValidateCustom validates a TOTP given a user specified time and custom options.
// Most users should use Validate() to provide an interpolatable TOTP experience.
func ValidateCustom(passcode string, secret string, t time.Time, opts ValidateOpts) (bool, error) {
if opts.Period == 0 {
opts.Period = 30
}
counters := []uint64{}
counter := int64(math.Floor(float64(t.Unix()) / float64(opts.Period)))
counters = append(counters, uint64(counter))
for i := 1; i <= int(opts.Skew); i++ {
counters = append(counters, uint64(counter+int64(i)))
counters = append(counters, uint64(counter-int64(i)))
}
for _, counter := range counters {
rv, err := hotp.ValidateCustom(passcode, counter, secret, hotp.ValidateOpts{
Digits: opts.Digits,
Algorithm: opts.Algorithm,
})
if err != nil {
return false, err
}
if rv == true {
return true, nil
}
}
return false, nil
}
// GenerateOpts provides options for Generate(). The default values
// are compatible with Google-Authenticator.
type GenerateOpts struct {
// Name of the issuing Organization/Company.
Issuer string
// Name of the User's Account (eg, email address)
AccountName string
// Number of seconds a TOTP hash is valid for. Defaults to 30 seconds.
Period uint
// Size in size of the generated Secret. Defaults to 10 bytes.
SecretSize uint
// Digits to request. Defaults to 6.
Digits otp.Digits
// Algorithm to use for HMAC. Defaults to SHA1.
Algorithm otp.Algorithm
}
// Generate a new TOTP Key.
func Generate(opts GenerateOpts) (*otp.Key, error) {
// url encode the Issuer/AccountName
if opts.Issuer == "" {
return nil, otp.ErrGenerateMissingIssuer
}
if opts.AccountName == "" {
return nil, otp.ErrGenerateMissingAccountName
}
if opts.Period == 0 {
opts.Period = 30
}
if opts.SecretSize == 0 {
opts.SecretSize = 10
}
if opts.Digits == 0 {
opts.Digits = otp.DigitsSix
}
// otpauth://totp/Example:alice@google.com?secret=JBSWY3DPEHPK3PXP&issuer=Example
v := url.Values{}
secret := make([]byte, opts.SecretSize)
_, err := rand.Read(secret)
if err != nil {
return nil, err
}
v.Set("secret", base32.StdEncoding.EncodeToString(secret))
v.Set("issuer", opts.Issuer)
v.Set("period", strconv.FormatUint(uint64(opts.Period), 10))
v.Set("algorithm", opts.Algorithm.String())
v.Set("digits", opts.Digits.String())
u := url.URL{
Scheme: "otpauth",
Host: "totp",
Path: "/" + opts.Issuer + ":" + opts.AccountName,
RawQuery: v.Encode(),
}
return otp.NewKeyFromURL(u.String())
}