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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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