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// Copyright 2017 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package models
import (
"crypto/aes"
"crypto/cipher"
"crypto/md5"
"crypto/rand"
"crypto/sha256"
"crypto/subtle"
"encoding/base64"
"errors"
"fmt"
"io"
"github.com/pquerna/otp/totp"
"golang.org/x/crypto/pbkdf2"
"code.gitea.io/gitea/modules/generate"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
)
// TwoFactor represents a two-factor authentication token.
type TwoFactor struct {
ID int64 `xorm:"pk autoincr"`
UID int64 `xorm:"UNIQUE"`
Secret string
ScratchSalt string
ScratchHash string
LastUsedPasscode string `xorm:"VARCHAR(10)"`
CreatedUnix util.TimeStamp `xorm:"INDEX created"`
UpdatedUnix util.TimeStamp `xorm:"INDEX updated"`
}
// GenerateScratchToken recreates the scratch token the user is using.
func (t *TwoFactor) GenerateScratchToken() (string, error) {
token, err := generate.GetRandomString(8)
if err != nil {
return "", err
}
t.ScratchSalt, _ = generate.GetRandomString(10)
t.ScratchHash = hashToken(token, t.ScratchSalt)
return token, nil
}
func hashToken(token, salt string) string {
tempHash := pbkdf2.Key([]byte(token), []byte(salt), 10000, 50, sha256.New)
return fmt.Sprintf("%x", tempHash)
}
// VerifyScratchToken verifies if the specified scratch token is valid.
func (t *TwoFactor) VerifyScratchToken(token string) bool {
if len(token) == 0 {
return false
}
tempHash := hashToken(token, t.ScratchSalt)
return subtle.ConstantTimeCompare([]byte(t.ScratchHash), []byte(tempHash)) == 1
}
func (t *TwoFactor) getEncryptionKey() []byte {
k := md5.Sum([]byte(setting.SecretKey))
return k[:]
}
// SetSecret sets the 2FA secret.
func (t *TwoFactor) SetSecret(secret string) error {
secretBytes, err := aesEncrypt(t.getEncryptionKey(), []byte(secret))
if err != nil {
return err
}
t.Secret = base64.StdEncoding.EncodeToString(secretBytes)
return nil
}
// ValidateTOTP validates the provided passcode.
func (t *TwoFactor) ValidateTOTP(passcode string) (bool, error) {
decodedStoredSecret, err := base64.StdEncoding.DecodeString(t.Secret)
if err != nil {
return false, err
}
secret, err := aesDecrypt(t.getEncryptionKey(), decodedStoredSecret)
if err != nil {
return false, err
}
secretStr := string(secret)
return totp.Validate(passcode, secretStr), nil
}
// aesEncrypt encrypts text and given key with AES.
func aesEncrypt(key, text []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
b := base64.StdEncoding.EncodeToString(text)
ciphertext := make([]byte, aes.BlockSize+len(b))
iv := ciphertext[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
cfb := cipher.NewCFBEncrypter(block, iv)
cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(b))
return ciphertext, nil
}
// aesDecrypt decrypts text and given key with AES.
func aesDecrypt(key, text []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
if len(text) < aes.BlockSize {
return nil, errors.New("ciphertext too short")
}
iv := text[:aes.BlockSize]
text = text[aes.BlockSize:]
cfb := cipher.NewCFBDecrypter(block, iv)
cfb.XORKeyStream(text, text)
data, err := base64.StdEncoding.DecodeString(string(text))
if err != nil {
return nil, err
}
return data, nil
}
// NewTwoFactor creates a new two-factor authentication token.
func NewTwoFactor(t *TwoFactor) error {
_, err := t.GenerateScratchToken()
if err != nil {
return err
}
_, err = x.Insert(t)
return err
}
// UpdateTwoFactor updates a two-factor authentication token.
func UpdateTwoFactor(t *TwoFactor) error {
_, err := x.ID(t.ID).AllCols().Update(t)
return err
}
// GetTwoFactorByUID returns the two-factor authentication token associated with
// the user, if any.
func GetTwoFactorByUID(uid int64) (*TwoFactor, error) {
twofa := &TwoFactor{UID: uid}
has, err := x.Get(twofa)
if err != nil {
return nil, err
} else if !has {
return nil, ErrTwoFactorNotEnrolled{uid}
}
return twofa, nil
}
// DeleteTwoFactorByID deletes two-factor authentication token by given ID.
func DeleteTwoFactorByID(id, userID int64) error {
cnt, err := x.ID(id).Delete(&TwoFactor{
UID: userID,
})
if err != nil {
return err
} else if cnt != 1 {
return ErrTwoFactorNotEnrolled{userID}
}
return nil
}
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