/
auth.go
275 lines (224 loc) · 5.74 KB
/
auth.go
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package auth
import (
"crypto/hmac"
"crypto/rand"
"crypto/sha256"
"encoding/asn1"
"encoding/binary"
"errors"
"io"
"net/http"
"regexp"
"time"
"golang.org/x/crypto/chacha20poly1305"
"golang.org/x/crypto/scrypt"
"github.com/cozy/cozy-apps-registry/errshttp"
)
// Editors is the default registry for editors. In theory, I would have
// preferred to avoid using a global variable, or moved it to the base package.
// But it is quite complex to do so, so let's keep it here for now.
var Editors *EditorRegistry
const (
secretLen = 32
saltsLen = 16
)
var (
ErrEditorNotFound = errshttp.NewError(http.StatusNotFound, "Editor not found")
ErrEditorExists = errshttp.NewError(http.StatusConflict, "Editor already exists")
ErrBadEditorName = errshttp.NewError(http.StatusBadRequest, "Editor name should only contain alphanumeric characters")
ErrMissingPassphrase = errors.New("Missing passphrase")
)
var editorReg = regexp.MustCompile("^[A-Za-z][A-Za-z0-9]*$")
type (
EditorRegistry struct {
Vault
}
Vault interface {
GetEditor(editorName string) (*Editor, error)
CreateEditor(editor *Editor) error
UpdateEditor(editor *Editor) error
DeleteEditor(editor *Editor) error
AllEditors() ([]*Editor, error)
}
Editor struct {
name string
editorSalt []byte
masterSalt []byte
autoPublication bool
revocationCounters map[string]int
}
)
func NewEditorRegistry(vault Vault) *EditorRegistry {
return &EditorRegistry{vault}
}
func CheckEditorName(editorName string) error {
if editorName == "" || !editorReg.MatchString(editorName) {
return ErrBadEditorName
}
return nil
}
func VerifyTokenAuthentication(masterSecret, token []byte) bool {
_, ok := verifyToken(masterSecret, token, nil)
return ok
}
func verifyToken(secret, token, additionalData []byte) ([]byte, bool) {
if len(secret) != secretLen {
panic("master secret has no correct length")
}
offset := len(token) - 32
if offset < 0 {
return nil, false
}
var expectedMac []byte
msg, msgMac := token[:offset], token[offset:]
{
buf := append(additionalData, msg...)
mac := hmac.New(sha256.New, secret)
if _, err := mac.Write(buf); err != nil {
return nil, false
}
expectedMac = mac.Sum(nil)
}
if !hmac.Equal(msgMac, expectedMac) {
return nil, false
}
// the mac does not contain max age field
if len(msg) < 8 {
return nil, false
}
value := msg[8:]
t := int64(binary.BigEndian.Uint64(msg))
if t == 0 {
return value, true
}
if !time.Now().UTC().Before(time.Unix(t, 0)) {
return nil, false
}
return value, true
}
func generateToken(secret, msg, additionalData []byte, maxAge time.Duration) ([]byte, error) {
if len(secret) != secretLen {
panic("master secret has no correct length")
}
if maxAge < 0 {
panic("maxAge is negative")
}
msg = append(make([]byte, 8), msg...)
if maxAge > 0 {
binary.BigEndian.PutUint64(msg, uint64(time.Now().UTC().Add(maxAge).Unix()))
}
var computedMac []byte
{
buf := append(additionalData, msg...)
mac := hmac.New(sha256.New, secret)
if _, err := mac.Write(buf); err != nil {
panic(err)
}
computedMac = mac.Sum(nil)
}
msg = append(msg, computedMac...)
return msg, nil
}
func (r *EditorRegistry) CreateEditorWithoutPublicKey(editorName string, autoPublication bool) (*Editor, error) {
if err := CheckEditorName(editorName); err != nil {
return nil, err
}
editor := &Editor{
name: editorName,
editorSalt: readRand(saltsLen),
masterSalt: readRand(saltsLen),
autoPublication: autoPublication,
}
if err := r.CreateEditor(editor); err != nil {
return nil, err
}
return editor, nil
}
func (r *EditorRegistry) RevokeMasterTokens(editor *Editor) error {
editor.masterSalt = readRand(saltsLen)
return r.UpdateEditor(editor)
}
func (r *EditorRegistry) RevokeEditorTokens(editor *Editor) error {
editor.editorSalt = readRand(saltsLen)
return r.UpdateEditor(editor)
}
func DecryptMasterSecret(content, passphrase []byte) ([]byte, error) {
var encryptedSecret struct {
Salt []byte
Nonce []byte
Secret []byte
}
if len(passphrase) == 0 {
return nil, ErrMissingPassphrase
}
if _, err := asn1.Unmarshal(content, &encryptedSecret); err != nil {
return nil, err
}
if len(encryptedSecret.Salt) != 16 || len(encryptedSecret.Nonce) != 12 {
return nil, errors.New("Bad secret file")
}
N := 16384
r := 8
p := 1
derivedKey, err := scrypt.Key(passphrase, encryptedSecret.Salt, N, r, p, 32)
if err != nil {
return nil, err
}
aead, err := chacha20poly1305.New(derivedKey)
if err != nil {
return nil, err
}
secret, err := aead.Open(nil, encryptedSecret.Nonce, encryptedSecret.Secret, nil)
if err != nil {
return nil, err
}
if len(secret) != secretLen {
return nil, errors.New("Bad secret file: bad length of secret")
}
return secret, nil
}
func IsSecretClear(secret []byte) bool {
return len(secret) == secretLen
}
func EncryptMasterSecret(secret, passphrase []byte) ([]byte, error) {
var encryptedSecret struct {
Salt []byte
Nonce []byte
Secret []byte
}
if len(secret) != secretLen {
panic("Bad len for master secret")
}
if len(passphrase) == 0 {
return nil, ErrMissingPassphrase
}
salt := readRand(16)
nonce := readRand(12)
N := 16384
r := 8
p := 1
derivedKey, err := scrypt.Key(passphrase, salt, N, r, p, 32)
if err != nil {
return nil, err
}
aead, err := chacha20poly1305.New(derivedKey)
if err != nil {
return nil, err
}
encrypted := aead.Seal(nil, nonce, secret, nil)
encryptedSecret.Nonce = nonce
encryptedSecret.Salt = salt
encryptedSecret.Secret = encrypted
return asn1.Marshal(encryptedSecret)
}
func GenerateMasterSecret() []byte {
return readRand(secretLen)
}
func readRand(n int) []byte {
b := make([]byte, n)
_, err := io.ReadFull(rand.Reader, b)
if err != nil {
panic(err)
}
return b
}