mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-30 07:32:45 +00:00
145 lines
4.9 KiB
Markdown
145 lines
4.9 KiB
Markdown
# gorilla/securecookie
|
|
|
|
|
|
[](https://codecov.io/github/gorilla/securecookie)
|
|
[](https://godoc.org/github.com/gorilla/securecookie)
|
|
[](https://sourcegraph.com/github.com/gorilla/securecookie?badge)
|
|
|
|
|
|
|
|
securecookie encodes and decodes authenticated and optionally encrypted
|
|
cookie values.
|
|
|
|
Secure cookies can't be forged, because their values are validated using HMAC.
|
|
When encrypted, the content is also inaccessible to malicious eyes. It is still
|
|
recommended that sensitive data not be stored in cookies, and that HTTPS be used
|
|
to prevent cookie [replay attacks](https://en.wikipedia.org/wiki/Replay_attack).
|
|
|
|
## Examples
|
|
|
|
To use it, first create a new SecureCookie instance:
|
|
|
|
```go
|
|
// Hash keys should be at least 32 bytes long
|
|
var hashKey = []byte("very-secret")
|
|
// Block keys should be 16 bytes (AES-128) or 32 bytes (AES-256) long.
|
|
// Shorter keys may weaken the encryption used.
|
|
var blockKey = []byte("a-lot-secret")
|
|
var s = securecookie.New(hashKey, blockKey)
|
|
```
|
|
|
|
The hashKey is required, used to authenticate the cookie value using HMAC.
|
|
It is recommended to use a key with 32 or 64 bytes.
|
|
|
|
The blockKey is optional, used to encrypt the cookie value -- set it to nil
|
|
to not use encryption. If set, the length must correspond to the block size
|
|
of the encryption algorithm. For AES, used by default, valid lengths are
|
|
16, 24, or 32 bytes to select AES-128, AES-192, or AES-256.
|
|
|
|
Strong keys can be created using the convenience function
|
|
`GenerateRandomKey()`. Note that keys created using `GenerateRandomKey()` are not
|
|
automatically persisted. New keys will be created when the application is
|
|
restarted, and previously issued cookies will not be able to be decoded.
|
|
|
|
Once a SecureCookie instance is set, use it to encode a cookie value:
|
|
|
|
```go
|
|
func SetCookieHandler(w http.ResponseWriter, r *http.Request) {
|
|
value := map[string]string{
|
|
"foo": "bar",
|
|
}
|
|
if encoded, err := s.Encode("cookie-name", value); err == nil {
|
|
cookie := &http.Cookie{
|
|
Name: "cookie-name",
|
|
Value: encoded,
|
|
Path: "/",
|
|
Secure: true,
|
|
HttpOnly: true,
|
|
}
|
|
http.SetCookie(w, cookie)
|
|
}
|
|
}
|
|
```
|
|
|
|
Later, use the same SecureCookie instance to decode and validate a cookie
|
|
value:
|
|
|
|
```go
|
|
func ReadCookieHandler(w http.ResponseWriter, r *http.Request) {
|
|
if cookie, err := r.Cookie("cookie-name"); err == nil {
|
|
value := make(map[string]string)
|
|
if err = s2.Decode("cookie-name", cookie.Value, &value); err == nil {
|
|
fmt.Fprintf(w, "The value of foo is %q", value["foo"])
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
We stored a map[string]string, but secure cookies can hold any value that
|
|
can be encoded using `encoding/gob`. To store custom types, they must be
|
|
registered first using gob.Register(). For basic types this is not needed;
|
|
it works out of the box. An optional JSON encoder that uses `encoding/json` is
|
|
available for types compatible with JSON.
|
|
|
|
### Key Rotation
|
|
Rotating keys is an important part of any security strategy. The `EncodeMulti` and
|
|
`DecodeMulti` functions allow for multiple keys to be rotated in and out.
|
|
For example, let's take a system that stores keys in a map:
|
|
|
|
```go
|
|
// keys stored in a map will not be persisted between restarts
|
|
// a more persistent storage should be considered for production applications.
|
|
var cookies = map[string]*securecookie.SecureCookie{
|
|
"previous": securecookie.New(
|
|
securecookie.GenerateRandomKey(64),
|
|
securecookie.GenerateRandomKey(32),
|
|
),
|
|
"current": securecookie.New(
|
|
securecookie.GenerateRandomKey(64),
|
|
securecookie.GenerateRandomKey(32),
|
|
),
|
|
}
|
|
```
|
|
|
|
Using the current key to encode new cookies:
|
|
```go
|
|
func SetCookieHandler(w http.ResponseWriter, r *http.Request) {
|
|
value := map[string]string{
|
|
"foo": "bar",
|
|
}
|
|
if encoded, err := securecookie.EncodeMulti("cookie-name", value, cookies["current"]); err == nil {
|
|
cookie := &http.Cookie{
|
|
Name: "cookie-name",
|
|
Value: encoded,
|
|
Path: "/",
|
|
}
|
|
http.SetCookie(w, cookie)
|
|
}
|
|
}
|
|
```
|
|
|
|
Later, decode cookies. Check against all valid keys:
|
|
```go
|
|
func ReadCookieHandler(w http.ResponseWriter, r *http.Request) {
|
|
if cookie, err := r.Cookie("cookie-name"); err == nil {
|
|
value := make(map[string]string)
|
|
err = securecookie.DecodeMulti("cookie-name", cookie.Value, &value, cookies["current"], cookies["previous"])
|
|
if err == nil {
|
|
fmt.Fprintf(w, "The value of foo is %q", value["foo"])
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
Rotate the keys. This strategy allows previously issued cookies to be valid until the next rotation:
|
|
```go
|
|
func Rotate(newCookie *securecookie.SecureCookie) {
|
|
cookies["previous"] = cookies["current"]
|
|
cookies["current"] = newCookie
|
|
}
|
|
```
|
|
|
|
## License
|
|
|
|
BSD licensed. See the LICENSE file for details.
|