### Initialize SecureCookie Instances for Key Rotation

Source: https://github.com/gorilla/securecookie/blob/main/README.md

Set up multiple SecureCookie instances for key rotation. This example demonstrates storing keys in a map, which is suitable for demonstration but requires persistent storage in production.

```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),
	),
}
```

--------------------------------

### Create a New SecureCookie Instance

Source: https://github.com/gorilla/securecookie/blob/main/README.md

Instantiate a new SecureCookie with hash and block keys. The hash key is required for authentication, and the block key is optional for encryption. Ensure keys are of appropriate lengths for security.

```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)
```

--------------------------------

### Decode Cookie with Multiple Keys

Source: https://github.com/gorilla/securecookie/blob/main/README.md

Decode a cookie value by checking against multiple keys, including current and previous ones. This is essential for seamless key rotation, ensuring older cookies remain valid.

```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"])
		}
	}
```

--------------------------------

### Encode Cookie with Multiple Keys

Source: https://github.com/gorilla/securecookie/blob/main/README.md

Encode a cookie value using a specific key from a set of keys. This is used when implementing key rotation, allowing new cookies to be encoded with the current active key.

```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)
	}
```

--------------------------------

### Rotate SecureCookie Keys

Source: https://github.com/gorilla/securecookie/blob/main/README.md

Update the active keys for cookie encoding and decoding. This function shifts the current key to previous and sets a new key as current, facilitating a secure key rotation strategy.

```go
func Rotate(newCookie *securecookie.SecureCookie) {
	cookies["previous"] = cookies["current"]
	cookies["current"] = newCookie
}
```

--------------------------------

### Encode Cookie Value

Source: https://github.com/gorilla/securecookie/blob/main/README.md

Encode a map into a secure cookie string. This function handles the creation of an authenticated and optionally encrypted cookie value. Ensure the cookie name and value are correctly provided.

```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)
	}
```

--------------------------------

### Decode and Validate Cookie Value

Source: https://github.com/gorilla/securecookie/blob/main/README.md

Decode and validate a secure cookie value. This function checks the cookie's integrity and decrypts its content if encryption was used. Ensure the cookie name matches the one used during encoding.

```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"])
		}
	}
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.