Revert "Update securecookie.go"

This reverts commit f14b1ebae2.

securecookie.go

@@ -118,8 +118,6 @@ type Codec interface {
 	Decode(name, value string, dst interface{}, maxAge ...int) error
 }
 
-var DefaultMaxLength = 1024 * 1024 // 1M
-
 // New returns a new SecureCookie.
 //
 // hashKey is required, used to authenticate values using HMAC. Create it using
@@ -140,7 +138,7 @@ func New(hashKey, blockKey []byte) *SecureCookie {
 		blockKey:  blockKey,
 		hashFunc:  sha256.New,
 		maxAge:    86400 * 30,
-		maxLength: DefaultMaxLength,
+		maxLength: 4096,
 		sz:        GobEncoder{},
 	}
 	if len(hashKey) == 0 {