From 127ffd31971b7261cebc80cb4a62c30754c05467 Mon Sep 17 00:00:00 2001
From: Tobe O <thosakwe@gmail.com>
Date: Fri, 16 Aug 2019 09:09:11 -0400
Subject: [PATCH] signCookie

---
 lib/src/cookie_signer.dart | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/lib/src/cookie_signer.dart b/lib/src/cookie_signer.dart
index 64747811..653a8ebb 100644
--- a/lib/src/cookie_signer.dart
+++ b/lib/src/cookie_signer.dart
@@ -27,5 +27,18 @@ class CookieSigner {
     }
   }
 
-  void signCookie(Cookie cookie) {}
+  /// **Overwrites** the value of a [cookie] with one that is signed
+  /// with the [hmac].
+  ///
+  /// The signature is:
+  /// `base64Url(cookie.value) + "." + base64Url(sig)`
+  ///
+  /// Where `sig` is the cookie's value, signed with the [hmac].
+  void signCookie(Cookie cookie) {
+    // base64Url(cookie) + "." + base64Url(sig)
+    var encodedCookie = base64Url.encode(cookie.value.codeUnits);
+    var sigBytes = hmac.convert(cookie.value.codeUnits).bytes;
+    var sig = base64Url.encode(sigBytes);
+    cookie.value = encodedCookie + '.' + sig;
+  }
 }