From 7ce5ad1e78ad8c706539e787da2341f4f55df7cf Mon Sep 17 00:00:00 2001
From: Dustin Gedlich <DasDingGehtNicht@users.noreply.github.com>
Date: Thu, 11 Feb 2021 13:44:08 +0100
Subject: [PATCH] fix: fix gcm tag length truncation

---
 lib/cipherModes.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/cipherModes.js b/lib/cipherModes.js
index 339915cc1..8c4ea14bd 100644
--- a/lib/cipherModes.js
+++ b/lib/cipherModes.js
@@ -756,7 +756,7 @@ modes.gcm.prototype.afterFinish = function(output, options) {
   }
 
   // trim tag to length
-  this.tag.truncate(this.tag.length() % (this._tagLength / 8));
+  this.tag.truncate(this.tag.length() - (this._tagLength / 8));
 
   // check authentication tag
   if(options.decrypt && this.tag.bytes() !== this._tag) {