From e844beecc86dafca3e49b2ab2986c118e38ef1a4 Mon Sep 17 00:00:00 2001
From: Tom Smeding <hallo@tomsmeding.nl>
Date: Thu, 27 Oct 2016 18:15:49 +0200
Subject: Add double cast comment

---
 envelope.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/envelope.cpp b/envelope.cpp
index abf6e8f..0c995bd 100644
--- a/envelope.cpp
+++ b/envelope.cpp
@@ -59,6 +59,7 @@ namespace Envelope{
 
 	string decrypt(const string &data,const RSA::Key &privkey){
 		if(data.size()<2)throw invalid_argument("Envelope data length invalid");
+		//This double cast is necessary because of sign extension.
 		int encrkeylen=((uint16_t)(uint8_t)data[data.size()-2]<<8)+(uint8_t)data.back();
 		assert(encrkeylen<(1<<16));
 		if((int)data.size()<encrkeylen+2)throw invalid_argument("Envelope key format invalid");
-- 
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