From d5444a1292a4b67dea5d0278e169abb7aaad7a3a Mon Sep 17 00:00:00 2001
From: David Hook <dgh@bouncycastle.org>
Date: Tue, 7 Mar 2017 10:24:47 +1100
Subject: Fixed N4 calculation issue - see BJA-655

---
 crypto/src/crypto/modes/GOFBBlockCipher.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'crypto/src')

diff --git a/crypto/src/crypto/modes/GOFBBlockCipher.cs b/crypto/src/crypto/modes/GOFBBlockCipher.cs
index a91562549..4299f11a9 100644
--- a/crypto/src/crypto/modes/GOFBBlockCipher.cs
+++ b/crypto/src/crypto/modes/GOFBBlockCipher.cs
@@ -169,7 +169,11 @@ namespace Org.BouncyCastle.Crypto.Modes
 			}
 			N3 += C2;
 			N4 += C1;
-			intTobytes(N3, ofbV, 0);
+            if (N4 < C1)  // addition is mod (2**32 - 1)
+            {
+                N4++;
+            }
+            intTobytes(N3, ofbV, 0);
 			intTobytes(N4, ofbV, 4);
 
 			cipher.ProcessBlock(ofbV, 0, ofbOutV, 0);
-- 
cgit 1.4.1