From 352083b1d06f73ea571ff4804d4169630e3eab88 Mon Sep 17 00:00:00 2001
From: Jeffrey Walton <noloader@gmail.com>
Date: Thu, 25 Oct 2018 08:24:13 -0400
Subject: [PATCH] Cleanup HC128 and HC256 OperateKeystream

---
 hc128.cpp | 10 ++++++----
 hc256.cpp | 32 ++++++++++++++++++++------------
 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/hc128.cpp b/hc128.cpp
index 682344c5..b734d6e5 100644
--- a/hc128.cpp
+++ b/hc128.cpp
@@ -200,8 +200,7 @@ void HC128Policy::CipherSetKey(const NameValuePairs &params, const byte *userKey
 
 void HC128Policy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
 {
-	size_t msglen = GetBytesPerIteration() * iterationCount;
-	while (msglen >= 64)
+	while (iterationCount--)
 	{
 		word32 keystream[16];
 		GenerateKeystream(keystream);
@@ -231,9 +230,12 @@ void HC128Policy::OperateKeystream(KeystreamOperation operation, byte *output, c
 		//  keystream is written to the output buffer. The optional part is
 		//  adding the input buffer and keystream.
 		if ((operation & INPUT_NULL) != INPUT_NULL)
-			xorbuf(output, input, 64);
+		{
+			xorbuf(output, input, BYTES_PER_ITERATION);
+			input += BYTES_PER_ITERATION;
+		}
 
-		msglen -= 64; input += 64; output += 64;
+		output += BYTES_PER_ITERATION;
 	}
 }
 
diff --git a/hc256.cpp b/hc256.cpp
index aa64c648..f8ec989f 100644
--- a/hc256.cpp
+++ b/hc256.cpp
@@ -94,19 +94,27 @@ void HC256Policy::CipherSetKey(const NameValuePairs &params, const byte *userKey
 
 void HC256Policy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
 {
-	size_t msglen = GetBytesPerIteration() * iterationCount;
-	byte* out = output;
-	for (size_t i = 0; i < (msglen >> 2); i++, out += 4)
-		PutWord(false, LITTLE_ENDIAN_ORDER, out, Generate());
+	while (iterationCount--)
+	{
+		PutWord(false, LITTLE_ENDIAN_ORDER, output +  0, Generate());
+		PutWord(false, LITTLE_ENDIAN_ORDER, output +  4, Generate());
+		PutWord(false, LITTLE_ENDIAN_ORDER, output +  8, Generate());
+		PutWord(false, LITTLE_ENDIAN_ORDER, output + 12, Generate());
 
-	// If AdditiveCipherTemplate does not have an accumulated keystream
-	//  then it will ask OperateKeystream to generate one. Optionally it
-	//  will ask for an XOR of the input with the keystream while
-	//  writing the result to the output buffer. In all cases the
-	//  keystream is written to the output buffer. The optional part is
-	//  adding the input buffer and keystream.
-	if ((operation & INPUT_NULL) != INPUT_NULL)
-		xorbuf(output, input, msglen);
+		// If AdditiveCipherTemplate does not have an accumulated keystream
+		//  then it will ask OperateKeystream to generate one. Optionally it
+		//  will ask for an XOR of the input with the keystream while
+		//  writing the result to the output buffer. In all cases the
+		//  keystream is written to the output buffer. The optional part is
+		//  adding the input buffer and keystream.
+		if ((operation & INPUT_NULL) != INPUT_NULL)
+		{
+			xorbuf(output, input, BYTES_PER_ITERATION);
+			input += BYTES_PER_ITERATION;
+		}
+
+		output += BYTES_PER_ITERATION;
+	}
 }
 
 void HC256Policy::CipherResynchronize(byte *keystreamBuffer, const byte *iv, size_t length)