From c6a16ea57396658108f819447de60f8ae296d642 Mon Sep 17 00:00:00 2001
From: Jeffrey Walton <noloader@gmail.com>
Date: Thu, 28 Sep 2023 09:05:16 -0400
Subject: [PATCH] Add GenerateKeystream to HC256 This keeps HC-128 and HC-256
 consistent

---
 hc256.cpp | 13 +++++++++----
 hc256.h   |  2 ++
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/hc256.cpp b/hc256.cpp
index b0567615..3a93f21e 100644
--- a/hc256.cpp
+++ b/hc256.cpp
@@ -88,6 +88,14 @@ inline word32 HC256Policy::Generate() /*one step of the cipher*/
 	return (output);
 }
 
+void HC256Policy::GenerateKeystream(word32 keystream[4])
+{
+	keystream[0] = Generate();
+	keystream[1] = Generate();
+	keystream[2] = Generate();
+	keystream[3] = Generate();
+}
+
 void HC256Policy::CipherSetKey(const NameValuePairs &params, const byte *userKey, size_t keylen)
 {
 	CRYPTOPP_UNUSED(params); CRYPTOPP_UNUSED(keylen);
@@ -108,10 +116,7 @@ void HC256Policy::OperateKeystream(KeystreamOperation operation, byte *output, c
 	while (iterationCount--)
 	{
 		FixedSizeSecBlock<word32, 4> keystream;
-		keystream[0] = Generate();
-		keystream[1] = Generate();
-		keystream[2] = Generate();
-		keystream[3] = Generate();
+		GenerateKeystream(keystream);
 
 		CRYPTOPP_KEYSTREAM_OUTPUT_SWITCH(HC256_OUTPUT, BYTES_PER_ITERATION);
 	}
diff --git a/hc256.h b/hc256.h
index ccd1ca05..aa1e88ee 100644
--- a/hc256.h
+++ b/hc256.h
@@ -39,6 +39,8 @@ protected:
 
 	word32 H1(word32 u);
 	word32 H2(word32 u);
+
+	void GenerateKeystream(word32* keystream);
 	word32 Generate();
 
 private: