Add GenerateKeystream to HC256

This keeps HC-128 and HC-256 consistent
weidai11 · Sep 28, 2023 · c6a16ea · c6a16ea
1 parent 0bf8798
commit c6a16ea
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Showing 2 changed files with 11 additions and 4 deletions.
diff --git 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
@@ -39,6 +39,8 @@ class HC256Policy : public AdditiveCipherConcretePolicy<word32, 4>, public HC256
 
 	word32 H1(word32 u);
 	word32 H2(word32 u);
+
+	void GenerateKeystream(word32* keystream);
 	word32 Generate();
 
 private: