From 5e5fd3c47ef3d8bfd29a31311e1d933c6138ed44 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 16 Apr 2016 15:49:56 +0300
Subject: [PATCH 1/1] Avoid shuffling the data around in memory so much

---
 source/sha2.cpp | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/source/sha2.cpp b/source/sha2.cpp
index 3823643..c0cb1a1 100644
--- a/source/sha2.cpp
+++ b/source/sha2.cpp
@@ -79,8 +79,8 @@ void SHA2<C>::process_block(const char *data)
 	for(unsigned i=16; i<Constants::N_ROUNDS; ++i)
 	{
 		WordType *block = message_blocks+i;
-		WordType s1 = (rotate_right(block[-2], sigma[9]) ^ rotate_right(block[-2], sigma[10]) ^ (block[-2]>>sigma[11]));
-		WordType s0 = (rotate_right(block[-15], sigma[6]) ^ rotate_right(block[-15], sigma[7]) ^ (block[-15]>>sigma[8]));
+		WordType s1 = rotate_right(block[-2], sigma[9]) ^ rotate_right(block[-2], sigma[10]) ^ (block[-2]>>sigma[11]);
+		WordType s0 = rotate_right(block[-15], sigma[6]) ^ rotate_right(block[-15], sigma[7]) ^ (block[-15]>>sigma[8]);
 		*block =  s1+block[-7]+s0+block[-16];
 	}
 
@@ -89,20 +89,24 @@ void SHA2<C>::process_block(const char *data)
 
 	for(unsigned i=0; i<Constants::N_ROUNDS; ++i)
 	{
-		WordType s1 = (rotate_right(values[4], sigma[3]) ^ rotate_right(values[4], sigma[4]) ^ rotate_right(values[4], sigma[5]));
-		WordType ch = ((values[4]&values[5]) ^ (~values[4]&values[6]));
-		WordType temp1 = values[7]+s1+ch+Constants::round_constants[i]+message_blocks[i];
-		WordType s0 = (rotate_right(values[0], sigma[0]) ^ rotate_right(values[0], sigma[1]) ^ rotate_right(values[0], sigma[2]));
-		WordType maj = ((values[0]&values[1]) ^ (values[0]&values[2]) ^ (values[1]&values[2]));
+		const WordType &a = values[(88-i)&7];
+		const WordType &b = values[(89-i)&7];
+		const WordType &c = values[(90-i)&7];
+		WordType &d = values[(91-i)&7];
+		const WordType &e = values[(92-i)&7];
+		const WordType &f = values[(93-i)&7];
+		const WordType &g = values[(94-i)&7];
+		WordType &h = values[(95-i)&7];
+
+		WordType s1 = rotate_right(e, sigma[3]) ^ rotate_right(e, sigma[4]) ^ rotate_right(e, sigma[5]);
+		WordType ch = (e&f) ^ (~e&g);
+		WordType temp1 = h+s1+ch+Constants::round_constants[i]+message_blocks[i];
+		WordType s0 = rotate_right(a, sigma[0]) ^ rotate_right(a, sigma[1]) ^ rotate_right(a, sigma[2]);
+		WordType maj = (a&b) ^ (a&c) ^ (b&c);
 		WordType temp2 = s0+maj;
-		values[7] = values[6];
-		values[6] = values[5];
-		values[5] = values[4];
-		values[4] = values[3]+temp1;
-		values[3] = values[2];
-		values[2] = values[1];
-		values[1] = values[0];
-		values[0] = temp1+temp2;
+
+		d += temp1;       // Will be e next round
+		h = temp1+temp2;  // Will be a next round
 	}
 
 	for(unsigned i=0; i<8; ++i)
-- 
2.43.0