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-rw-r--r--lib/alg-sha256.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/lib/alg-sha256.c b/lib/alg-sha256.c
index f448e4f..f83a4e1 100644
--- a/lib/alg-sha256.c
+++ b/lib/alg-sha256.c
@@ -1,6 +1,6 @@
/*-
* Copyright 2005-2016 Colin Percival
- * Copyright 2016-2018 Alexander Peslyak
+ * Copyright 2016-2018,2021 Alexander Peslyak
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -65,7 +65,11 @@ static const uint32_t Krnd[64] = {
/* Elementary functions used by SHA256 */
#define Ch(x, y, z) ((x & (y ^ z)) ^ z)
-#define Maj(x, y, z) ((x & (y | z)) | (y & z))
+#if 1 /* Explicit caching/reuse of common subexpression between rounds */
+#define Maj(x, y, z) (y ^ ((x_xor_y = x ^ y) & y_xor_z))
+#else /* Let the compiler cache/reuse or not */
+#define Maj(x, y, z) (y ^ ((x ^ y) & (y ^ z)))
+#endif
#define SHR(x, n) (x >> n)
#define ROTR(x, n) ((x >> n) | (x << (32 - n)))
#define S0(x) (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
@@ -77,7 +81,8 @@ static const uint32_t Krnd[64] = {
#define RND(a, b, c, d, e, f, g, h, k) \
h += S1(e) + Ch(e, f, g) + k; \
d += h; \
- h += S0(a) + Maj(a, b, c);
+ h += S0(a) + Maj(a, b, c); \
+ y_xor_z = x_xor_y;
/* Adjusted round function for rotating state */
#define RNDr(S, W, i, ii) \
@@ -110,6 +115,7 @@ SHA256_Transform(uint32_t state[static restrict 8],
/* 3. Mix. */
for (i = 0; i <= 48; i += 16) {
+ uint32_t x_xor_y, y_xor_z = S[(65 - i) % 8] ^ S[(66 - i) % 8];
RNDr(S, W, 0, i);
RNDr(S, W, 1, i);
RNDr(S, W, 2, i);