From: Dr. Stephen Henson <steve@openssl.org>
Date: Sun, 14 Oct 2012 12:26:02 +0000 (+0000)
Subject: optimize make_kn (from HEAD, by Andy)
X-Git-Tag: OpenSSL-fips-2_0-pl1~7
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=82607b291f2e1ebf31fde8956b9d6cfbee060d30;p=oweals%2Fopenssl.git

optimize make_kn (from HEAD, by Andy)
---

diff --git a/crypto/cmac/cmac.c b/crypto/cmac/cmac.c
index ccc7e7a3bd..5ff0fa7028 100644
--- a/crypto/cmac/cmac.c
+++ b/crypto/cmac/cmac.c
@@ -77,19 +77,17 @@ struct CMAC_CTX_st
 
 /* Make temporary keys K1 and K2 */
 
-static void make_kn(unsigned char *k1, unsigned char *l, int bl)
+static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
 	{
 	int i;
+	unsigned char c = l[0], carry = c>>7, cnext;
+
 	/* Shift block to left, including carry */
-	for (i = 0; i < bl; i++)
-		{
-		k1[i] = l[i] << 1;
-		if (i < bl - 1 && l[i + 1] & 0x80)
-			k1[i] |= 1;
-		}
+	for (i = 0; i < bl-1; i++, c = cnext)
+		k1[i] = (c << 1) | ((cnext=l[i+1]) >> 7);
+
 	/* If MSB set fixup with R */
-	if (l[0] & 0x80)
-		k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b;
+	k1[i] = (c << 1) ^ ((0-carry)&(bl==16?0x87:0x1b));
 	}
 
 CMAC_CTX *CMAC_CTX_new(void)