From: Matt Mackall <mpm@selenic.com>
A replacement SHA routine that's slightly larger, but over twice as
fast. It's also faster and much smaller than the cryptolib version.
size speed buffer size
original: 350B 2.3us 320B
cryptolib: 5776B 1.2us 80B
this code: 466B 1.0us 320B
alternate: 2112B 1.0us 80B
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/lib/sha1.c | 104 ++++++++++++++++++++++++-----------------------------
1 files changed, 49 insertions(+), 55 deletions(-)
diff -puN lib/sha1.c~random-pt4-replace-sha-with-faster-version lib/sha1.c
--- 25/lib/sha1.c~random-pt4-replace-sha-with-faster-version 2005-02-23 02:15:25.000000000 -0800
+++ 25-akpm/lib/sha1.c 2005-02-23 02:15:42.000000000 -0800
@@ -1,18 +1,17 @@
/*
- * SHA transform algorithm, taken from code written by Peter Gutmann,
- * and placed in the public domain.
+ * SHA transform algorithm, originally taken from code written by
+ * Peter Gutmann, and placed in the public domain.
*/
#include <linux/kernel.h>
-#include <linux/string.h>
+#include <linux/module.h>
#include <linux/cryptohash.h>
/* The SHA f()-functions. */
-#define f1(x,y,z) (z ^ (x & (y ^ z))) /* Rounds 0-19: x ? y : z */
-#define f2(x,y,z) (x ^ y ^ z) /* Rounds 20-39: XOR */
-#define f3(x,y,z) ((x & y) + (z & (x ^ y))) /* Rounds 40-59: majority */
-#define f4(x,y,z) (x ^ y ^ z) /* Rounds 60-79: XOR */
+#define f1(x,y,z) (z ^ (x & (y ^ z))) /* x ? y : z */
+#define f2(x,y,z) (x ^ y ^ z) /* XOR */
+#define f3(x,y,z) ((x & y) + (z & (x ^ y))) /* majority */
/* The SHA Mysterious Constants */
@@ -26,65 +25,60 @@
*
* @digest: 160 bit digest to update
* @data: 512 bits of data to hash
- * @W: 80 words of workspace
+ * @W: 80 words of workspace (see note)
*
- * This function generates a SHA1 digest for a single. Be warned, it
- * does not handle padding and message digest, do not confuse it with
- * the full FIPS 180-1 digest algorithm for variable length messages.
+ * This function generates a SHA1 digest for a single 512-bit block.
+ * Be warned, it does not handle padding and message digest, do not
+ * confuse it with the full FIPS 180-1 digest algorithm for variable
+ * length messages.
+ *
+ * Note: If the hash is security sensitive, the caller should be sure
+ * to clear the workspace. This is left to the caller to avoid
+ * unnecessary clears between chained hashing operations.
*/
-void sha_transform(__u32 *digest, const char *data, __u32 *W)
+void sha_transform(__u32 *digest, const char *in, __u32 *W)
{
- __u32 A, B, C, D, E;
- __u32 TEMP;
- int i;
+ __u32 a, b, c, d, e, t, i;
- memset(W, 0, sizeof(W));
for (i = 0; i < 16; i++)
- W[i] = be32_to_cpu(((const __u32 *)data)[i]);
- /*
- * Do the preliminary expansion of 16 to 80 words. Doing it
- * out-of-line line this is faster than doing it in-line on
- * register-starved machines like the x86, and not really any
- * slower on real processors.
- */
- for (i = 0; i < 64; i++) {
- TEMP = W[i] ^ W[i+2] ^ W[i+8] ^ W[i+13];
- W[i+16] = rol32(TEMP, 1);
+ W[i] = be32_to_cpu(((const __u32 *)in)[i]);
+
+ for (i = 0; i < 64; i++)
+ W[i+16] = rol32(W[i+13] ^ W[i+8] ^ W[i+2] ^ W[i], 1);
+
+ a = digest[0];
+ b = digest[1];
+ c = digest[2];
+ d = digest[3];
+ e = digest[4];
+
+ for (i = 0; i < 20; i++) {
+ t = f1(b, c, d) + K1 + rol32(a, 5) + e + W[i];
+ e = d; d = c; c = rol32(b, 30); b = a; a = t;
}
- /* Set up first buffer and local data buffer */
- A = digest[ 0 ];
- B = digest[ 1 ];
- C = digest[ 2 ];
- D = digest[ 3 ];
- E = digest[ 4 ];
-
- /* Heavy mangling, in 4 sub-rounds of 20 iterations each. */
- for (i = 0; i < 80; i++) {
- if (i < 40) {
- if (i < 20)
- TEMP = f1(B, C, D) + K1;
- else
- TEMP = f2(B, C, D) + K2;
- } else {
- if (i < 60)
- TEMP = f3(B, C, D) + K3;
- else
- TEMP = f4(B, C, D) + K4;
- }
- TEMP += rol32(A, 5) + E + W[i];
- E = D; D = C; C = rol32(B, 30); B = A; A = TEMP;
+ for (; i < 40; i ++) {
+ t = f2(b, c, d) + K2 + rol32(a, 5) + e + W[i];
+ e = d; d = c; c = rol32(b, 30); b = a; a = t;
}
- /* Build message digest */
- digest[0] += A;
- digest[1] += B;
- digest[2] += C;
- digest[3] += D;
- digest[4] += E;
+ for (; i < 60; i ++) {
+ t = f3(b, c, d) + K3 + rol32(a, 5) + e + W[i];
+ e = d; d = c; c = rol32(b, 30); b = a; a = t;
+ }
+
+ for (; i < 80; i ++) {
+ t = f2(b, c, d) + K4 + rol32(a, 5) + e + W[i];
+ e = d; d = c; c = rol32(b, 30); b = a; a = t;
+ }
- /* W is wiped by the caller */
+ digest[0] += a;
+ digest[1] += b;
+ digest[2] += c;
+ digest[3] += d;
+ digest[4] += e;
}
+EXPORT_SYMBOL(sha_transform);
/*
* sha_init: initialize the vectors for a SHA1 digest
_