svn commit: r202477 - stable/8/sys/opencrypto
Bjoern A. Zeeb
bz at FreeBSD.org
Sun Jan 17 13:36:14 UTC 2010
Author: bz
Date: Sun Jan 17 13:36:13 2010
New Revision: 202477
URL: http://svn.freebsd.org/changeset/base/202477
Log:
MFC r201898:
Add comments trying to explain what bad things happen here, i.e.
how hashed MD5/SHA are implemented, abusing Final() for padding and
sw_octx to transport the key from the beginning to the end.
Enlightened about what was going on here by: cperciva
Reviewed by: cperciva
Modified:
stable/8/sys/opencrypto/cryptosoft.c
Directory Properties:
stable/8/sys/ (props changed)
stable/8/sys/amd64/include/xen/ (props changed)
stable/8/sys/cddl/contrib/opensolaris/ (props changed)
stable/8/sys/contrib/dev/acpica/ (props changed)
stable/8/sys/contrib/pf/ (props changed)
stable/8/sys/dev/xen/xenpci/ (props changed)
Modified: stable/8/sys/opencrypto/cryptosoft.c
==============================================================================
--- stable/8/sys/opencrypto/cryptosoft.c Sun Jan 17 13:32:14 2010 (r202476)
+++ stable/8/sys/opencrypto/cryptosoft.c Sun Jan 17 13:36:13 2010 (r202477)
@@ -434,7 +434,16 @@ swcr_authprepare(struct auth_hash *axf,
case CRYPTO_MD5_KPDK:
case CRYPTO_SHA1_KPDK:
{
- /* We need a buffer that can hold an md5 and a sha1 result. */
+ /*
+ * We need a buffer that can hold an md5 and a sha1 result
+ * just to throw it away.
+ * What we do here is the initial part of:
+ * ALGO( key, keyfill, .. )
+ * adding the key to sw_ictx and abusing Final() to get the
+ * "keyfill" padding.
+ * In addition we abuse the sw_octx to save the key to have
+ * it to be able to append it at the end in swcr_authcompute().
+ */
u_char buf[SHA1_RESULTLEN];
sw->sw_klen = klen;
@@ -495,9 +504,17 @@ swcr_authcompute(struct cryptodesc *crd,
case CRYPTO_MD5_KPDK:
case CRYPTO_SHA1_KPDK:
+ /* If we have no key saved, return error. */
if (sw->sw_octx == NULL)
return EINVAL;
+ /*
+ * Add the trailing copy of the key (see comment in
+ * swcr_authprepare()) after the data:
+ * ALGO( .., key, algofill )
+ * and let Final() do the proper, natural "algofill"
+ * padding.
+ */
axf->Update(&ctx, sw->sw_octx, sw->sw_klen);
axf->Final(aalg, &ctx);
break;
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