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From: David Gibson <david@gibson.dropbear.id.au>
To: Stefano Brivio <sbrivio@redhat.com>, passt-dev@passt.top
Cc: David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH v2 05/10] siphash: Fix bug in state initialisation
Date: Thu, 28 Sep 2023 11:20:57 +1000	[thread overview]
Message-ID: <20230928012102.1446180-6-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20230928012102.1446180-1-david@gibson.dropbear.id.au>

The SipHash algorithm starts with initializing the 32 bytes of internal
state with some magic numbers XORed with the hash key.  However, our
implementation has a bug - rather than XORing the hash key, it *sets* the
initial state to copies of the key.

I don't know if that affects any of the cryptographic properties of SipHash
but it's not what we should be doing.  Fix it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 siphash.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/siphash.c b/siphash.c
index ec39793..6932da2 100644
--- a/siphash.c
+++ b/siphash.c
@@ -65,7 +65,7 @@
 									  \
 	do {								  \
 		for (__i = sizeof(v) / sizeof(v[0]) - 1; __i >= 0; __i--) \
-			v[__i] = k[__i % 2];				  \
+			v[__i] ^= k[__i % 2];				  \
 	} while (0)
 
 /**
-- 
@@ -65,7 +65,7 @@
 									  \
 	do {								  \
 		for (__i = sizeof(v) / sizeof(v[0]) - 1; __i >= 0; __i--) \
-			v[__i] = k[__i % 2];				  \
+			v[__i] ^= k[__i % 2];				  \
 	} while (0)
 
 /**
-- 
2.41.0


  parent reply	other threads:[~2023-09-28  1:21 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-28  1:20 [PATCH v2 00/10] siphash: cleanups and fixes David Gibson
2023-09-28  1:20 ` [PATCH v2 01/10] siphash: Make siphash functions consistently return 64-bit results David Gibson
2023-09-28  1:20 ` [PATCH v2 02/10] siphash: Make sip round calculations an inline function rather than macro David Gibson
2023-09-28  1:20 ` [PATCH v2 03/10] siphash: Add siphash_feed() helper David Gibson
2023-09-28  1:20 ` [PATCH v2 04/10] siphash: Clean up hash finalisation with posthash_final() function David Gibson
2023-09-28  1:20 ` David Gibson [this message]
2023-09-28  1:20 ` [PATCH v2 06/10] siphash: Use more hygienic state initialiser David Gibson
2023-09-28  1:20 ` [PATCH v2 07/10] siphash: Use specific structure for internal state David Gibson
2023-09-28  1:21 ` [PATCH v2 08/10] siphash: Make internal helpers public David Gibson
2023-09-28  1:21 ` [PATCH v2 09/10] siphash, checksum: Move TBAA explanation to checksum.c David Gibson
2023-09-28  1:21 ` [PATCH v2 10/10] siphash: Use incremental rather than all-at-once siphash functions David Gibson
2023-09-30 10:43 ` [PATCH v2 00/10] siphash: cleanups and fixes Stefano Brivio

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