From 121005001a8bbf3bd4d0ae74de93e449f27624ec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se>
Date: Tue, 24 Aug 2004 20:36:16 +0200
Subject: [PATCH] (des_cbc_cksum): Pad input with NUL:s, if it's not an
integral number of blocks.
Rev: src/nettle/des-compat.c:1.15
---
des-compat.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/des-compat.c b/des-compat.c
index 5c0bf3f3..1b8ae914 100644
--- a/des-compat.c
+++ b/des-compat.c
@@ -71,6 +71,10 @@ des_ecb3_encrypt(const_des_cblock *src, des_cblock *dst,
(&keys, DES_BLOCK_SIZE, *dst, *src);
}
+/* If input is not a integral number of blocks, the final block is
+ padded with zeros, no length field or anything like that. That's
+ pretty broken, since it means that "$100" and "$100\0" always have
+ the same checksum, but I think that's how it's supposed to work. */
uint32_t
des_cbc_cksum(const uint8_t *src, des_cblock *dst,
long length, des_key_schedule ctx,
@@ -80,16 +84,21 @@ des_cbc_cksum(const uint8_t *src, des_cblock *dst,
* work, in particular what it should return, and if iv can be
* modified. */
uint8_t block[DES_BLOCK_SIZE];
- const uint8_t *p;
memcpy(block, *iv, DES_BLOCK_SIZE);
-
- assert(!(length % DES_BLOCK_SIZE));
-
- for (p = src; length; length -= DES_BLOCK_SIZE, p += DES_BLOCK_SIZE)
+
+ while (length >= DES_BLOCK_SIZE)
{
- memxor(block, p, DES_BLOCK_SIZE);
+ memxor(block, src, DES_BLOCK_SIZE);
nettle_des_encrypt(ctx, DES_BLOCK_SIZE, block, block);
+
+ src += DES_BLOCK_SIZE;
+ length -= DES_BLOCK_SIZE;
+ }
+ if (length > 0)
+ {
+ memxor(block, src, length);
+ nettle_des_encrypt(ctx, DES_BLOCK_SIZE, block, block);
}
memcpy(*dst, block, DES_BLOCK_SIZE);
--
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