libgcrypt/cipher (ChangeLog cipher.c)

[cvs user mo]

    Date: Saturday, March 19, 2005 @ 18:35:27
  Author: mo
    Path: /cvs/libgcrypt/libgcrypt/cipher

Modified: ChangeLog cipher.c

2005-03-19  Moritz Schulte  <moritz at g10code.com>

	* cipher.c (do_cbc_encrypt): Be careful to not overwrite data,
	which is to be used later on.  This happend, in case CTS is
	enabled and OUTBUF is equal to INBUF.


-----------+
 ChangeLog |    6 ++++++
 cipher.c  |   28 +++++++++++++++++-----------
 2 files changed, 23 insertions(+), 11 deletions(-)


Index: libgcrypt/cipher/ChangeLog
diff -u libgcrypt/cipher/ChangeLog:1.225 libgcrypt/cipher/ChangeLog:1.226
--- libgcrypt/cipher/ChangeLog:1.225	Fri Feb 25 11:48:10 2005
+++ libgcrypt/cipher/ChangeLog	Sat Mar 19 18:35:27 2005
@@ -1,3 +1,9 @@
+2005-03-19  Moritz Schulte  <moritz at g10code.com>
+
+	* cipher.c (do_cbc_encrypt): Be careful to not overwrite data,
+	which is to be used later on.  This happend, in case CTS is
+	enabled and OUTBUF is equal to INBUF.
+
 2005-02-25  Werner Koch  <wk at g10code.com>
 
 	* pubkey.c (gcry_pk_get_keygrip): Allow for shadowed-private-key.
Index: libgcrypt/cipher/cipher.c
diff -u libgcrypt/cipher/cipher.c:1.70 libgcrypt/cipher/cipher.c:1.71
--- libgcrypt/cipher/cipher.c:1.70	Mon Aug 23 15:33:15 2004
+++ libgcrypt/cipher/cipher.c	Sat Mar 19 18:35:27 2005
@@ -784,30 +784,36 @@
 	    outbuf[i] = inbuf[i] ^ *ivp++;
 	c->cipher->encrypt ( &c->context.c, outbuf, outbuf );
 	memcpy(c->iv, outbuf, blocksize );
-	inbuf  += c->cipher->blocksize;
+	inbuf  += blocksize;
 	if (!(c->flags & GCRY_CIPHER_CBC_MAC))
-	  outbuf += c->cipher->blocksize;
+	  outbuf += blocksize;
     }
 
     if ((c->flags & GCRY_CIPHER_CBC_CTS) && nbytes > blocksize)
       {
+	/* We have to be careful here, since outbuf might be equal to
+	   inbuf.  */
+
 	int restbytes;
+	byte b;
 
 	if ((nbytes % blocksize) == 0)
 	  restbytes = blocksize;
 	else
 	  restbytes = nbytes % blocksize;
 
-	memcpy(outbuf, outbuf - c->cipher->blocksize, restbytes);
-	outbuf -= c->cipher->blocksize;
-
-	for(ivp=c->iv,i=0; i < restbytes; i++ )
-	    outbuf[i] = inbuf[i] ^ *ivp++;
-	for(; i < blocksize; i++ )
-	    outbuf[i] = 0 ^ *ivp++;
+	outbuf -= blocksize;
+	for (ivp = c->iv, i = 0; i < restbytes; i++)
+	  {
+	    b = inbuf[i];
+	    outbuf[blocksize + i] = outbuf[i];
+	    outbuf[i] = b ^ *ivp++;
+	  }
+	for (; i < blocksize; i++)
+	  outbuf[i] = 0 ^ *ivp++;
 
-	c->cipher->encrypt ( &c->context.c, outbuf, outbuf );
-	memcpy(c->iv, outbuf, blocksize );
+	c->cipher->encrypt (&c->context.c, outbuf, outbuf);
+	memcpy (c->iv, outbuf, blocksize);
       }
 }