Re: File Encryption: CBC vs ECB+IV modes

From: DSCOTT (daVvid_a_scott@email.com)
Date: 02/04/03 

From: daVvid_a_scott@email.com (DSCOTT)
Date: 4 Feb 2003 15:28:34 GMT

ukoganti@yahoo.com (Sudheer Koganti) wrote in
<e700e1e3.0302032130.4d674f43@posting.google.com>:

>
>Suppose a file needed to be encrypted and random accesses and frequent
>writes are common and are a critical design criteria. Furthermore,
>lets assume a block cipher is being used. One could choose various
>modes, but the simplest choice is the ECB mode. To make sure, two
>blocks in different files won't encrypt to the same cipher text, an IV
>can be used to XOR the plain text before encrypting. Lets call this
>ECB+IV mode.
>
>

  Are you saying the IV use for first block in ECB or all blocks?
If all blocks does the IV change for each block. If not then
two blocks haveing the same input data they will encrypt exactly the
same.

David A. Scott 

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