Re: Maybe we only need PCBC...

From: Andrew Swallow (am.swallow_at_eatspam.btinternet.com)
Date: 06/30/03 

Date: Mon, 30 Jun 2003 14:45:05 +0000 (UTC)

<jsavard@ecn.ab.ca> wrote in message news:W4PLa.911$Fy1.51795@localhost...
> Andrew Swallow (am.swallow@eatspam.btinternet.com) wrote:
> : CRC checksums are designed to handle low to medium error rates
> : generated by natural causes. Encrypting both the packet and the
> : checksum makes successfully performing undetected changes to
> : message difficult providing the CRCs location is also hidden.
>
> : A factor to remember is that total corruption of the message can
> : fool the CRC checker. CRC16 will pass 1 out of every 65,536
> : incorrect packets on a high error link. CRC32 can survive
> : 4,294,967,296 incorrect packets.
>
> Of course, with a block cipher with a 128-bit block size, a CRC-128
> checksum is being proposed.
>
A very high overhead on individual packets but should be OK
over a long message.

Andrew Swallow