From: Bob I on 30 Nov 2009 11:34
Paul Randall wrote:
> "HeyBub" <heybub(a)gmail.com> wrote in message
>>>Files are compared using the checksum value.
>>>If CRC are equal, file contents must be equal/
>>Almost certainly that's true, but not always.
>>If the check-sum is four bytes, there's a one-in-four-quadrillion chance
>>the files could differ but have the same check-sum.
> Also, a malicious person could have modified the file in such a way that the
> CRC is the same as it was before the modification. Other checksum
> mechanism, such as MD5 were designed to be more difficult to spoof in this
> way, but it turned out to be not that much more difficult. To be really
> sure that the content of two files is identical, one might verify that the
> CRC, MD5, and SHA checksums are all identical for the two files.
> -Paul Randall
See FC with the /b switch in Windows Help.