Re: CRC32 on ELF in C problem

From: Randy Howard (randyhoward_at_FOOverizonBAR.net)
Date: 07/27/04 

Date: Mon, 26 Jul 2004 23:08:25 GMT

In article <8ac337d1.0407260654.1b230dfd@posting.google.com>, kevin@netkev.com
says...
> I need to calculate the checksum of certain sections in an ELF binary
> file. I'm able to parse through to the program header table and then
> find the section header table and then find the correct sections using
> the section header string table. Using this method, I am able to find
> the
> offset to the .text section and the number of bytes for the range of
> sections i need to calculate the checksum for.

Others have already pointed out in c.l.c and here various things about
your code. I wanted to bring up a slightly different matter, namely
that a 32-bit CRC is not necessarily guaranteed to be useful for
verifying that a program has not been modified, particularly if the
binary is quite large. There are better methods by far, especially
for larger files, which have much less likelihood of false positives
with multi-bit/byte corruptions.

Examples include md5 and sha-1, for example, which have far better
ability to detect corruption than CRC-32 or its brethren. 

-- 
Randy Howard
To reply, remove FOOBAR.

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