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CRC32Digest produces differing values
From: |
M. Wied |
Subject: |
CRC32Digest produces differing values |
Date: |
Tue, 10 May 2005 10:37:30 -0000 |
User-agent: |
KMail/1.7.2 |
Hello everybody.
I've been using cc++ libraries without being aware of bugs for several
versions now, but needed the CRC32 computation recently.
Unfortuantely I got constantly values that differed form those of the other
project memebers. When investigating, I found in your corresponding source
file that an ethernet compliant CRC32-polynom was used.
I found a specification at
http://www.geocities.com/SiliconValley/Pines/8659/crc.htm by Ross N.
Williams
that stated values, that all other members of our group could reproduce, but
not cc++ :
--------------->
Here is the specification for the CRC-32 algorithm which is reportedly
used in PKZip, AUTODIN II, Ethernet, and FDDI.
Name : "CRC-32"
Width : 32
Poly : 04C11DB7
Init : FFFFFFFF
RefIn : True
RefOut : True
XorOut : FFFFFFFF
Check : CBF43926
-----------------<
Check means Checksum when digesting "123456789"
Though the specification states that this would be ethernet too, it differs
from cc++ results. I could reproduce the results of the expamle (AAL-5 - ATM)
with cc++ but the perl, java and other c implementations get different values
for these checks even though the poly you is the same as the one mentioned
above.
Any idea what the reason might be?
Thanx,
Markus
--
_____ _ _ _ __ ____ _ ______ _______
(____ \ (_) | | / ) / |/ __ \ | / __ (_______)
_ \ \ _ ____ | | / /_ _ /_/ ( (__) ) / | //| |______
| | | | |/ _ ) | |< <| | | || |\__ / /| |// | (_____ \
| |__/ /| ( (/ / _ | | \ \ | | || | / / / | /__| |_____) )
|_____/ |_|\____| ) |_| \_)____||_| /_/_| \_____/(______( )
|/ |/
______ _ __ ______ ______ _____ ______ ____
| ___ \ (_) / (_____ \ / __ |/ ___ \ / __ |/ __ \
| | _ | | ____ _ /_/ | ____) )_| | //| ( ( ) )| | //| ( (__) )
| || || |/ _ | | | |/_____/(_) |// | |> > < <_) |// | |\__ /
| || || ( ( | | |_ | |_______ _| /__| ( (___) )| /__| | / /
|_||_||_|\_||_|_( ) |_(_______|_)\_____/ \_____(_)\_____/ /_/
|/
______ _______ _ _______
/ _____|_______) | | (_______)
| / _____ \ \ _
| | | ___) \ \| |
| \_____| |_____ _____) ) |_____
\______)_______|______/ \______)
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