Ascend Archive
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Re: (ASCEND) Firmware upgrade ??

On Mon, Jan 26, 1998 at 07:49:09PM -0400, Tim Basher wrote:
> > I've suggested several times that Ascend supply a md5sum text file of the
> > qualities of the images, That way you can compare and see if the image you
> > got was the same image on the FTP site.
> 
> Ascend *does* supply a checksum of each release image on the FTP site.
> the value provided is the 16-bit CRC checksum calculated using the
> UNIX "sum" or "cksum" program.  A 16-bit CRC is quite sufficient to
> detect transmission errors of a one megabyte file.

I've tried these checksums once and they didn't match, neither one nor
the other. Anyway the image was Ok. I instantly forgot about this feature.
Let's try today:

beck@micky:~ > uname -a
SunOS micky 5.5 Generic_103093-10 sun4m sparc SUNW,SPARCstation-5
beck@micky:~ > where sum
/usr/ucb/sum
/bin/sum
/usr/bin/sum
beck@micky:~ > /usr/ucb/sum /var/tftp/b.p50_5.1A_p6 
06530   441
beck@micky:~ > /bin/sum /var/tftp/b.p50_5.1A_p6
53420 882 /var/tftp/b.p50_5.1A_p6

Hu. Ahhm. Great. At least:

CHECKSUMS:
---------
(SunOS 5.5.1)

% sum *.*

[...]
53420 882 b.p50
[...]

Ok, they use the native sum. But seeing the above I'm pretty sure you
get similar problems on other platforms. md5sum however ist _strictly_
defined and you can even verify a whole directory tree against a sum
file in a single command. It is more reliable compared to sum (maybe a
16 bit sum is enough for a 1 MB file, but this sum likely computes
the same value if you swap bytes - not that good IMHO).

Lets see:

beck@micky:~ > dd if=/var/tftp/b.p50_5.1A_p6 of=foo conv=swab
881+1 records in
881+1 records out
beck@micky:~ > /usr/bin/sum foo
53420 882 foo

Real great check that.

> Versions of "sum" are available for MS-DOS, MS-WIN, and MAC systems.

md5sum is available as source as well. Best would be to supply a file
with MD5 sums for the whole release and a signature of this file itself
so its authenticy can be verified.

-- 

Kanther-Line: PGP SSH IDEA MD5 GOST RIPE-MD160 3DES RSA FEAL32 RC4

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| o |               \\\- Brain Inside -///                   | o |
| o |                   ^^^^^^^^^^^^^^                       | o |
| o | Andre' Beck (ABPSoft) beck@ibh-dd.de XLink PoP Dresden | o |
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