Checksum

[Rain]

hi,

need help here, does anyone know how to use or does any one have the code
for checksum? I want to checksum a string to be sent using udp and checksum
it again when received.. does anyone know the code for checksum? Thanks i
would really really appreciate it. Thanks in advance..

[KH]

I'm assuming you mean the CHECKSUM function in SQL server; if not disregard.

Anyways ... no, no one has the code for CHICKSUM. Well the SQL Server team
must, but you shouldn't rely on it anyways - a hash function like CHECKSUM or
..NET's GetHashCode() can change from version to version so you shouldn't rely
on it.

What you should do is use a well known hash algorithym like MD5 or SHA1, and
use that for your comparisons. See the System.Security.Cryptography namespace
in .NET SDK.
"Rain" wrote:

hi,

need help here, does anyone know how to use or does any one have the code
for checksum? I want to checksum a string to be sent using udp and checksum
it again when received.. does anyone know the code for checksum? Thanks i
would really really appreciate it. Thanks in advance..

[Truong Hong Thi]

The easiest way is use Hash functions like MD5, SHA1.
Check out them in System.Security.Cryptography namespace.
Note that MD5 generates a byte array of 128 bytes (SHA1, 160 bytes).
You can convert them to hex string if needed.

Rain wrote:

hi,

need help here, does anyone know how to use or does any one have the code
for checksum? I want to checksum a string to be sent using udp and checksum
it again when received.. does anyone know the code for checksum? Thanks i
would really really appreciate it. Thanks in advance..

[Truong Hong Thi]

I mean bits, not bytes. And someone else already answered above, did
not notice.

Truong Hong Thi wrote:

The easiest way is use Hash functions like MD5, SHA1.
Check out them in System.Security.Cryptography namespace.
Note that MD5 generates a byte array of 128 bytes (SHA1, 160 bytes).
You can convert them to hex string if needed.

Rain wrote:

hi,

need help here, does anyone know how to use or does any one have the code
for checksum? I want to checksum a string to be sent using udp and checksum
it again when received.. does anyone know the code for checksum? Thanks i
would really really appreciate it. Thanks in advance..

[Tom Spink]

Rain wrote:

hi,

need help here, does anyone know how to use or does any one have the code
for checksum? I want to checksum a string to be sent using udp and
checksum it again when received.. does anyone know the code for checksum?
Thanks i would really really appreciate it. Thanks in advance..

Hi,

There are a number of checksum functions available, each with their merits
(and their disadvantages). Hashing (as has been mentioned) is a popular
method of creating a checksum, but there are also algorithms such as CRC -
the Cyclic Redundancy Check.

For your reference, here is an URL to an implementation of CRC:
http://www.codeproject.com/csharp/marcelcrcencoding.asp

--
Hope this helps,
Tom Spink

Google first, ask later.