sql server - CHECKSUM and CHECKSUM_AGG: What's the algorithm?

Question

We perform checksums of some data in sql server as follows:

declare @cs int;
select 
    @cs = CHECKSUM_AGG(CHECKSUM(someid, position))
from 
    SomeTable
where 
    userid = @userId
group by 
    userid;

This data is then shared with clients. We'd like to be able to repeat the checksum at the client end... however there doesn't seem to be any info about how the checksums in the functions above are calculated. Can anyone enlighten me?

Answer 1

On SQL Server Forum, at this page, it's stated:

The built-in CHECKSUM function in SQL Server is built on a series of 4 bit left rotational xor operations. See this post for more explanation.