Corrupt random bytes in rsync and/or ssh

I need to have the repeatable ability to corrupt random bytes of data transmitted via scp and rsync via ssh. It should only do this with the presence of a file (eg; /etc/corrupt), and it should be repeatable in the sense that subsequent rsyncs will have the same corruption. An example could be to XOR 8 bytes of data every 1k. I would like this to be patched for both OpenSSH and SSH2.