[wp-hackers] Another method for anti comment spam

[Moi]

Hi all,
The last week my wp was victime of many spam on comment. I have tried
wpblacklist but this plugin can't give me all satisfaction.
So I try to add a complementary checking into comment form basing on
"human authentication" (yep if I could call that :)). There are steps
which I done:

1. Turn on session for WP
2. Write a small & simple function to generate a random string by using rand()
3. In comment form, call this function to get a random string. Save
this string into session. Use GD image functions to create an image
on-the-fly from random string and display it on comment form.
4. In submit, check if the submitted string of user is matched over
random string saved in session. If not exit().

Any comments for this method ?
Cheers,

Q. NGUYEN DAI
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