It is based on the openssl extensions of PHP. It can generate DKIM signature but cannot verify them. Php-dkim supports RSA signature and SHA-1 hash for DKIM. The relaxed header canonicalization is supported (only simple body canonicalization).
Php-dkim allows any PHP application to send email with a DKIM signature this should decrease the probability of getting this email tagged as spam.
Developped and tested on PHP 4.0 (should also work on PHP 5 and higher of course).
Further DKIM information is available at www.dkim.org.
Access the source code at the CVS repository: http://php-dkim.cvs.sourceforge.net/php-dkim/.
Download the package (PHP & doc file).