Hello everyone. I have a web service that can (also) email documents to clients. I want to be able to digitally sign documents in order to email them signed as proof of correct content. I am looking for a way to sign these documents. The documents are currently in HTML format but may be converted to PDF / DOC format in the future. The web service is written in PHP and i have access to shell, so i figure either there's a way to sign files with PHP, or I have to run system() command with php and sign as if I am signing from shell. Everything is on Debian Etch, Apache and MySQL. Can anyone help? Thanks.