FreeTSA - Guide: How to sign documents files with time stamp > Signing keys for PDF documentsTo digitally sign your PDF documents you need a private key!
Where do you get it? You have three options:
- Make your own key that others must take actions to trust it;
- Get a paid signing and/ or e-mail key from a company;
- Get a free e-mail certificate that can also sign the PDF files.
1) Create your own key.
If you don't know how to do it, please search for help in your favorite search engine.
- SecTools - http://sectools.free.fr/index-EN.htm (Free).
- OpenSSL - https://www.openssl.org - [This page may help] (Free).
- PFX Digital Certificate Generator https://www.signfiles.com - [Help files on the web site] (Free for personal use / Paid version for companies).
2) Get a paid signing key or e-mail signing key (normally can also be used to sign PDFs) from a company.
- See a complete list of certificate companies already included in Adobe PDF Reader products here.
3) Get a Free E-mail certificate.
Probably are not in the certification list of Adobe products, but users can verify that are real certificate authorities, and probably will trust those more easily.
- StartCom: https://www.startssl.com (Free).
- Comodo E-mail Certificate: https://www.comodo.com (Free for personal use).
- Actalis E-mail Certificate: https://www.actalis.it/products/certificates-for-secure-electronic-mail.aspx (Free for personal use).
- CAcert: http://www.cacert.org (Free - This certificate authority is not installed by default in most machines, but is very used by many persons around the world. To be certified, you may need to pay persons in your country to vouch for you).
Last update: October 7, 2015