Hi,
The commoncryptolib uses x.509 certificates, so you wouldn't be able to use this unless you distribute certificates to each workstation and maintain these when they expire. If you already have a PKI in your company, then this might work for you. The SNC Client Encryption library is free and uses Kerberos tickets to generate encryption keys, which are used to encrypt the DIAG protocol communications. If however you don't have and cannot setup trust between domains, then this library won't work for you. So, your can't do what you want for free.
Thanks
Tim