(in case there's a solution I couldn't envision)
I want to build a secure backup solution. As I own a smartcard, I thought to use asymmetric encryption with the private key remaining on the card for proper security. This would mean to use duplicati, which supports GPG based encryption out of the box and thereby I can "hack" myself asymmetrically encrypted backups together. The only problem remaining is, that my smart card doesn't implement the OpenPGP card standard (only CSP and PKCS#11 via OpenSC) and thereby I need an external tool to restore the files.
The resulting software requirements
- Must run on Windows (10)
- Must be able to parse and decrypt OpenPGP encrypted files
- Must work with a CSP / PKCS#11 enabled smartcard
- Must offer command-line based decryption
- May rely on other software (such as PuTTY-CAC)
- Should be free / open-source
The backup solution
I do have a Plan B, in case this goes wrong, which is to roll my own (really don't want that) and use Peter Gutmann's cryptlib to do the job.