GDPR compatible data handling

[ineiti]

For the privacy policy of C4DT, use calypso to handle private data:

• store all sensitive data calypso-encrypted
• give access through DARCs
• every Write-access must have a 'reason' added
• when the resource is destroyed, all write-accesses must be 'neutralized' and confirm that they did delete the data

In the best case, this would be developed together with https://github.com/ineiti/cybermind

Depends on #212