The card on file feature is necessary for my business as a massage therapist, however the authorization form, as it is currently available from square, is illegal and I cannot use it.  

According to this, the card number cannot be written down in a readable form.  Is there an encrypted version of the card authorization form that we can use and follows the legal requirements for storing credit card information?  

PCI DSS Requirement 3.4

If storage of the PAN is unavoidable, this data must be made unreadable wherever it is stored.