21 C.F.R. § 203.60
(a) Use of electronic records, electronic signatures, and handwritten signatures executed to electronic records.
(2) Combinations of paper records and electronic records, electronic records and handwritten signatures executed on paper, or paper records and electronic signatures or handwritten signatures executed to electronic records, may be used to meet any of the record and signature requirements of PDMA, PDA, or this part, provided that:
(c) Security and authentication requirements for request and receipt forms, reports, records, and other documents created on paper. A request or receipt form, report, record, or other document, and any signature appearing thereon, that is created on paper and that is maintained by photographic imaging, or transmitted electronically (i.e., by facsimile) shall be maintained or transmitted in a form that provides reasonable assurance of being: