The Clinical Document Architecture (CDA) introduced by Health Level Seven (HL7) is a XML-based standard intended to specify the encoding, structure and semantics of clinical documents for exchange. Since the clinical document is in XML form, its authenticity and integrity could be guaranteed by means of using XML Signature (XMLDsig) published by W3C. But in some cases, like the medical document de-identification for research use, we encountered the digital document sanitizing problem. This thesis investigates the use of redactable signatures in clinical documents and tries to find a solution when dealing with implementing redactable signatures in CDA.