Provenance with signature for a Consent

{
  "resourceType" : "Provenance",
  "id" : "consent-signature",
  "target" : [{
    "reference" : "Consent/consent-example-basic/_history/1"
  }],
  "recorded" : "2016-05-26T00:41:10-04:00",
  "activity" : {
    "coding" : [{
      "system" : "http://terminology.hl7.org/CodeSystem/v3-DocumentCompletion",
      "code" : "AU",
      "display" : "authenticated"
    }]
  },
  "patient" : {
    "reference" : "Patient/example"
  },
  "agent" : [{
    "role" : [{
      "coding" : [{
        "system" : "http://terminology.hl7.org/CodeSystem/v3-ParticipationType",
        "code" : "AUT"
      }]
    }],
    "who" : {
      "reference" : "Patient/72"
    }
  }],
  "signature" : [{
    "type" : [{
      "system" : "urn:iso-astm:E1762-95:2013",
      "code" : "1.2.840.10065.1.12.1.1",
      "display" : "Author's Signature"
    }],
    "when" : "2016-05-26T00:41:10-04:00",
    "who" : {
      "reference" : "Patient/72"
    },
    "targetFormat" : "application/fhir+xml",
    "sigFormat" : "application/signature+xml",
    "data" : "dGhpcyBibG9iIGlzIHNuaXBwZWQ="
  }]
}