Create an enveloping signature using a DSA key

IMPORT xml

MAIN
  DEFINE doc xml.DomDocument
  DEFINE sig xml.Signature
  DEFINE key xml.CryptoKey
  DEFINE index INTEGER
  DEFINE objInd INTEGER
  # Create DomDocument object
  LET doc = xml.DomDocument.Create()
  # Notice that whitespaces are significant in cryptography, 
  # therefore it is recommended to remove unnecessary ones 
  CALL doc.setFeature("whitespace-in-element-content",FALSE)
  TRY
    # Load document to be signed
    CALL doc.load("MyDocument.xml")
    # Create DSA key and load it from file
    LET key = xml.CryptoKey.Create(
      "http://www.w3.org/2000/09/xmldsig#dsa-sha1")
    CALL key.loadPEM("DSAKey.pem")
    # Create signature object with the key to use
    LET sig = xml.Signature.Create()
    CALL sig.setKey(key)
    # Create an object inside the signature to envelop the root node 
    LET objInd = sig.createObject()
    # Set the object id to get a reference
    CALL sig.setObjectId(objInd,"data")
    # Copy the enveloping node from the document
    CALL sig.appendObjectData(objInd,doc.getDocumentElement())
    # Set the reference to be signed on the object node. 
    # In our case, the object node with attribute 'data'
    LET index = sig.createReference("#data",
      "http://www.w3.org/2000/09/xmldsig#sha1")
    # Set canonicalization method on the enveloping object to be signed.
    CALL sig.appendReferenceTransformation(index,
      "http://www.w3.org/2001/10/xml-exc-c14n#")
    # Compute enveloping signature
    CALL sig.compute(NULL)
    # Retrieve signature document
    LET doc=sig.getDocument()
    # Save signature on disk
    CALL doc.setFeature("format-pretty-print",TRUE)
    CALL doc.save("MyDocumentEnvelopingSignature.xml")
  CATCH
    DISPLAY "Unable to create an enveloping signature :",STATUS
  END TRY
END MAIN