Create a detached signature using a HMAC key

In the example, an XML document ("MyDocument.xml") is loaded and signed with a HMAC key.

You can use the sample content provided in XML document (unsigned) for the purpose of testing the code. Copy the content to a file named "MyDocument.xml" in a directory where you test the sample code.

IMPORT xml

MAIN
  DEFINE doc xml.DomDocument
  DEFINE sig xml.Signature
  DEFINE key xml.CryptoKey
  DEFINE index INTEGER
  # Create DomDocument object
  LET doc = xml.DomDocument.Create()
  # Notice that whitespaces are significant in cryptography, 
  # therefore it is recommended that you remove unnecessary ones 
  CALL doc.setFeature("whitespace-in-element-content",FALSE)
  TRY
    # Load document to be signed
    CALL doc.load("MyDocument.xml")
    # Create HMAC key
    LET key = xml.CryptoKey.Create("http://www.w3.org/2000/09/xmldsig#hmac-sha1")
    CALL key.setKey("secretpassword")
     # Create signature object with the key to use
    LET sig = xml.Signature.Create()
    CALL sig.setKey(key)
    # Set XML node to be signed. In our case, the node with attribute
    # 'xml:id="code"'
    LET index = sig.createReference("#code",
      "http://www.w3.org/2000/09/xmldsig#sha1")
    # Set canonicalization method on the XML fragment to be signed.
    CALL sig.appendReferenceTransformation(index,
      "http://www.w3.org/2001/10/xml-exc-c14n#")
    # Compute detached signature
    CALL sig.compute(doc)
    # Retrieve signature document
    LET doc=sig.getDocument()
    # Save signature on disk
    CALL doc.setFeature("format-pretty-print",TRUE)
    CALL doc.save("MyDocumentDetachedSignature.xml")
  CATCH
    DISPLAY "Unable to create a detached signature :",status
  END TRY
END MAIN