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Create XML Digital Signature using a DSA Key

See more XML Digital Signatures Examples

Demonstrates how to create an XML digital signature using a DSA key.

This example requires Chilkat v9.5.0.69 or greater.

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Local $bSuccess = False

; This example requires the Chilkat API to have been previously unlocked.
; See Global Unlock Sample for sample code.

; The XML to be signed in this example contains the following:

; <?xml version="1.0" encoding="UTF-8" standalone="no"?>
; <Envelope>
;   <Header>
;     <Security>
;     </Security>
;   </Header>
;   <Body Id="abc">
;     <z:FooBar xmlns:z="https://www.example-code.com"/>
;   </Body>
; </Envelope>

; The above XML is available at https://www.chilkatsoft.com/exampleData/xmlToSign.xml
; Fetch the XML and then sign it..

Local $sUrl = "https://www.chilkatsoft.com/exampleData/xmlToSign.xml"
$oHttp = ObjCreate("Chilkat.Http")
$oSbXml = ObjCreate("Chilkat.StringBuilder")
$bSuccess = $oHttp.QuickGetSb($sUrl,$oSbXml)
If ($bSuccess <> True) Then
    ConsoleWrite($oHttp.LastErrorText & @CRLF)
    Exit
EndIf

; This example uses a DSA private key for signing.  
; There are many ways of getting an DSA private key using Chilkat.  This example
; will load it from an encrypted PEM file.

; In case you would like to use it, I put the DSA private key PEM file here:
; https://www.chilkatsoft.com/exampleData/dsa1024_secret.zip
; The password is "secret".
$oDsaKey = ObjCreate("Chilkat.PrivateKey")
$bSuccess = $oDsaKey.LoadEncryptedPemFile("qa_data/dsa/dsa1024_secret.pem","secret")
If ($bSuccess <> True) Then
    ConsoleWrite($oDsaKey.LastErrorText & @CRLF)
    Exit
EndIf

; To create the XML digital signature (i.e. embed the signature within
; the XML), first specify what is desired, then call the method to 
; create the XML signature.
; 
; For example, the application must provide the following:
;     - Where to put the signature.
;     - What to sign.
;     - The algorithms to be used.
;     - The key to be used for signing.
; 

$oXmlSigGen = ObjCreate("Chilkat.XmlDSigGen")

; In this example, we're going to put the signature within the Security element.
; To specify the location, set the SigLocation property to the XML path to this element,
; using vertical bar characters to separate tags.
$oXmlSigGen.SigLocation = "Envelope|Header|Security"

; An XML digital signature contains one or more references.  These can be references to the parts
; of the XML document to be signed (a same document reference), or can be external references.
; This example will add a single same-document reference.  We'll add a reference to the XML fragment
; at Body, which is indicated by providing the value of the "ID" attribute (where "ID" is case
; insensitive).  In this case, we specify "abc" because Body has an Id="abc".
; This causes the <Body> ... </Body> XML fragment to be signed.
; 
; For each same-document reference, we must also indicate the hash algorithm and XML canonicalization
; algorithm to be used.  For this example we'll choose SHA1 and Exclusive XML Canonicalization.
$oXmlSigGen.AddSameDocRef("abc","sha1","EXCL_C14N","","")

; Provide the DSA key to be used for signing:
$oXmlSigGen.SetPrivateKey($oDsaKey)

; We're leaving the following properties at their default values:
; 
;    - SigNamespacePrefix (default is "ds")
;    - SignedInfoCanonAlg  (default is EXCL_C14N)
;    - KeyInfoType (default is "KeyValue", where the DSA public key is included in the Signature)

; Note: Each Reference has it's own specified algorithms for XML canonicalization and hashing,
; and the actual signature part (the SignedInfo) has it's own hash/canonicalization algorithm.
; They may or may not be the same.  In this example, we use Exclusive XML Canonicalization and SHA1 throughout.

; The default SignedInfoDigestMethod is sha256, which is a good choice.  This example will
; change it to sha1.
$oXmlSigGen.SignedInfoDigestMethod = "sha1"

; OK, everything's specified, so let's create the XML digital signature:
; This in-place signs the XML.  If successful, sbXml will contain the 
; XML with the digital signature at the specified location.
$bSuccess = $oXmlSigGen.CreateXmlDSigSb($oSbXml)
If ($bSuccess <> True) Then
    ConsoleWrite($oXmlSigGen.LastErrorText & @CRLF)
    Exit
EndIf

; Examine the signed XML:
ConsoleWrite($oSbXml.GetAsString() & @CRLF)

; Below is the signed XML that is produced.
; Chilkat emits the Signature in compact form on a single line.  Whitespace in XML signatures
; matters.  Chilkat's opinion is that writing the Signature without whitespace minimizes the chance
; for problems with whatever software might be verifying the signature.

; <?xml version="1.0" encoding="UTF-8" standalone="no"?>
; <Envelope>
;   <Header>
;     <Security>
;     <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"/><ds:Reference URI="#abc"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ds:DigestValue>77X3L6odxTBow1W1dIiqZW1foow=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>Ci/KiAqoQLvNyK94n8TJwdJ6dVpIIy8tJg+9s8utmB92cW8lTd+U7g==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:DSAKeyValue><ds:P>AN+Af9FvnqYl84Own8m/MHza9vVFEbpySOiWyeIM8diDjaES9i+UykaX9BGc0oaRJHtrHhe+gboMBGHfP+gYcgbqzeyVCi2kHghRD/TK7uI4jN8Yv8tfM6AO0QrDFfxFq4IV+qTZbSoCkbWaopQ+kEOY6B4btFxJ1YuE48mExMZ3</ds:P><ds:Q>AOCv5pwf4kvMW37Yzt0iH6URKOlD</ds:Q><ds:G>FO3eoDcpuU9Z25OQGFtC+M2ifczcKyRkFwTauGR3mIw0wePPiu3Ocr7A81SA8GQ9x3hWO5jyP//jL3jxYy8fgBg2RXwiic3nwT2rZfu50g6tPUpz1stKz/+Mxjulo6XuaMSOWwjU021IxVMzxQ1/L8QiwiIrwxvfQOaMY8HJgvw=</ds:G><ds:Y>JJmZQvWtrZ+Nb2YV47SfGAave8uOIedGlmg+CseoqKZC2aFcWM6kR0giUwQx834dhxQScRhqzxFxQPk/x+5hyG8LQbXW+BELmT1BiyodobYUAet4rSIt4EU4KU0iYw1drpcWT1jqI07l5xNi28heYSfSF5Odv2qwXxVKDSEeEkM=</ds:Y></ds:DSAKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></Security>
;   </Header>
;   <Body Id="abc">
;     <z:FooBar xmlns:z="https://www.example-code.com"/>
;   </Body>
; </Envelope>

; The above signed XML contains the DSA public key in the DSAKeyValue fragment (within the ds:KeyInfo).
; The signature can easily be verified like this:

$oVerifier = ObjCreate("Chilkat.XmlDSig")

; First load the XML containing the signature(s) to be verified.
$bSuccess = $oVerifier.LoadSignatureSb($oSbXml)
If ($bSuccess <> True) Then
    ConsoleWrite($oVerifier.LastErrorText & @CRLF)
    Exit
EndIf

Local $bVerified = $oVerifier.VerifySignature(True)
If ($bVerified <> True) Then
    ConsoleWrite($oVerifier.LastErrorText & @CRLF)
EndIf

ConsoleWrite("Signature verified = " & $bVerified & @CRLF)