Sample code for 30+ languages & platforms
Visual FoxPro

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.

Chilkat Visual FoxPro Downloads

Download Chilkat for Visual FoxPro
Visual FoxPro 
LOCAL lnSuccess
LOCAL lcUrl
LOCAL loHttp
LOCAL loSbXml
LOCAL loDsaKey
LOCAL loXmlSigGen
LOCAL loVerifier
LOCAL lnBVerified

lnSuccess = 0

* 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..

lcUrl = "https://www.chilkatsoft.com/exampleData/xmlToSign.xml"
loHttp = CreateObject('Chilkat.Http')
loSbXml = CreateObject('Chilkat.StringBuilder')
lnSuccess = loHttp.QuickGetSb(lcUrl,loSbXml)
IF (lnSuccess <> 1) THEN
    ? loHttp.LastErrorText
    RELEASE loHttp
    RELEASE loSbXml
    CANCEL
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".
loDsaKey = CreateObject('Chilkat.PrivateKey')
lnSuccess = loDsaKey.LoadEncryptedPemFile("qa_data/dsa/dsa1024_secret.pem","secret")
IF (lnSuccess <> 1) THEN
    ? loDsaKey.LastErrorText
    RELEASE loHttp
    RELEASE loSbXml
    RELEASE loDsaKey
    CANCEL
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.
* 

loXmlSigGen = CreateObject('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.
loXmlSigGen.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.
loXmlSigGen.AddSameDocRef("abc","sha1","EXCL_C14N","","")

* Provide the DSA key to be used for signing:
loXmlSigGen.SetPrivateKey(loDsaKey)

* 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.
loXmlSigGen.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.
lnSuccess = loXmlSigGen.CreateXmlDSigSb(loSbXml)
IF (lnSuccess <> 1) THEN
    ? loXmlSigGen.LastErrorText
    RELEASE loHttp
    RELEASE loSbXml
    RELEASE loDsaKey
    RELEASE loXmlSigGen
    CANCEL
ENDIF

* Examine the signed XML:
? loSbXml.GetAsString()

* 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:

loVerifier = CreateObject('Chilkat.XmlDSig')

* First load the XML containing the signature(s) to be verified.
lnSuccess = loVerifier.LoadSignatureSb(loSbXml)
IF (lnSuccess <> 1) THEN
    ? loVerifier.LastErrorText
    RELEASE loHttp
    RELEASE loSbXml
    RELEASE loDsaKey
    RELEASE loXmlSigGen
    RELEASE loVerifier
    CANCEL
ENDIF

lnBVerified = loVerifier.VerifySignature(1)
IF (lnBVerified <> 1) THEN
    ? loVerifier.LastErrorText
ENDIF

? "Signature verified = " + STR(lnBVerified)

RELEASE loHttp
RELEASE loSbXml
RELEASE loDsaKey
RELEASE loXmlSigGen
RELEASE loVerifier