Java

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.

Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Http;
import com.chilkatsoft.chilkat2.PrivateKey;
import com.chilkatsoft.chilkat2.StringBuilder;
import com.chilkatsoft.chilkat2.XmlDSig;
import com.chilkatsoft.chilkat2.XmlDSigGen;

public class ChilkatExample {

    public static void main(String[] args) {
        // 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..

        String url = "https://www.chilkatsoft.com/exampleData/xmlToSign.xml";
        Http http = new Http();
        StringBuilder sbXml = new StringBuilder();
        try {
            http.quickGetSb(url, sbXml);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // 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".
        PrivateKey dsaKey = new PrivateKey();
        try {
            dsaKey.loadEncryptedPemFile("qa_data/dsa/dsa1024_secret.pem", "secret");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // 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.
        //

        XmlDSigGen xmlSigGen = new 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.
        xmlSigGen.setSigLocation("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.
        xmlSigGen.addSameDocRef("abc", "sha1", "EXCL_C14N", "", "");

        // Provide the DSA key to be used for signing:
        xmlSigGen.setPrivateKey(dsaKey);

        // 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.
        xmlSigGen.setSignedInfoDigestMethod("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.
        try {
            xmlSigGen.createXmlDSigSb(sbXml);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Examine the signed XML:
        System.out.println(sbXml.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:

        XmlDSig verifier = new XmlDSig();

        // First load the XML containing the signature(s) to be verified.
        try {
            verifier.loadSignatureSb(sbXml);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        boolean bVerified;
        try {
            verifier.verifySignature(true);
            bVerified = true;
        } catch (ChilkatException e) {
            bVerified = false;
        }
        if (!bVerified) {
            System.out.println(verifier.getLastErrorText());
        }

        System.out.println("Signature verified = " + bVerified);
    }
}