Dart
Dart
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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import 'package:chilkat/chilkat.dart';
void main() {
// 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..
final url = 'https://www.chilkatsoft.com/exampleData/xmlToSign.xml';
final http = CkHttp();
final sbXml = CkStringBuilder();
try {
http.quickGetSb(url, sbXml);
} on ChilkatException catch (e) {
print(e.lastErrorText);
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".
final dsaKey = CkPrivateKey();
try {
dsaKey.loadEncryptedPemFile('qa_data/dsa/dsa1024_secret.pem', 'secret');
} on ChilkatException catch (e) {
print(e.lastErrorText);
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.
//
final xmlSigGen = CkXmlDSigGen();
// 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.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.
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.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.
try {
xmlSigGen.createXmlDSigSb(sbXml);
} on ChilkatException catch (e) {
print(e.lastErrorText);
return;
}
// Examine the signed XML:
print(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:
final verifier = CkXmlDSig();
// First load the XML containing the signature(s) to be verified.
try {
verifier.loadSignatureSb(sbXml);
} on ChilkatException catch (e) {
print(e.lastErrorText);
return;
}
var bVerified = true;
try {
verifier.verifySignature(true);
} on ChilkatException {
bVerified = false;
}
if (!bVerified) {
print(verifier.lastErrorText);
}
print('Signature verified = $bVerified');
}