Zig

Create XML Signature with External XML Reference

See more XML Digital Signatures Examples

Demonstrates how to create an XML digital signature where the referenced data is external. In this case, the data is an XML file located at the following URL: https://www.chilkatsoft.com/data/helloWorld.xml Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

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

    // This example inserts an XML signature in the following XML:

    // <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    // <abc>
    //   <xyz>
    //     <name>helloWorld.xml</name>
    //     <url>https://www.chilkatsoft.com/data/helloWorld.xml</url>
    //   </xyz>
    // </abc>

    // Build the above XML to be signed.
    const xml = try chilkat.Xml.init();
    defer xml.deinit();
    xml.setTag("abc");
    xml.updateChildContent("xyz|name", "helloWorld.xml");
    xml.updateChildContent("xyz|url", "https://www.chilkatsoft.com/data/helloWorld.xml");

    const cert = try chilkat.Cert.init();
    defer cert.deinit();

    cert.loadPfxFile("qa_data/pfx/test_secret.pfx", "secret") catch {
        std.debug.print("{s}\n", .{try cert.getLastErrorText(alloc)});
        return;
    };

    const gen = try chilkat.XmlDSigGen.init();
    defer gen.deinit();

    // Indicate the location within the XML the Signature will be inserted.
    gen.setSigLocation("abc|xyz");

    // Get the content of the XML data to be referenced.
    const http = try chilkat.Http.init();
    defer http.deinit();
    const sb_external_xml = try chilkat.StringBuilder.init();
    defer sb_external_xml.deinit();
    http.quickGetSb("https://www.chilkatsoft.com/data/helloWorld.xml", sb_external_xml) catch {
        std.debug.print("{s}\n", .{try http.getLastErrorText(alloc)});
        return;
    };

    gen.addExternalXmlRef("https://www.chilkatsoft.com/data/helloWorld.xml", sb_external_xml, "sha256", "EXCL_C14N", "") catch {
        std.debug.print("{s}\n", .{try gen.getLastErrorText(alloc)});
        return;
    };

    // Provide the private key for signing via the certificate, and indicate that
    // we want the base64 of the certificate embedded in the KeyInfo.
    gen.setKeyInfoType("X509Data");
    gen.setX509Type("Certificate");

    const b_use_private_key = true;
    gen.setX509Cert(cert, b_use_private_key) catch {
        std.debug.print("{s}\n", .{try gen.getLastErrorText(alloc)});
        return;
    };

    // Indicate we want an indented signature for readability.
    // This can be removed after debugging is finished..
    gen.setBehaviors("IndentedSignature");

    // Now create and insert the Signature
    const sb_xml = try chilkat.StringBuilder.init();
    defer sb_xml.deinit();
    xml.getXmlSb(sb_xml) catch {};
    gen.createXmlDSigSb(sb_xml) catch {
        std.debug.print("{s}\n", .{try gen.getLastErrorText(alloc)});
        return;
    };

    // Examine the XML with the digital signature inserted
    std.debug.print("{s}\n", .{try sb_xml.getAsString(alloc)});

    // Here is the output:

    // <?xml version="1.0" encoding="utf-8"?>
    // <abc>
    //     <xyz>
    //         <name>helloWorld.xml</name>
    //         <url>https://www.chilkatsoft.com/data/helloWorld.xml</url>
    //     <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/2001/04/xmldsig-more#rsa-sha256"/>
    //     <ds:Reference URI="https://www.chilkatsoft.com/data/helloWorld.xml">
    //       <ds:Transforms>
    //         <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
    //       </ds:Transforms>
    //       <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
    //       <ds:DigestValue>H/s775OZhel6wdBhe02l4LK6m0lkplOisKxAbVwWxp0=</ds:DigestValue>
    //     </ds:Reference>
    //   </ds:SignedInfo>
    //   <ds:SignatureValue>UruwnBqh..Ll4IzUA==</ds:SignatureValue>
    //   <ds:KeyInfo>
    //     <ds:X509Data>
    //       <ds:X509Certificate>MIIHAz...nUZWCaDE=</ds:X509Certificate>
    //     </ds:X509Data>
    //   </ds:KeyInfo>
    // </ds:Signature></xyz>
    // </abc>

    // Let's verify the signature...
    const verifier = try chilkat.XmlDSig.init();
    defer verifier.deinit();
    verifier.loadSignatureSb(sb_xml) catch {
        std.debug.print("{s}\n", .{try verifier.getLastErrorText(alloc)});
        return;
    };

    // Let's examine the external references, and fetch the data for each..
    const sb_external_data = try chilkat.StringBuilder.init();
    defer sb_external_data.deinit();
    const num_refs = verifier.getNumReferences();
    var i: i32 = 0;
    while (i < num_refs) {
        const b_external = verifier.isReferenceExternal(i);
        if (b_external) {
            const uri = try verifier.referenceUri(alloc, i);

            // We're assuming the URI is an https:// or http:// URL...
            // Let's also assume we know that the referenced data is text and we want the utf-8 byte representation.
            sb_external_data.clear();
            http.quickGetSb(uri, sb_external_data) catch {
                std.debug.print("{s}\n", .{try http.getLastErrorText(alloc)});
                return;
            };

            // Because the referenced external data was explicitly XML, it was the canonicalized XML that was digested.
            // We need to canonicalize the XML in the same way as when signed.
            const canon_xml = try verifier.canonicalizeXml(alloc, try sb_external_data.getAsString(alloc), "EXCL_C14N", false);
            sb_external_data.setString(canon_xml) catch {};

            verifier.setRefDataSb(i, sb_external_data, "utf-8") catch {
                std.debug.print("{s}\n", .{try verifier.getLastErrorText(alloc)});
                return;
            };
        }

        i = i + 1;
    }

    // Now that we have the external data available, we can verify the reference digest(s) and the signature.
    verifier.verifySignature(true) catch {
        std.debug.print("{s}\n", .{try verifier.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Signature verified!\n", .{});
}