Zig

Extract SignatureValue from Signed XML

See more XML Digital Signatures Examples

Demonstrates how to extract the signature value from signed 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 will work with the following signed XML, which as been reformatted for readability.

    // <?xml version="1.0" encoding="utf-8"?>
    // <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
    //     <SOAP-ENV:Header>
    //         <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" SOAP-ENV:mustUnderstand="1">
    //             <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#">
    //                         <InclusiveNamespaces xmlns="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="wsse SOAP-ENV"/>
    //                     </ds:CanonicalizationMethod>
    //                     <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
    //                     <ds:Reference URI="#Body">
    //                         <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>OwgHPZNfDkXnZsjpfzXqAcT3RV3HzmTsEy2bP44FJ0M=</ds:DigestValue>
    //                     </ds:Reference>
    //                 </ds:SignedInfo>
    //                 <ds:SignatureValue>C+7FWngU....DJFBcdg==</ds:SignatureValue>
    //                 <ds:KeyInfo>
    //                     <ds:KeyValue>
    //                         <ds:RSAKeyValue>
    //                             <ds:Modulus>sXeRhM55P13.....NAcibRw==</ds:Modulus>
    //                             <ds:Exponent>AQAB</ds:Exponent>
    //                         </ds:RSAKeyValue>
    //                     </ds:KeyValue>
    //                 </ds:KeyInfo>
    //             </ds:Signature>
    //         </wsse:Security>
    //     </SOAP-ENV:Header>
    //     <SOAP-ENV:Body xmlns:SOAP-SEC="http://schemas.xmlsoap.org/soap/security/2000-12" SOAP-SEC:id="Body">
    //         <z:FooBar xmlns:z="http://example.com"/>
    //     </SOAP-ENV:Body>
    // </SOAP-ENV:Envelope>

    // -----------------------------------------------------------------------------------------
    // There are a number of ways we can get the contents of the  <ds:SignatureValue>...</ds:SignatureValue>

    const file_path = "qa_data/xml_dsig_testing/sample_to_show_how_to_extract_sig.xml";

    // If you know there will only be a single SignatureValue in the XML, you don't need to parse XML.
    // Just do quick and simple string search..
    // For example:
    const sb = try chilkat.StringBuilder.init();
    defer sb.deinit();
    sb.loadFile(file_path, "utf-8") catch {
        std.debug.print("Failed to load file.\n", .{});
        return;
    };

    var base64_sig: [:0]const u8 = try sb.getBetween(alloc, "SignatureValue>", "</");
    std.debug.print("base64Sig = {s}\n", .{base64_sig});

    // -----------------------------------------------------------------------------------------
    // If the XML might contain multiple signatures, but the signatures will always be located in the
    // same place, then you can (beforehand) copy a sample signed XML into Chilkat's online tool
    // at Generate Parsing Code from XML
    // to get the path to the SignatureValue.  For example, the line of code generated for the SignatureValue
    // for the above XML is:
    // string ds_SignatureValue = xml.GetChildContent("SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue");

    // So you can simply use that path..
    const xml = try chilkat.Xml.init();
    defer xml.deinit();
    try xml.loadXmlFile(file_path);
    // Assume success..

    base64_sig = try xml.getChildContent(alloc, "SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue");
    std.debug.print("base64Sig = {s}\n", .{base64_sig});

    // -----------------------------------------------------------------------------------------
    // Or perhaps you don't know where the signature is located in the XML.
    // You can search for the tag..
    if (xml.searchForTag(xml, "*:SignatureValue")) |x_sig_val| {
        defer x_sig_val.deinit();
        std.debug.print("base64Sig = {s}\n", .{try x_sig_val.getContent(alloc)});
    } else |_| {
        std.debug.print("No SignatureValue found.\n", .{});
    }
}