Lua

Extract SignatureValue from Signed XML

See more XML Digital Signatures Examples

Demonstrates how to extract the signature value from signed XML. Lua

local chilkat = require("chilkat")

-- 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>

local filePath = "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:
local sb = chilkat.StringBuilder.new()
local success = sb:load_file(filePath, "utf-8")
if not success then
    print("Failed to load file.")
    return
end

local base64Sig = sb:get_between("SignatureValue>", "</")
print("base64Sig = " .. base64Sig)

-- -----------------------------------------------------------------------------------------
-- 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..
local xml = chilkat.Xml.new()
success = xml:load_xml_file(filePath)
-- Assume success..

base64Sig = xml:get_child_content("SOAP-ENV:Header|wsse:Security|ds:Signature|ds:SignatureValue")
print("base64Sig = " .. base64Sig)

-- -----------------------------------------------------------------------------------------
-- Or perhaps you don't know where the signature is located in the XML.
-- You can search for the tag..
local xSigVal = xml:search_for_tag(xml, "*:SignatureValue")
if xml.last_method_success then
    print("base64Sig = " .. xSigVal.content)
else
    print("No SignatureValue found.")
end