Lua

Decrypt a govtalk.gov.uk SOAP GovTalkMessage

See more Encryption Examples

Demonstrates how to decrypt the content contained in the XML of a GovTalkMessage SOAP response. Lua

local chilkat = require("chilkat")

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

-- The GovTalkMessage response looks something like this:

-- <?xml version="1.0" encoding="utf-8"?>
-- <GovTalkMessage xmlns="http://www.govtalk.gov.uk/CM/envelope">
--   <EnvelopeVersion>3.1</EnvelopeVersion>
--   <Header>
--     <MessageDetails>
--       <Class>CSSZ_DZDPN</Class>
--       <Qualifier>request</Qualifier>
--       <Function>submit</Function>
--       <TransactionID />
--       <AuditID />
--       <CorrelationID>aaaaa</CorrelationID>
--       <ResponseEndPoint PollInterval="0" />
--       <Transformation>XML</Transformation>
--       <GatewayTest />
--       <GatewayTimestamp />
--     </MessageDetails>
--     <SenderDetails>
--       <IDAuthentication>
--         <SenderID />
--         <Authentication>
--           <Method>clear</Method>
--           <Role />
--           <Value />
--         </Authentication>
--       </IDAuthentication>
--       <X509Certificate />
--       <EmailAddress>somebody@example.com</EmailAddress>
--     </SenderDetails>
--   </Header>
--   <GovTalkDetails>
--     <Keys>
--       <Key Type="vars">9999999999</Key>
--     </Keys>
--     <GatewayAdditions>
--       <Source>VREP</Source>
--     </GatewayAdditions>
--   </GovTalkDetails>
--   <Body>
--     <Message xmlns="http://www.cssz.cz/XMLSchema/envelope" version="1.2" eType="DZDPN20">
--       <Header>
--         <Signature xmlns:dt="urn:schemas-microsoft-com:datatypes" dt:dt="bin.base64">MIIJ0A ... UMw=
-- </Signature>
--         <Vendor productName="some product name" version="2019" />
--       </Header>
--       <Body xmlns:dt="urn:schemas-microsoft-com:datatypes" encrypted="yes" contentEncoding="gzip" dt:dt="bin.base64">MIIF2w ... N2vW</Body>
--     </Message>
--   </Body>
-- </GovTalkMessage>

-- We want to get the content of the Body and decrypt it.

-- First, let's get the content of the Body XML element, which is a base64 string starting with MIIF2w...

local xml = chilkat.Xml.new()
local success = xml:load_xml_file("qa_data/xml/govTalkMessageResponse.xml")
if not success then
    print(xml.last_error_text)
    return
end

local Body = xml:get_child_content("Body|Message|Body")
print(Body)

local cert = chilkat.Cert.new()
success = cert:load_pfx_file("qa_data/pfx/govTalkMessage_aaa.pfx", "aaa")
if not success then
    print(cert.last_error_text)
    return
end

local crypt = chilkat.Crypt2.new()
crypt.crypt_algorithm = "pki"
success = crypt:set_decrypt_cert(cert)
if not success then
    print(crypt.last_error_text)
    return
end

local bd = chilkat.BinData.new()
-- Append the bytes to bd.
success = bd:append_encoded(Body, "base64")

-- Decrypt in-place.
success = crypt:decrypt_bd(bd)
if not success then
    print(crypt.last_error_text)
    return
end

-- Save the decrypted data to a file.
success = bd:write_file("qa_output/out.dat")

-- If the decrypted data is non-text (binary) then we can examine it in an encoding, such as hex:
print("Decrypted bytes as hex: " .. bd:get_encoded("hex"))