Lua

Add a Detached Signature (Header Placement Control)

Demonstrates the Chilkat Mime.AddDetachedSignature2 method, which creates the same multipart/signed structure as AddDetachedSignature, with a second argument controlling whether the existing message header fields are transferred to the new outer entity.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Signing wraps the content in a new outer multipart/signed, which raises the question of where the message-level headers (Subject, From, To) should live. This variant lets you choose: transfer them up to the outer entity so the signed message looks like a normal email, or leave them on the inner part. Transferring is typical for email; the finer control matters when the signed entity is embedded in a larger structure.

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Lua

local chilkat = require("chilkat")

local mime = chilkat.Mime.new()
local success = mime:set_body_from_plain_text("This message will be signed.")
if not success then
    print(mime.last_error_text)
    return
end

-- Load the signing certificate (which must have access to its private key) from a PFX file.
-- The PFX password should come from a secure source rather than being hard-coded.
local pfxPassword = "myPfxPassword"
local cert = chilkat.Cert.new()
success = cert:load_pfx_file("qa_data/signer.pfx", pfxPassword)
if not success then
    print(cert.last_error_text)
    return
end

-- AddDetachedSignature2 is the same as AddDetachedSignature, but the 2nd argument controls whether
-- the existing message header fields are transferred to the new outer multipart/signed entity.
local transferHeaderFields = true
success = mime:add_detached_signature2(cert, transferHeaderFields)
if not success then
    print(mime.last_error_text)
    return
end

success = mime:save_mime("qa_output/signed.eml")
if not success then
    print(mime.last_error_text)
    return
end

print("Detached signature added (headers transferred).")