Lua

Check for an S/MIME Signing Time

Demonstrates the Chilkat Mime.HasSignatureSigningTime method, which returns whether the signer at a zero-based index included a CMS signingTime signed attribute. The only argument is the signer index; use NumSignerCerts for the count.

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: A signing time records when the signer claims to have signed, which matters for auditing and for validating a certificate that has since expired. It is an optional signed attribute, so not every signature has one — this predicate lets you check before calling GetSignatureSigningTimeStr, avoiding an error for signers that omitted it. Being a signed attribute, it is covered by the signature and cannot be altered undetected.

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Lua

local chilkat = require("chilkat")

local mime = chilkat.Mime.new()
local success = mime:load_mime_file("qa_data/signed.eml")
if not success then
    print(mime.last_error_text)
    return
end

-- After verifying, check whether each signer included a CMS signingTime signed attribute.  The
-- only argument is the zero-based signer index.
success = mime:verify()
if not success then
    print(mime.last_error_text)
    return
end

local n = mime.num_signer_certs
for i = 0, n - 1 do
    if mime:has_signature_signing_time(i) then
        print("Signer " .. i .. " included a signing time.")
    else
        print("Signer " .. i .. " did not include a signing time.")
    end
end