Lua

Get an S/MIME Signing Time

Demonstrates the Chilkat Mime.GetSignatureSigningTimeStr method, which returns the CMS signingTime attribute for the signer at a zero-based index, as an RFC 822-style date string in GMT. The only argument is the signer index.

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: This is the timestamp the signer asserted at signing — useful for "when was this signed" audit trails and for evaluating whether the signing certificate was valid at that moment. Because it is a signed attribute, it is tamper-evident. Guard the call with HasSignatureSigningTime, since the attribute is optional. Note it is the signer's claim, not a trusted third-party timestamp.

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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, get the CMS signingTime for each signer that has one, as an RFC 822 date string
-- in GMT.  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
    -- Only signers that included a signing time have one to retrieve.
    if mime:has_signature_signing_time(i) then
        local signingTime = mime:get_signature_signing_time_str(i)
        if not mime.last_method_success then
            print(mime.last_error_text)
            return
        end

        print("Signer " .. i .. " signing time: " .. signingTime)
    end
end