Lua Requires Chilkat v11.0.0+
Send a Signed Email using RSASSA-PSS with SHA256

Demonstrates how to sign and send an email using the RSASSA-PSS signing algorithm with the SHA256 hash algorithm. .
Chilkat Lua Downloads

Lua
local chilkat = require("chilkat")

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

-- Get a digital certificate with private key from a .pfx
-- (Chilkat has many different ways to provide a cert + private key for siging.
-- Using a PFX is just one possible option.)
local pfx = chilkat.Pfx.new()
local success = pfx:load_pfx_file("qa_data/rsassa-pss/privatekey.pfx", "PFX_PASSWORD")
if not success then
    print(pfx.last_error_text)
    return
end

local email = chilkat.Email.new()

-- Create a simple email.
email.subject = "Sample RSASSA-PSS Signed Email"
email.body = "Sample RSASSA-PSS Signed Email"
email.from = "from_name@mydomain.com"
-- Add one ore more recipients..
email:add_to("Chilkat Support", "support@chilkatsoft.com")
email:add_to("Chilkat GMail", "chilkat.support@gmail.com")

-- Indicate that the email is to be signed, and that we want to use RSASSA-PSS.
email.send_signed = true
email.signing_alg = "pss"
email.signing_hash_alg = "sha256"

-- Get the certificate to be used for signing.
-- (The typical case for a PFX is that it contains a cert with an associated private key,
-- as well as other certificates in the chain of authentication.  The cert with the private
-- key should be in the first position at index 0.)

local cert = chilkat.Cert.new()
success = pfx:cert_at(0, cert)
if not success then
    print(pfx.last_error_text)
    return
end

-- Tell the email object to use this cert (and private key) for signing.
email:set_signing_cert(cert)

local mailman = chilkat.MailMan.new()

-- Set the SMTP settings for your email account on your mail server.
mailman.smtp_username = "SMTP_LOGIN"
mailman.smtp_password = "SMTP_PASSWORD"
mailman.smtp_host = "MY_SMTP_DOMAIN_OR_IP"
mailman.smtp_port = 587
mailman.start_tls = true

-- Signed email can be sent in two different ways.
-- In a multipart/signed email, the signature is attached as a separate MIME part.
-- In an opaque email (signedData) the content of the email is encapsulated within the signature
-- and the email is sent as "application/pkcs7-mime".
-- Either should be fine, but some receiving systems might require one or the other..
mailman.opaque_signing = false

-- Send the email.  The mailman will sign the email as directed by the
-- property settings of the email object.
success = mailman:send_email(email)
if not success then
    print(mailman.last_error_text)
    return
end

success = mailman:close_smtp_connection()
if not success then
    print("Connection to SMTP server not closed cleanly.")
end

print("Mail Sent!")

-- -----------------------------------------------------------
-- This is the MIME of the RSASSA-PSS signed email that was sent

--     MIME-Version: 1.0
--     Date: Thu, 20 Apr 2017 10:14:58 -0500
--     Message-ID: <3682A87344CB3A4FB5EB5BC9908C0C4DA01DA461@CHILKAT13>
--     Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha256;
--      boundary="------------050103020705000601010800"
--     X-Priority: 3 (Normal)
--     Subject: Sample RSASSA-PSS Signed Email
--     From: support@chilkatsoft.com
--     To: "Chilkat Support" <support@chilkatsoft.com>,
--      "Chilkat GMail" <chilkat.support@gmail.com>
--
--     --------------050103020705000601010800
--     Content-Type: text/plain; format=flowed
--     Content-Transfer-Encoding: 7bit
--
--     Sample RSASSA-PSS Signed Email
--     --------------050103020705000601010800
--     Content-Transfer-Encoding: base64
--     Content-Type: application/pkcs7-signature; name="smime.p7s"
--     Content-Disposition: attachment; filename="smime.p7s"
--
--     MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
--     ggL4MIIC9DCCAl2gAwIBAgIJAMPsJCT11cniMA0GCSqGSIb3DQEBCwUAMIGSMQswCQYDVQQGEwJB
--     VTERMA8GA1UECAwIVmljdG9yaWExEjAQBgNVBAcMCU1lbGJvdXJuZTEhMB8GA1UECgwYSW50ZXJu
--     ZXQgV2lkZ2l0cyBQdHkgTHRkMQ8wDQYDVQQDDAZXaWRnZXQxKDAmBgkqhkiG9w0BCQEWGWFkbWlu
--     QGludGVybmV0d2lkZ2V0cy5jb20wHhcNMTYxMTAxMTY1MjMyWhcNMjExMDMxMTY1MjMyWjCBkjEL
--     MAkGA1UEBhMCQVUxETAPBgNVBAgMCFZpY3RvcmlhMRIwEAYDVQQHDAlNZWxib3VybmUxITAfBgNV
--     BAoMGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDEPMA0GA1UEAwwGV2lkZ2V0MSgwJgYJKoZIhvcN
--     AQkBFhlhZG1pbkBpbnRlcm5ldHdpZGdldHMuY29tMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKB
--     gQDGIdoCjyavs+F/Rm0VIB4m6O7VL1j+1IqieoR9NEX2GQvu2VCdceyxf9qaw1bxipEvjLwUkw7M
--     e+BTlLpWQbBMH87s6KpsC8MVyXhMLpP0oM8NFix/vLz2wdLhUh7CZvJA0plqkJk9bj57QIu+EO1k
--     tUHM2DFb6sckvCL2yybD1wIDAQABo1AwTjAdBgNVHQ4EFgQUONKKu2zsXIrinWxIGT654vrcQwsw
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--     41wQ5A==
--
--     --------------050103020705000601010800--