Lua

Specify a Certificate for Encrypted Email

Demonstrates the Chilkat Email.AddEncryptCert method, which explicitly specifies a certificate to use when sending encrypted email. Call it once per recipient certificate; ClearEncryptCerts clears the list. This example loads a recipient certificate, registers it, and enables encrypted sending.

Background: When encrypting to multiple people, each recipient needs to be able to decrypt with their own private key. S/MIME handles this by encrypting the message's one-time content key separately under each recipient's public certificate and including all of those wrapped keys in the message. AddEncryptCert is how you build that recipient list — one call per certificate — giving explicit control over exactly whose certificates are used rather than relying on automatic lookup.

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Lua

local chilkat = require("chilkat")

-- Demonstrates the AddEncryptCert method, which explicitly specifies a certificate for
-- sending encrypted email.  Call it once per recipient certificate.  Use ClearEncryptCerts
-- to clear the list.

local email = chilkat.Email.new()
email.subject = "Encrypted email"
email.body = "Encrypted to the specified recipient certificate(s)."
email.from = "alice@example.com"
email:add_to("Bob", "bob@example.com")

-- Load a recipient certificate (public key) and add it to the encryption cert list.
local cert = chilkat.Cert.new()
local success = cert:load_from_file("qa_data/certs/recipient.cer")
if not success then
    print(cert.last_error_text)
    return
end

success = email:add_encrypt_cert(cert)
if not success then
    print(email.last_error_text)
    return
end

-- Request encrypted sending.
email.send_encrypted = true

print("Added the recipient's encryption certificate.")

-- Note: The path "qa_data/certs/recipient.cer" is a relative local filesystem path,
-- relative to the current working directory of the running application.