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Lua

Create an Opaque Signature with a Separate Private Key

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Demonstrates the Chilkat Mime.ConvertToSignedPk method, which creates an opaque signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

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: The separate-key form of ConvertToSigned, for when the certificate and private key are not bundled together. It produces the same opaque CMS signed-data result; only the source of the key material differs.

Chilkat Lua Downloads

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 certificate and its private key separately.
local cert = chilkat.Cert.new()
success = cert:load_from_file("qa_data/signer.cer")
if not success then
    print(cert.last_error_text)
    return
end

local privKey = chilkat.PrivateKey.new()
success = privKey:load_pem_file("qa_data/signer_privkey.pem")
if not success then
    print(privKey.last_error_text)
    return
end

-- Create an opaque signature when the certificate and private key are supplied separately.  The
-- 1st argument is the signer certificate and the 2nd is its private key.
success = mime:convert_to_signed_pk(cert, privKey)
if not success then
    print(mime.last_error_text)
    return
end

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

print("Message converted to an opaque signed message.")