Lua Requires Chilkat v9.5.0.83+

Create CMS Signed File (PDF) with Multiple Signing Certificates

See more Digital Signatures Examples

Demonstrates how to sign a file by adding multiple signatures (multiple certificates). This example signs a PDF file to produce an output file that is a CMS signature wrapping the original PDF. (Note: This is different than modifying a PDF by injecting a signature into the PDF file format.) Lua

local chilkat = require("chilkat")

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

local crypt = chilkat.Crypt2.new()

local cert1 = chilkat.Cert.new()
local success = cert1:load_pfx_file("qa_data/pfx/cert_test123.pfx", "test123")
if not success then
    print(cert1.last_error_text)
    return
end

local cert2 = chilkat.Cert.new()
success = cert2:load_pfx_file("qa_data/pfx/test_secret.pfx", "secret")
if not success then
    print(cert2.last_error_text)
    return
end

-- Tell the crypt component to use both certificates for signing.
-- When we create the signature, it will be signed by both certificates.
success = crypt:add_signing_cert(cert1)
if not success then
    print(crypt.last_error_text)
    return
end

success = crypt:add_signing_cert(cert2)
if not success then
    print(crypt.last_error_text)
    return
end

-- The CadesEnabled property applies to all methods that create PKCS7 signatures.
-- To create a CAdES-BES signature, set this property equal to true.
crypt.cades_enabled = true

crypt.hash_algorithm = "sha256"

-- We can sign any type of file, creating a .p7s as output.
-- The .p7s contains the signature and also embeds the data of the file that is signed.
local inFile = "qa_data/pdf/sample.pdf"
local p7sFile = "qa_output/sample.pdf.p7s"

-- Create the CAdES-BES attached signature, which contains the original data.
-- Note: Chilkat's function naming is not accurate.  CreateP7M creates a PKCS7 signature where the signed file
-- is contained within the signature.  CreateP7S creates a detached PKCS7 signature where the signed file
-- is NOT contained within the signature.  We want the data to be contained in the signature, therefore
-- we call CreateP7M even though we are naming our output file .p7s.
success = crypt:create_p7_m(inFile, p7sFile)
if not success then
    print(crypt.last_error_text)
    return
end

-- Verify the .p7s file and extract the original file from the .p7s.
local extractedToFilePath = "qa_output/sample.pdf"
success = crypt:verify_p7_m(p7sFile, extractedToFilePath)
if not success then
    print(crypt.last_error_text)
    return
end

print("Success!")