Lua Requires Chilkat v11.0.0+

Verify Opaque Signature and Retrieve Signing Certificates

See more Digital Signatures Examples

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign. 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()

-- Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
local success = crypt:verify_p7_m("qa_data/p7m/opaqueSig.p7", "qa_output/originalData.dat")
if not success then
    print(crypt.last_error_text)
    return
end

-- Alternatively, we can do it in memory...
local binData = chilkat.BinData.new()
success = binData:load_file("qa_data/p7m/opaqueSig.p7")
-- Your app should check for success, but we'll skip the check for brevity..

-- If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
success = crypt:opaque_verify_bd(binData)
if not success then
    print(crypt.last_error_text)
    return
end

-- For our testing, we signed some text, so we can get it from the binData..
print("Original Data:")
print(binData:get_string("utf-8"))

-- After any method call that verifies a signature, the crypt object will contain the certificate(s)
-- that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

-- Get each signing certificate, and build the certificate chain for each.
local cert = chilkat.Cert.new()
local certChain = chilkat.CertChain.new()
local numCerts = crypt.num_signer_certs
local i = 0
while i < numCerts do
    crypt:last_signer_cert(i, cert)
    print(cert.subject_dn)

    success = cert:build_cert_chain(certChain)
    if not success then
        print(cert.last_error_text)
        return
    end

    i = i + 1
end