Lua Requires Chilkat v11.0.0+

Decrypt S/MIME and Verify S/MIME Signatures

See more MIME Examples

_LANGUAGE_ example to decrypt S/MIME and verify S/MIME signatures. The S/MIME is unwrapped to get the original MIME prior to signing/encrypting. Lua

local chilkat = require("chilkat")

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

local mime = chilkat.Mime.new()

-- Load an S/MIME message from a file:
local success = mime:load_mime_file("signedMime.txt")
if not success then
    print(mime.last_error_text)
    return
end

-- The ContainsEncryptedParts/ContainsSignedParts methods
-- can be called to determine if the MIME is encrypted and/or signed:
local isEncrypted = mime:contains_encrypted_parts()
local isSigned = mime:contains_signed_parts()

-- We don't want the "unwrap extras".  You'll see what those
-- are in a few moments...
mime.unwrap_extras = false

-- To verify the signature, call UnwrapSecurity.  This will
-- verify the signature(s) and decrypt the S/MIME and restore
-- the MIME to the unsigned/unencrypted state.
-- The results of what was found are present in the MIME object's
-- properties, as well as extra header fields that are added
-- to the unwrapped MIME.
success = mime:unwrap_security()
if not success then
    -- UnwrapSecurity returns true if all signatures were
    -- verified and all parts decrypted.
    print(mime.last_error_text)
    return
end

-- The mime.UnwrapExtras property controls whether or not
-- these additional fields are added to the unwrapped MIME:
--
-- X-NumPartsSigned: 1
-- X-SignaturesValid: yes
-- X-NumPartsEncrypted: 1
-- X-Decrypted: no
--
-- The X-NumPartsSigned/X-SignaturesValid headers are added
-- if the MIME was signed.
--
-- The X-NumPartsEncrypted/X-Decrypted headers are added
-- if the MIME was encrypted.
--

-- If the MIME was signed, get the certificate used for signing.
if isSigned then
    local signerCert = chilkat.Cert.new()

    -- The NumSignerCerts property indicates how many certificates
    -- were used for signing.  This example will assume the value is 1.
    -- To get the 1st signer cert, call LastSignerCert with an index of 0:
    success = mime:last_signer_cert(0, signerCert)
    if success then
        print("**** Signer Cert: " .. signerCert.subject_cn)
    end
end

-- If the MIME was encrypted, get the certificate used for decryption
if isEncrypted then
    -- The NumDecryptCerts property indicates how many certificates
    -- were used for decrypting.  This example will assume the value is 1.
    -- To get the 1st decrypt cert, call LastDecryptCert with an index of 0:
    local decryptCert = chilkat.Cert.new()
    success = mime:last_decrypt_cert(0, decryptCert)
    if success then
        print("**** Decrypt Cert: " .. decryptCert.subject_cn)
    end
end

-- Display the unwrapped MIME:
print(mime:get_mime())

-- Save the unwrapped MIME to a file:
success = mime:save_mime("unwrappedMime.txt")