Lua

Encrypt a File to a PKCS7 (CMS) Message

Shows how to encrypt a file into a PKCS7 encrypted message using the recipient's certificate. Public-key encryption requires no private key. However, the recipient's private key is necessary for decryption. Lua

local chilkat = require("chilkat")

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

local crypt = chilkat.Crypt2.new()

-- Load the recipient's digital certificate.
-- We don't need the private key for encryption.
-- Only the public key is needed (which is included in a certificate).
local cert1 = chilkat.Cert.new()
local success = cert1:load_from_file("qa_data/user1/cert_user1.pem")
-- Assume success for the example, but make sure your application checks for success/failure...
crypt:set_encrypt_cert(cert1)

-- Indicate that we want PKI encryption (i.e. public-key infrastructure)
-- to produce a CMS message (Cryptographic Message Syntax/PKCS7),
-- that is be created with RSAES-OAEP padding, SHA256, and AES-256 for the
-- bulk encryption.
crypt.crypt_algorithm = "pki"
crypt.pkcs7_crypt_alg = "aes"
crypt.key_length = 256
crypt.oaep_hash = "sha256"
crypt.oaep_padding = true

-- Load the file to be encrypted...
local fileData = chilkat.BinData.new()
success = fileData:load_file("qa_data/jpg/penguins.jpg")
-- Your app should check for success/failure..

-- Encrypt the data.  The contents of the fileData object are replaced with the PKCS7 encrypted message.
success = crypt:encrypt_bd(fileData)
if not success then
    print(crypt.last_error_text)
    return
end

-- Save the PKCS7 encrypted message to a file..
success = fileData:write_file("qa_output/pkcs7_encrypted.p7")

print("OK.")