Lua

Encrypt a file to a PKCS7 encrypted message using multiple certificates from different users

See more Encryption Examples

Demonstrates how to encrypt a file to a PKCS7 encrypted message using multiple certificates from different users. Any one of the users can decrypt using his/her own certificate + private key.

Note: When doing public key encryption, it is the public key that is used to encrypt. The private key is required 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()

-- Tell the crypt object to use 3 certificates.
-- Do this by calling AddEncryptCert for each certificate.

-- Load a 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:add_encrypt_cert(cert1)

local cert2 = chilkat.Cert.new()
success = cert2:load_from_file("qa_data/user2/cert_user2.pem")
crypt:add_encrypt_cert(cert2)

local cert3 = chilkat.Cert.new()
success = cert3:load_from_file("qa_data/user3/cert_user3.pem")
crypt:add_encrypt_cert(cert3)

-- 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-128 for the
-- bulk encryption.
crypt.crypt_algorithm = "pki"
crypt.pkcs7_crypt_alg = "aes"
crypt.key_length = 128
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")

-- Now indicate that the PKCS7 output is to be returned in the base64 encoding.
crypt.encoding_mode = "base64"

print("OK.")