Lua

Encrypt File to PKCS7 .p7m

See more Encryption Examples

_LANGUAGE_ example to public-key encrypt a file creating a PKCS#7 .p7m file as output. Also demonstrates how to decrypt the .p7m to recover the original file. 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()

-- Indicate the public-key encryption is to be used.
-- Do this by setting the encryption algorithm equal
-- to "PKI" (an acroynm for public-key infrastructure).
crypt.crypt_algorithm = "PKI"

-- Indicate the inner symmetric encryption algorithm to be used.
-- possible values are "aes", "des", "3des", and "rc2".
-- For this example, we'll use 256-bit AES encryption.
crypt.pkcs7_crypt_alg = "aes"
crypt.key_length = 256

-- To encrypt, only a certificate w/ public key is needed.
-- (The certificate w/ private key is required for decryption.)

-- The LoadFromFile method can load virtually any certificate format:
-- 1. DER encoded binary X.509 (.CER)
-- 2. Base-64 encoded X.509 (.CER)
-- 3. Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)
-- 4. PEM format
local encryptCert = chilkat.Cert.new()
local success = encryptCert:load_from_file("/Users/chilkat/testData/cer/acme.cer")
if not success then
    print(encryptCert.last_error_text)
    return
end

-- Tell the crypt object to use the certificate for encrypting:
crypt:add_encrypt_cert(encryptCert)

-- Encrypt a file, producing a .p7m as output.
-- The input file is unchanged, the output .p7m contains the encrypted
-- contents of the input file.
local inFile = "/Users/chilkat/testData/pdf/sample.pdf"
local outFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m"
success = crypt:ck_encrypt_file(inFile, outFile)
if not success then
    print(crypt.last_error_text)
    return
end

-- For demonstration purposes, a different instance of the object will be used
-- for decryption.
local decrypt = chilkat.Crypt2.new()

-- To decrypt, the certificate w/ private key is required.  A PFX (also known
-- as PKCS#12) is a common secure container for certs and private keys.
local pfxFilename = "/Users/chilkat/testData/pfx/acme.pfx"
local pfxPassword = "secret"

-- Tell the component to look in the PFX file for certs and private keys.
success = decrypt:add_pfx_source_file(pfxFilename, pfxPassword)
if not success then
    print(decrypt.last_error_text)
    return
end

-- Tell the decrypt object that PKI (public key encryption) is to be used
-- for decryptiong.
decrypt.crypt_algorithm = "PKI"
-- There is no need to set the Pkcs7Alg or KeyLength because this information
-- is contained within the .p7m

-- Decrypt the .p7m
inFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m"
outFile = "/Users/chilkat/testData/pdf/recovered.pdf"
success = decrypt:ck_decrypt_file(inFile, outFile)
if not success then
    print(decrypt.last_error_text)
    return
end

print("Success!")