Lua Requires Chilkat v9.5.0.67+

Example for both AES-128 and ChaCha20 to Encrypt Binary Data

See more Encryption Examples

Demonstrates the use of the EncryptBd and DecryptBd methods to encrypt/decrypt binary bytes. Lua

local chilkat = require("chilkat")

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

-- Load a small JPG file to be encrypted/decrypted.
local jpgBytes = chilkat.BinData.new()
local success = jpgBytes:load_file("qa_data/jpg/starfish.jpg")
if not success then
    print("Failed to load JPG file.")
    return
end

-- Show the unencrypted JPG bytes in Base64 format.
-- (The "base64" encoding emits a single line of base64, whereas
-- "base64_mime" will emit multi-line base64 as it would appear
-- in MIME.)
print(jpgBytes:get_encoded("base64_mime"))

-- Sample base64_mime JPG data:

--     /9j/4AAQSkZJRgABAgEASABIAAD/7Q18UGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAAAAEA
--     AQBIAAAAAQABOEJJTQPzAAAAAAAIAAAAAAAAAAE4QklNBAoAAAAAAAEAADhCSU0nEAAAAAAACgAB
--     AAAAAAAAAAI4QklNA/UAAAAAAEgAL2ZmAAEAbGZmAAYAAAAAAAEAL2ZmAAEAoZmaAAYAAAAAAAEA
--     MgAAAAEAWgAAAAYAAAAAAAEANQAAAAEALQAAAAYAAAAAAAE4QklNBBQAAAAAAAQAAAABOEJJTQQM
--     ...

local crypt = chilkat.Crypt2.new()

-- Specify the encryption to be used.
-- First we'll do AES-128 CBC
crypt.crypt_algorithm = "aes"
crypt.cipher_mode = "cbc"
crypt.key_length = 128

local ivHex = "000102030405060708090A0B0C0D0E0F"
crypt:set_encoded_iv(ivHex, "hex")

local keyHex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
crypt:set_encoded_key(keyHex, "hex")

-- Do the in-place 128-bit AES CBC encryption.
-- The contents of jpgBytes are replaced with the encrypted bytes.
success = crypt:encrypt_bd(jpgBytes)
if not success then
    print(crypt.last_error_text)
    return
end

-- Examine the JPG bytes again.  The bytes should be different because they are encrypted:
print(jpgBytes:get_encoded("base64_mime"))

-- Sample base64_mime encrypted JPG data:

--     sbz0babt1WCkQf5xKMdg/baZAcUBO5GVUUDF2BjVqmd+HrqKN+t6hAcqakL/bdo0q9hYmow0Tp1e
--     AQ9V9DOiifQUZqWVkR+kL/c45bq8JGFDvgNl0djPt+yYhV789IB/fPH0upx+/ad++WNOlv1IxGMr
--     Y1x1oERU/IsiEzafUJdI4kZ6FQo2IPGMF/Rm1h79I7hP1yYUFxvJyz+PzaySAUH1nLsNHyDVY5VY
--     O90aH3steRSYbz8C8UF9wQ3qqEIXQNnnixvoNDnmHyY39VoVBI5F6rnPwYDfAk2t8tmuryFqvwAu
--     ...

-- Decrypt to restore back to the original:
success = crypt:decrypt_bd(jpgBytes)
if not success then
    print(crypt.last_error_text)
    return
end

print(jpgBytes:get_encoded("base64_mime"))

--     /9j/4AAQSkZJRgABAgEASABIAAD/7Q18UGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAAAAEA
--     AQBIAAAAAQABOEJJTQPzAAAAAAAIAAAAAAAAAAE4QklNBAoAAAAAAAEAADhCSU0nEAAAAAAACgAB
--     AAAAAAAAAAI4QklNA/UAAAAAAEgAL2ZmAAEAbGZmAAYAAAAAAAEAL2ZmAAEAoZmaAAYAAAAAAAEA
--     MgAAAAEAWgAAAAYAAAAAAAEANQAAAAEALQAAAAYAAAAAAAE4QklNBBQAAAAAAAQAAAABOEJJTQQM
--     ...

-- ----------------------------------------------------------------------------------
-- To do chacha20 encryption, just change the settings:

crypt.crypt_algorithm = "chacha20"
crypt.key_length = 256
-- The initial count is the initial block counter for the chacha20 algorithm.
-- It can be any integer, but must be set to the same when decrypting.
crypt.initial_count = 22

success = crypt:encrypt_bd(jpgBytes)
-- jpgBytes now contains chacha20 encrypted bytes.

success = crypt:decrypt_bd(jpgBytes)
-- jpgBytes is now restored back to the original unencrypted by bytes.

-- Save the bytes to a file..
success = jpgBytes:write_file("qa_output/starfish.jpg")

print("Success.")