Lua Requires Chilkat v9.5.0.67+

AES and CHACHA20 Encrypt/Decrypt Text

See more Encryption Examples

Demonstrates the use of the EncryptSb and DecryptSb methods to encrypt/decrypt the contents of StringBuilder objects. Lua

local chilkat = require("chilkat")

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

-- First build a string to be encrypted
local sb = chilkat.StringBuilder.new()
local i = 1
while i < 10 do
    sb:append_int(i)
    sb:append(" the quick brown fox jumped over the lazy dog.\r\n")
    i = i + 1
end

print(sb:get_as_string())

-- The string to be encrypted looks like this:

-- 1 the quick brown fox jumped over the lazy dog.
-- 2 the quick brown fox jumped over the lazy dog.
-- 3 the quick brown fox jumped over the lazy dog.
-- 4 the quick brown fox jumped over the lazy dog.
-- 5 the quick brown fox jumped over the lazy dog.
-- 6 the quick brown fox jumped over the lazy dog.
-- ...

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")

-- When EncryptSb is called, the contents of the source (sb)
-- remains unmodified.  The encrypted bytes are written into bdEncrypted.
-- If bdEncrypted already contained data, it is replaced with the encrypted bytes.
local bdEncrypted = chilkat.BinData.new()
local success = crypt:encrypt_sb(sb, bdEncrypted)
if not success then
    print(crypt.last_error_text)
    return
end

-- Examine the encrypted bytes:
print(bdEncrypted:get_encoded("base64_mime"))

-- Sample encrypted data:

-- 0DdNZ22ckMMJBiaKhAu3wUEfh16XW356NIUsDmNs/xwbHe/p1201OmpfzwXwKktkAefu2pckrBgC
-- df+1w8lRo+KAy5n5wlAgMGM/UrsVJsp0BmDPk1vaxKrmrGpSXOVCQs1n2+0atIs5YLiOG+Va3+Mi
-- EQNb4YK7bNMmvt0++irBxTiGnkx/RncfKwgkbBUpl2x7yV13MW6lapDT6Md0DKAMsTXFJYGeIdEf
-- g2uxDDQzI5gUOUHTMrXQ8paD/K76KKB9Jpp/kAM9z8g/d8KUmuphA7KI64d38xsgOmcITlbhlCQ2
-- PDkcU6RRzX0FUTUSMgQukhy0jkLZEjHX9poKJD+iJTOkcQUC3OqR9hKhSrvIgJN4lxdR71MheOoQ
-- 2wmvRdq+agTWWh333Vmb6J6yDV79aSpnqEDrA8Ks7Xzciol0gve91+JtVJlJKjWwEzWEU8GxF7Q8
-- eaWI70lsC5nTLGcbqgKu6gzkzHlHyHaE2FAQA/d5I2dvfsAYUQCza0Zdyw8mmTtHhlP2Tfxj1uPv
-- H4Q7BGuKnx3SWT2CnpbX4091w7KzLAztrbFBo/Tf9w8ZpgTK9k1ryfW9/xnk6rW6iQ==

-- Decrypt to restore back to the original:
local sbOriginal = chilkat.StringBuilder.new()
success = crypt:decrypt_sb(bdEncrypted, sbOriginal)
if not success then
    print(crypt.last_error_text)
    return
end

-- Examine the original data:
print(sbOriginal:get_as_string())

-- ----------------------------------------------------------------------------------
-- 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

-- EncryptSb completely replaces the contents of bdEncrypted.
success = crypt:encrypt_sb(sb, bdEncrypted)

-- However.. DecryptSb appends the decrypted text to whatever may
-- have already existed within sbOriginal.
success = crypt:decrypt_sb(bdEncrypted, sbOriginal)

print("----")
print("The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt.")
print(sbOriginal:get_as_string())
print("Success.")