Lua

ARC4 Encryption (ARCFOUR)

See more Encryption Examples

ARC4 (ARCFOUR) encryption. The Chilkat encryption component supports the ARC4 streaming encryption algorithm. Lua

local chilkat = require("chilkat")

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

local crypt = chilkat.Crypt2.new()

-- Set the encryption algorithm = "arc4"
crypt.crypt_algorithm = "arc4"

-- KeyLength may range from 1 byte to 256 bytes.
-- (i.e. 8 bits to 2048 bits)
-- ARC4 key sizes are typically in the range of
-- 40 to 128 bits.
-- The KeyLength property is specified in bits:
crypt.key_length = 128

-- Note: The PaddingScheme and CipherMode properties
-- do not apply w/ ARC4.  ARC4 does not encrypt in blocks --
-- it is a streaming encryption algorithm. The number of output bytes
-- is exactly equal to the number of input bytes.

-- EncodingMode specifies the encoding of the output for
-- encryption, and the input for decryption.
-- It may be "hex", "url", "base64", or "quoted-printable".
crypt.encoding_mode = "hex"

-- Note: ARC4 does not utilize initialization vectors.  IV's only
-- apply to block encryption algorithms.

-- The secret key must equal the size of the key.
-- For 128-bit encryption, the binary secret key is 16 bytes.
local keyHex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
crypt:set_encoded_key(keyHex, "hex")

-- Encrypt a string...
-- The output length is exactly equal to the input.  In this
-- example, the input string is 44 chars (ANSI bytes) so the
-- output is 44 bytes -- and when hex encoded results in an
-- 88-char string (2 chars per byte for the hex encoding).
local encStr = crypt:encrypt_string_enc("The quick brown fox jumps over the lazy dog.")
print(encStr)

-- Now decrypt:
local decStr = crypt:decrypt_string_enc(encStr)
print(decStr)