Lua

JWE using A256GCMKW

See more JSON Web Encryption (JWE) Examples

This example demonstrates creating a JCE with AES GCM key wrap. Lua

local chilkat = require("chilkat")

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

local plaintext = "My text to enrypt"

local jwe = chilkat.Jwe.new()

-- First build the JWE Protected Header:

--         {
--             "alg": "A256GCMKW",
--             "kid": "18ec08e1-bfa9-4d95-b205-2b4dd1d4321d",
--             "tag": "kfPduVQ3T3H6vnewt--ksw",
--             "iv": "KkYT0GX_2jHlfqN_",
--             "enc": "A128CBC-HS256"
--         }

local jweProtHdr = chilkat.JsonObject.new()
jweProtHdr:append_string("alg", "A256GCMKW")
-- kid is optional
jweProtHdr:append_string("kid", "18ec08e1-bfa9-4d95-b205-2b4dd1d4321d")
-- tag is optional
jweProtHdr:append_string("tag", "kfPduVQ3T3H6vnewt--ksw")
jweProtHdr:append_string("enc", "A256GCM")
-- the iv should be 16 random chars.
local prng = chilkat.Prng.new()
jweProtHdr:append_string("iv", prng:random_string(16, true, true, true))
jwe:set_protected_header(jweProtHdr)

print("JWE Protected Header: " .. jweProtHdr:emit())
print("--")

-- Given that we have 256-bit AES, our key should be 32 bytes.
-- The ascii string here is 32 bytes, therefore the 2nd arg is "ascii" to use these
-- ascii chars directly as the key.
local aesWrappingKey = "2baf4f730f5e4542b428593ef9cceb0e"
jwe:set_wrapping_key(0, aesWrappingKey, "ascii")

-- Encrypt and return the JWE:
local strJwe = jwe:encrypt(plaintext, "utf-8")
if not jwe.last_method_success then
    print(jwe.last_error_text)
    return
end

-- Show the JWE we just created:
print(strJwe)

-- Decrypt the JWE that was just produced.
-- 1) Load the JWE.
-- 2) Set the AES wrapping key.
-- 3) Decrypt.
local jwe2 = chilkat.Jwe.new()
local success = jwe2:load_jwe(strJwe)
if not success then
    print(jwe2.last_error_text)
    return
end

-- Set the AES wrap key.  Important to use "ascii"
jwe2:set_wrapping_key(0, aesWrappingKey, "ascii")

-- Decrypt.
local originalPlaintext = jwe2:decrypt(0, "utf-8")
if not jwe2.last_method_success then
    print(jwe2.last_error_text)
    return
end

print("original text: ")
print(originalPlaintext)