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Lua

Set JWE Additional Authenticated Data

See more JSON Web Encryption (JWE) Examples

Demonstrates Jwe.SetAad, which sets external Additional Authenticated Data (AAD) for a JWE being encrypted, encoding the supplied text with the given charset.

Background. AAD is integrity-protected but not encrypted, binding external context to the ciphertext. The same AAD must be supplied again when decrypting.

Chilkat Lua Downloads

Lua
local chilkat = require("chilkat")

local jwe = chilkat.Jwe.new()

-- Protected header: AES key-wrap with AES-256-GCM content encryption.
local header = chilkat.JsonObject.new()
header:update_string("alg", "A256KW")
header:update_string("enc", "A256GCM")
local success = jwe:set_protected_header(header)
if not success then
    print(jwe.last_error_text)
    return
end

-- The 256-bit key-wrapping key (base64) for recipient index 0.  In production, obtain the key from a
-- secure source rather than hard-coding it.
local base64Key = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU="
success = jwe:set_wrapping_key(0, base64Key, "base64")
if not success then
    print(jwe.last_error_text)
    return
end

-- Set external Additional Authenticated Data (AAD).  The AAD is integrity-protected but not
-- encrypted, and must be supplied again when decrypting.
success = jwe:set_aad("context-info-v1", "utf-8")
if not success then
    print(jwe.last_error_text)
    return
end

local sbContent = chilkat.StringBuilder.new()
sbContent:append("This is the secret content.")
local sbJwe = chilkat.StringBuilder.new()
success = jwe:encrypt_sb(sbContent, "utf-8", sbJwe)
if not success then
    print(jwe.last_error_text)
    return
end

print(sbJwe:get_as_string())