Lua Requires Chilkat v11.0.0+

Validate JWS Using HMAC SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) using HMAC SHA-256. Lua

local chilkat = require("chilkat")

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

-- This example takes a JSON signature in compact serialization format,
-- and uses a MAC key to validate and recover the protected header and payload.

local jws = chilkat.Jws.new()

-- Set the HMAC key:
local hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
local signatureIndex = 0
jws:set_mac_key(signatureIndex, hmacKey, "base64url")

-- Load the JWS.
local jwsCompact = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"
local success = jws:load_jws(jwsCompact)

-- Validate the 1st (and only) signature at index 0..
local v = jws:validate(signatureIndex)
if v < 0 then
    -- Perhaps Chilkat was not unlocked or the trial expired..
    print("Method call failed for some other reason.")
    print(jws.last_error_text)
    return
end

if v == 0 then
    print("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.")
    return
end

-- If we get here, the signature was validated..
print("Signature validated.")

-- Recover the original content:
print("Recovered content:")
print(jws:get_payload("utf-8"))

-- Examine the protected header:

local joseHeader = chilkat.JsonObject.new()
success = jws:get_protected_h(signatureIndex, joseHeader)
if not success then
    print(jws.last_error_text)
    return
end

joseHeader.emit_compact = false

print("Protected (JOSE) header:")
print(joseHeader:emit())

-- Output:

--     Signature validated.
--     Recovered content:
--     {"iss":"joe",
--      "exp":1300819380,
--      "http://example.com/is_root":true}
--     Protected (JOSE) header:
--     {
--       "typ": "JWT",
--       "alg": "HS256"
--     }