Lua Requires Chilkat v11.0.0+

JWE using RSAES-OAEP and AES GCM

See more JSON Web Encryption (JWE) Examples

This example duplicates the example A.1 in RFC 7516 for JSON Web Encryption (JWE). Lua

local chilkat = require("chilkat")

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

local plaintext = "The true sign of intelligence is not knowledge but imagination."

-- ---------------------------------
-- A.1.1 JOSE Header
-- First build the JWE Protected Header.
-- We want to build this: {"alg":"RSA-OAEP","enc":"A256GCM"}
local jweProtHdr = chilkat.JsonObject.new()
jweProtHdr:append_string("alg", "RSA-OAEP")
jweProtHdr:append_string("enc", "A256GCM")
print("JWE Protected Header: " .. jweProtHdr:emit())
print("--")

-- ---------------------------------
-- A.1.2 Content Encryption Key
-- Note: Chilkat automatically generates the random CEK internally.
-- The application does not need to explicitly take this step.

-- ---------------------------------
-- A.1.3.  Key Encryption
-- The application should load an RSA private key from any format.
-- However, the application does not need to explicitly construct the JWE Encrypted Key.
-- Chilkat automatically does it internally.
-- The design of the Chilkat JWE API is to allow the application to create the JWE
-- after specifying the inputs.  (This is in contrast to forcing the application developer
-- to painstakingly go through each step of the JWE construction process.)

-- The specific RSA key used in the A.1 example is the following JWK:
local sbJwk = chilkat.StringBuilder.new()
sbJwk:append("{\"kty\": \"RSA\",")
sbJwk:append("\"n\": \"oahUIoWw0K0usKNuOR6H4wkf4oBUXHTxRvgb48E-BVvxkeDNjbC4he8rUW")
sbJwk:append("cJoZmds2h7M70imEVhRU5djINXtqllXI4DFqcI1DgjT9LewND8MW2Krf3S")
sbJwk:append("psk_ZkoFnilakGygTwpZ3uesH-PFABNIUYpOiN15dsQRkgr0vEhxN92i2a")
sbJwk:append("sbOenSZeyaxziK72UwxrrKoExv6kc5twXTq4h-QChLOln0_mtUZwfsRaMS")
sbJwk:append("tPs6mS6XrgxnxbWhojf663tuEQueGC-FCMfra36C9knDFGzKsNa7LZK2dj")
sbJwk:append("YgyD3JR_MB_4NUJW_TqOQtwHYbxevoJArm-L5StowjzGy-_bq6Gw\",")
sbJwk:append("\"e\": \"AQAB\",")
sbJwk:append("\"d\": \"kLdtIj6GbDks_ApCSTYQtelcNttlKiOyPzMrXHeI-yk1F7-kpDxY4-WY5N")
sbJwk:append("WV5KntaEeXS1j82E375xxhWMHXyvjYecPT9fpwR_M9gV8n9Hrh2anTpTD9")
sbJwk:append("3Dt62ypW3yDsJzBnTnrYu1iwWRgBKrEYY46qAZIrA2xAwnm2X7uGR1hghk")
sbJwk:append("qDp0Vqj3kbSCz1XyfCs6_LehBwtxHIyh8Ripy40p24moOAbgxVw3rxT_vl")
sbJwk:append("t3UVe4WO3JkJOzlpUf-KTVI2Ptgm-dARxTEtE-id-4OJr0h-K-VFs3VSnd")
sbJwk:append("VTIznSxfyrj8ILL6MG_Uv8YAu7VILSB3lOW085-4qE3DzgrTjgyQ\",")
sbJwk:append("\"p\": \"1r52Xk46c-LsfB5P442p7atdPUrxQSy4mti_tZI3Mgf2EuFVbUoDBvaRQ-")
sbJwk:append("SWxkbkmoEzL7JXroSBjSrK3YIQgYdMgyAEPTPjXv_hI2_1eTSPVZfzL0lf")
sbJwk:append("fNn03IXqWF5MDFuoUYE0hzb2vhrlN_rKrbfDIwUbTrjjgieRbwC6Cl0\",")
sbJwk:append("\"q\": \"wLb35x7hmQWZsWJmB_vle87ihgZ19S8lBEROLIsZG4ayZVe9Hi9gDVCOBm")
sbJwk:append("UDdaDYVTSNx_8Fyw1YYa9XGrGnDew00J28cRUoeBB_jKI1oma0Orv1T9aX")
sbJwk:append("IWxKwd4gvxFImOWr3QRL9KEBRzk2RatUBnmDZJTIAfwTs0g68UZHvtc\",")
sbJwk:append("\"dp\": \"ZK-YwE7diUh0qR1tR7w8WHtolDx3MZ_OTowiFvgfeQ3SiresXjm9gZ5KL")
sbJwk:append("hMXvo-uz-KUJWDxS5pFQ_M0evdo1dKiRTjVw_x4NyqyXPM5nULPkcpU827")
sbJwk:append("rnpZzAJKpdhWAgqrXGKAECQH0Xt4taznjnd_zVpAmZZq60WPMBMfKcuE\",")
sbJwk:append("\"dq\": \"Dq0gfgJ1DdFGXiLvQEZnuKEN0UUmsJBxkjydc3j4ZYdBiMRAy86x0vHCj")
sbJwk:append("ywcMlYYg4yoC4YZa9hNVcsjqA3FeiL19rk8g6Qn29Tt0cj8qqyFpz9vNDB")
sbJwk:append("UfCAiJVeESOjJDZPYHdHY8v1b-o-Z2X5tvLx-TCekf7oxyeKDUqKWjis\",")
sbJwk:append("\"qi\": \"VIMpMYbPf47dT1w_zDUXfPimsSegnMOA1zTaX7aGk_8urY6R8-ZW1FxU7")
sbJwk:append("AlWAyLWybqq6t16VFd7hQd0y6flUK4SlOydB61gwanOsXGOAOv82cHq0E3")
sbJwk:append("eL4HrtZkUuKvnPrMnsUUFlfUdybVzxyjz9JF_XyaY14ardLSjf4L_FNY\"}")

-- Load this JWK into a Chilkat private key object.
local rsaPrivKey = chilkat.PrivateKey.new()
local success = rsaPrivKey:load_jwk(sbJwk:get_as_string())
if not success then
    print(rsaPrivKey.last_error_text)
    return
end

-- The public key is used to encrypt (i.e. create the JWE),
-- and the private key is used to decrypt.
-- The RSA public key is simply a subset of the private key.  The RSA public key
-- is composed of the "n" and "e" members shown above.  These are also known as the
-- modulus and exponent.
-- We can simply get the public key object from the private key object
local rsaPubKey = chilkat.PublicKey.new()
rsaPrivKey:to_public_key(rsaPubKey)

-- ---------------------------------
-- A.1.4.  Initialization Vector
-- Chilkat automatically generates the necessary random IV internally.
-- The application does not need to do this explicitly.

-- ---------------------------------
-- A.1.5.  Additional Authenticated Data
-- The Additional Authenticated Data encryption parameter is
-- ASCII(BASE64URL(UTF8(JWE Protected Header))).
-- Again, Chilkat automatically takes care of this internally.
-- The application does not need to explicitly take this step.

-- ---------------------------------
-- A.1.6.  Content Encryption
-- Again... this step is handled by Chilkat internally.

-- ---------------------------------
-- A.1.7.  Complete Representation
-- The application need only call the Encrypt, EncryptSb, or EncryptBd method
-- return the fully assembled JWE.
-- The final representation in the Compact Serialization
-- is the string BASE64URL(UTF8(JWE Protected Header)) || '.' ||
-- BASE64URL(JWE Encrypted Key) || '.' || BASE64URL(JWE Initialization
-- Vector) || '.' || BASE64URL(JWE Ciphertext) || '.' || BASE64URL(JWE
-- Authentication Tag).

local jwe = chilkat.Jwe.new()
jwe:set_protected_header(jweProtHdr)
jwe:set_public_key(0, rsaPubKey)

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

-- Note: The RSA OAEP algorithm uses random padding bytes internally.
-- Therefore, the results will appear different each time -- even if the
-- identical plaintext is encrypted with the identical RSA key.
-- (Do not expect the appearance of the results to be the same as what
-- is published in the RFC.  However, what is published in the RFC *should*
-- be decryptable using the code that follows.)
print(strJwe)

-- Let's decrypt the JWE that was just produced.
-- Do the following to decrypt a JWE:
-- 1) Load the JWE.
-- 2) Set the private key for decryption.
-- 3) Decrypt.
local jwe2 = chilkat.Jwe.new()
success = jwe2:load_jwe(strJwe)
if not success then
    print(jwe2.last_error_text)
    return
end

-- Provide the RSA private key for decryption.
-- (The JWE was encrypted for a single recipient at index 0.)
jwe2:set_private_key(0, rsaPrivKey)

-- 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)

-- ---------------------------------------------------------------------------------
-- It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.1.7
-- because it was produced using the same RSA key.

local sbJwe = chilkat.StringBuilder.new()
sbJwe:append("eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.")
sbJwe:append("OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe")
sbJwe:append("ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb")
sbJwe:append("Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV")
sbJwe:append("mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8")
sbJwe:append("1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi")
sbJwe:append("6UklfCpIMfIjf7iGdXKHzg.")
sbJwe:append("48V1_ALb6US04U3b.")
sbJwe:append("5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji")
sbJwe:append("SdiwkIr3ajwQzaBtQD_A.")
sbJwe:append("XFBoMYUZodetZdvTiFvSkQ")

success = jwe2:load_jwe_sb(sbJwe)
if not success then
    print(jwe2.last_error_text)
    return
end

-- Provide the RSA private key for decryption.
jwe2:set_private_key(0, rsaPrivKey)

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

print(originalPlaintext)