(PureBasic) JWE using RSAES-OAEP and AES GCM

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

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkJwe.pb"
IncludeFile "CkPrivateKey.pb"
IncludeFile "CkPublicKey.pb"

Procedure ChilkatExample()

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

    ; Note: This example requires Chilkat v9.5.0.66 or greater.

    success.i
    plaintext.s = "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"}
    jweProtHdr.i = CkJsonObject::ckCreate()
    If jweProtHdr.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckAppendString(jweProtHdr,"alg","RSA-OAEP")
    CkJsonObject::ckAppendString(jweProtHdr,"enc","A256GCM")
    Debug "JWE Protected Header: " + CkJsonObject::ckEmit(jweProtHdr)
    Debug "--"

    ; ---------------------------------
    ; 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:
    sbJwk.i = CkStringBuilder::ckCreate()
    If sbJwk.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbJwk,"{" + Chr(34) + "kty" + Chr(34) + ": " + Chr(34) + "RSA" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "n" + Chr(34) + ": " + Chr(34) + "oahUIoWw0K0usKNuOR6H4wkf4oBUXHTxRvgb48E-BVvxkeDNjbC4he8rUW")
    CkStringBuilder::ckAppend(sbJwk,"cJoZmds2h7M70imEVhRU5djINXtqllXI4DFqcI1DgjT9LewND8MW2Krf3S")
    CkStringBuilder::ckAppend(sbJwk,"psk_ZkoFnilakGygTwpZ3uesH-PFABNIUYpOiN15dsQRkgr0vEhxN92i2a")
    CkStringBuilder::ckAppend(sbJwk,"sbOenSZeyaxziK72UwxrrKoExv6kc5twXTq4h-QChLOln0_mtUZwfsRaMS")
    CkStringBuilder::ckAppend(sbJwk,"tPs6mS6XrgxnxbWhojf663tuEQueGC-FCMfra36C9knDFGzKsNa7LZK2dj")
    CkStringBuilder::ckAppend(sbJwk,"YgyD3JR_MB_4NUJW_TqOQtwHYbxevoJArm-L5StowjzGy-_bq6Gw" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "e" + Chr(34) + ": " + Chr(34) + "AQAB" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "d" + Chr(34) + ": " + Chr(34) + "kLdtIj6GbDks_ApCSTYQtelcNttlKiOyPzMrXHeI-yk1F7-kpDxY4-WY5N")
    CkStringBuilder::ckAppend(sbJwk,"WV5KntaEeXS1j82E375xxhWMHXyvjYecPT9fpwR_M9gV8n9Hrh2anTpTD9")
    CkStringBuilder::ckAppend(sbJwk,"3Dt62ypW3yDsJzBnTnrYu1iwWRgBKrEYY46qAZIrA2xAwnm2X7uGR1hghk")
    CkStringBuilder::ckAppend(sbJwk,"qDp0Vqj3kbSCz1XyfCs6_LehBwtxHIyh8Ripy40p24moOAbgxVw3rxT_vl")
    CkStringBuilder::ckAppend(sbJwk,"t3UVe4WO3JkJOzlpUf-KTVI2Ptgm-dARxTEtE-id-4OJr0h-K-VFs3VSnd")
    CkStringBuilder::ckAppend(sbJwk,"VTIznSxfyrj8ILL6MG_Uv8YAu7VILSB3lOW085-4qE3DzgrTjgyQ" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "p" + Chr(34) + ": " + Chr(34) + "1r52Xk46c-LsfB5P442p7atdPUrxQSy4mti_tZI3Mgf2EuFVbUoDBvaRQ-")
    CkStringBuilder::ckAppend(sbJwk,"SWxkbkmoEzL7JXroSBjSrK3YIQgYdMgyAEPTPjXv_hI2_1eTSPVZfzL0lf")
    CkStringBuilder::ckAppend(sbJwk,"fNn03IXqWF5MDFuoUYE0hzb2vhrlN_rKrbfDIwUbTrjjgieRbwC6Cl0" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "q" + Chr(34) + ": " + Chr(34) + "wLb35x7hmQWZsWJmB_vle87ihgZ19S8lBEROLIsZG4ayZVe9Hi9gDVCOBm")
    CkStringBuilder::ckAppend(sbJwk,"UDdaDYVTSNx_8Fyw1YYa9XGrGnDew00J28cRUoeBB_jKI1oma0Orv1T9aX")
    CkStringBuilder::ckAppend(sbJwk,"IWxKwd4gvxFImOWr3QRL9KEBRzk2RatUBnmDZJTIAfwTs0g68UZHvtc" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "dp" + Chr(34) + ": " + Chr(34) + "ZK-YwE7diUh0qR1tR7w8WHtolDx3MZ_OTowiFvgfeQ3SiresXjm9gZ5KL")
    CkStringBuilder::ckAppend(sbJwk,"hMXvo-uz-KUJWDxS5pFQ_M0evdo1dKiRTjVw_x4NyqyXPM5nULPkcpU827")
    CkStringBuilder::ckAppend(sbJwk,"rnpZzAJKpdhWAgqrXGKAECQH0Xt4taznjnd_zVpAmZZq60WPMBMfKcuE" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "dq" + Chr(34) + ": " + Chr(34) + "Dq0gfgJ1DdFGXiLvQEZnuKEN0UUmsJBxkjydc3j4ZYdBiMRAy86x0vHCj")
    CkStringBuilder::ckAppend(sbJwk,"ywcMlYYg4yoC4YZa9hNVcsjqA3FeiL19rk8g6Qn29Tt0cj8qqyFpz9vNDB")
    CkStringBuilder::ckAppend(sbJwk,"UfCAiJVeESOjJDZPYHdHY8v1b-o-Z2X5tvLx-TCekf7oxyeKDUqKWjis" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJwk,Chr(34) + "qi" + Chr(34) + ": " + Chr(34) + "VIMpMYbPf47dT1w_zDUXfPimsSegnMOA1zTaX7aGk_8urY6R8-ZW1FxU7")
    CkStringBuilder::ckAppend(sbJwk,"AlWAyLWybqq6t16VFd7hQd0y6flUK4SlOydB61gwanOsXGOAOv82cHq0E3")
    CkStringBuilder::ckAppend(sbJwk,"eL4HrtZkUuKvnPrMnsUUFlfUdybVzxyjz9JF_XyaY14ardLSjf4L_FNY" + Chr(34) + "}")

    ; Load this JWK into a Chilkat private key object.
    rsaPrivKey.i = CkPrivateKey::ckCreate()
    If rsaPrivKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPrivateKey::ckLoadJwk(rsaPrivKey,CkStringBuilder::ckGetAsString(sbJwk))
    If success <> 1
        Debug CkPrivateKey::ckLastErrorText(rsaPrivKey)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwk)
        CkPrivateKey::ckDispose(rsaPrivKey)
        ProcedureReturn
    EndIf

    ; 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
    rsaPubKey.i = CkPrivateKey::ckGetPublicKey(rsaPrivKey)

    ; ---------------------------------
    ; 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).

    jwe.i = CkJwe::ckCreate()
    If jwe.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJwe::ckSetProtectedHeader(jwe,jweProtHdr)
    CkJwe::ckSetPublicKey(jwe,0,rsaPubKey)
    CkPublicKey::ckDispose(rsaPubKey)

    strJwe.s = CkJwe::ckEncrypt(jwe,plaintext,"utf-8")
    If CkJwe::ckLastMethodSuccess(jwe) <> 1
        Debug CkJwe::ckLastErrorText(jwe)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwk)
        CkPrivateKey::ckDispose(rsaPrivKey)
        CkJwe::ckDispose(jwe)
        ProcedureReturn
    EndIf

    ; 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.)
    Debug 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.
    jwe2.i = CkJwe::ckCreate()
    If jwe2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJwe::ckLoadJwe(jwe2,strJwe)
    If success <> 1
        Debug CkJwe::ckLastErrorText(jwe2)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwk)
        CkPrivateKey::ckDispose(rsaPrivKey)
        CkJwe::ckDispose(jwe)
        CkJwe::ckDispose(jwe2)
        ProcedureReturn
    EndIf

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

    ; Decrypt.
    originalPlaintext.s = CkJwe::ckDecrypt(jwe2,0,"utf-8")
    If CkJwe::ckLastMethodSuccess(jwe2) <> 1
        Debug CkJwe::ckLastErrorText(jwe2)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwk)
        CkPrivateKey::ckDispose(rsaPrivKey)
        CkJwe::ckDispose(jwe)
        CkJwe::ckDispose(jwe2)
        ProcedureReturn
    EndIf

    Debug "original text: "
    Debug 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.

    sbJwe.i = CkStringBuilder::ckCreate()
    If sbJwe.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbJwe,"eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.")
    CkStringBuilder::ckAppend(sbJwe,"OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe")
    CkStringBuilder::ckAppend(sbJwe,"ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb")
    CkStringBuilder::ckAppend(sbJwe,"Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV")
    CkStringBuilder::ckAppend(sbJwe,"mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8")
    CkStringBuilder::ckAppend(sbJwe,"1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi")
    CkStringBuilder::ckAppend(sbJwe,"6UklfCpIMfIjf7iGdXKHzg.")
    CkStringBuilder::ckAppend(sbJwe,"48V1_ALb6US04U3b.")
    CkStringBuilder::ckAppend(sbJwe,"5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji")
    CkStringBuilder::ckAppend(sbJwe,"SdiwkIr3ajwQzaBtQD_A.")
    CkStringBuilder::ckAppend(sbJwe,"XFBoMYUZodetZdvTiFvSkQ")

    success = CkJwe::ckLoadJweSb(jwe2,sbJwe)
    If success <> 1
        Debug CkJwe::ckLastErrorText(jwe2)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwk)
        CkPrivateKey::ckDispose(rsaPrivKey)
        CkJwe::ckDispose(jwe)
        CkJwe::ckDispose(jwe2)
        CkStringBuilder::ckDispose(sbJwe)
        ProcedureReturn
    EndIf

    ; Provide the RSA private key for decryption.
    CkJwe::ckSetPrivateKey(jwe2,0,rsaPrivKey)

    ; Decrypt.
    originalPlaintext = CkJwe::ckDecrypt(jwe2,0,"utf-8")
    If CkJwe::ckLastMethodSuccess(jwe2) <> 1
        Debug CkJwe::ckLastErrorText(jwe2)
        CkJsonObject::ckDispose(jweProtHdr)
        CkStringBuilder::ckDispose(sbJwk)
        CkPrivateKey::ckDispose(rsaPrivKey)
        CkJwe::ckDispose(jwe)
        CkJwe::ckDispose(jwe2)
        CkStringBuilder::ckDispose(sbJwe)
        ProcedureReturn
    EndIf

    Debug originalPlaintext


    CkJsonObject::ckDispose(jweProtHdr)
    CkStringBuilder::ckDispose(sbJwk)
    CkPrivateKey::ckDispose(rsaPrivKey)
    CkJwe::ckDispose(jwe)
    CkJwe::ckDispose(jwe2)
    CkStringBuilder::ckDispose(sbJwe)


    ProcedureReturn
EndProcedure