(PureBasic) How to Generate a JSON Web Key (JWK)

Demonstrates how to generate the following types of JSON Web Keys:

• RSA key pair
• EC key pair
• Octet sequence key (HMAC-256)
• 192-bit AES GCM key

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

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IncludeFile "CkJsonObject.pb"
IncludeFile "CkEcc.pb"
IncludeFile "CkPrivateKey.pb"
IncludeFile "CkPrng.pb"
IncludeFile "CkCrypt2.pb"
IncludeFile "CkRsa.pb"

Procedure ChilkatExample()

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

    ; ----------------------------------------------
    ; Generate an RSA key pair in JWK format.
    ; (Examples for generating other key types are shown below...)
    rsa.i = CkRsa::ckCreate()
    If rsa.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkRsa::ckGenerateKey(rsa,2048)
    rsaKey.i = CkRsa::ckExportPrivateKeyObj(rsa)
    rsaJwkStr.s = CkPrivateKey::ckGetJwk(rsaKey)

    ; The string returned is the most compact possible, and therefore it is not
    ; very readable.  To pretty-print, load into a JSON object and emit..
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::setCkEmitCompact(json, 0)
    CkJsonObject::ckLoad(json,rsaJwkStr)
    Debug CkJsonObject::ckEmit(json)

    CkPrivateKey::ckDispose(rsaKey)

    ; Sample RSA JWK:

    ; { 
    ;   "kty": "RSA",
    ;   "n": "6w1Xpof7gKmytJ3yc_yjI5_K3MvVXnBYBDy5Oh2W6Xqu_fOl3W18SjS2AU5xJrTHlB_j84yQjPyXJh_ixjACK4K4dCSYqlLmn3R7QJ84vnHLIEkqwUICqOHdCBjK5xhMrdZxIhuNlJzbARY-3u9RqjsT3HYTjA6JNHUWTYBBRou4gYGm4cJgvX4uexdikqxnze014RmZMaOV_4MR--WL4G8QfNJ2pRBEXQeKyije89H6M5oTSK7KZqFTIqu9hwNtx2oGpGAIcS0Jv5xVl-hDtwXZNwQJaOxMzLw1nwnb2kMliJa67EabQFrQY_xthQNsfzcHJJlpqYiMprW8wRkzmQ",
    ;   "e": "AQAB",
    ;   "d": "1_bnXMw-SeYhmxAwb19lqVqtMpdaES5ZwHLmoT4EpbsiQ5T1BfENrMSnoaWoEy8w3Kk8cU7qlY-TdOUBIKWFqOKvhY8GciA_Y6zLfgGNSnYVczGmxfBXr0HvKvxUmWZbNbH9OqBkQnKoSmRdGcp7l1Q2mG4o4ZuNdxRJjKXV0_DTrNLUJzst0hsfoZ6mWUrQcn39XGvvLjz9ySS-DYGI1vli3ayx8jVNuw0rU8UXVs9WmPQLvZO_ZDMhoLEeKsdejnNkUNPAUjqxcSOZRojt4BfCmbt-_1slFb0NsoaqnDVZGezd9J9ocxGuyIWHAJu9GGZEcdaFyiDDs_WA1IS_fQ",
    ;   "p": "9dU8f6yOklRcpV6ayVMKpyQ6AMuBTF3rZmB498eAvvTkVG1-upm8IkikTVNpPjEalc82Sxuq8oF4N5x1-F33sgVEoCZG-1WFZTn-rnPnXSALES9hqSaVYEwnh61EiY8ckjBVr9jD2nL1JKdbfgVVeo69-9PdjnKYYDVL8eLNPwM",
    ;   "q": "9MX2sW0GyaOsZ86AYe3eG2ZgcgKHvhJa573gih5Jvi2e-Nv-L0EVK29_DA7n0Pjm-gl9zVAsGsMMkphJyEF9QgyUlJ-59XLqWnECS5gO6WZdtHrJxVvcO-_AOrLIxeYnYcwhmaVaxs_UEpqGzupKHCWgf4cfXe49lrIsqGKH4jM",
    ;   "dp": "IQgj9uvSxGq9gCL0HXUhC1Bc0tqFZyN_i-QOnQybig0R2R5VVvFtTBYCrbk1fPvQHK0ZGIKBN9CZvK8zUsodjDgU_ofmJcNaBz4BsKM2RVcW5Zo-PyJGFAhnj12CxhEKv8Hq4ZP4zROBSQmLy6Uf1TX05S-Up51SSCshJ0FYXs0",
    ;   "dq": "RijsMiUfGfL5OvP85pUI4e-xW1yQThHyzpQlZVGTL5jiBVEBhcfw6ndWAj3Pgp2ljyvjTFNboPwhgW93Tpg-8AytFgDGi605sVzNHJ_kPlBiMZY0eYaAFQn-npSaaecziJu7UdAMugneLsruMycCwRij7Ynsmr7sFmLR3B4J9vM",
    ;   "qi": "jZE-a1pa8YjflpCSH5oqp1f6f6I6-hpZcLdamLCoAcjVSIPk86gtXtOFES4411-DqYzYIZM6B_g_SRYY6JpKAOuZ40mmMTlnIEoVf8BHiGl3g6bBAiN1yQGXrwXJsg2OYnocyRA-xWNdcMSSFA52SwEdar2Mmw29qVzxtC1QbpA"
    ; }

    ; ----------------------------------------------
    ; Generate an EC P-256 key pair in JWK format

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

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

    ecKey.i = CkEcc::ckGenEccKey(ecc,"P-256",prng)
    If CkEcc::ckLastMethodSuccess(ecc) <> 1
        Debug CkEcc::ckLastErrorText(ecc)
        CkRsa::ckDispose(rsa)
        CkJsonObject::ckDispose(json)
        CkPrng::ckDispose(prng)
        CkEcc::ckDispose(ecc)
        ProcedureReturn
    EndIf

    ecJwkStr.s = CkPrivateKey::ckGetJwk(ecKey)
    CkJsonObject::ckLoad(json,ecJwkStr)
    Debug CkJsonObject::ckEmit(json)

    CkPrivateKey::ckDispose(ecKey)

    ; Sample EC JWK Key:
    ; { 
    ;   "kty": "EC",
    ;   "crv": "P-256",
    ;   "x": "tDeeYABgKEAbWicYPCEEI8sP4SRIhHKcHDW7VqrB4LA",
    ;   "y": "J08HOoIZ0rX2Me3bNFZUltfxIk1Hrc8FsLu8VaSxsMI",
    ;   "d": "-bqt1T0wNAN8sP5ruycQZRVlMlt3V_dSwlJ60xAX5io"
    ; }

    ; ----------------------------------------------
    ; Octet sequence keys are intended for representing secret keys, such as HMAC keys and AES keys.

    ; We'll use crypt to generate a random UUID..
    crypt.i = CkCrypt2::ckCreate()
    If crypt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; AES and HMAC keys are simply random arrays of bytes
    ; For these, we can just build the JSON directly,
    ; with the help of the PRNG object.

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

    CkJsonObject::setCkEmitCompact(jwkHmac, 0)

    ; Generate a 256-bit HMAK key (32 bytes)
    CkJsonObject::ckAppendString(jwkHmac,"kty","oct")
    ; Give the key an optional ID, which can be anything, even strings as simple as "1", "2", etc.
    CkJsonObject::ckAppendString(jwkHmac,"kid",CkCrypt2::ckGenerateUuid(crypt))
    ; Indicate the intended key alg (optional)
    CkJsonObject::ckAppendString(jwkHmac,"alg","HS256")
    ; Generate the actual key bytes
    CkJsonObject::ckAppendString(jwkHmac,"k",CkPrng::ckGenRandom(prng,32,"base64url"))

    Debug CkJsonObject::ckEmit(jwkHmac)

    ; Sample HMAC-256 JWK:

    ; { 
    ;   "kty": "oct",
    ;   "kid": "06c2515d-41fb-e436-e405-3abb361f5f7a",
    ;   "alg": "HS256",
    ;   "k": "wR32w7yiMe5Lhb1vkW2koBpoMxpXTFYuxOYCCIEKjdE"
    ; }

    ; ----------------------------------------------
    ; Now generate a 192-bit (24 byte) key that could be used with AES192GCM

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

    CkJsonObject::setCkEmitCompact(jwkAes, 0)

    CkJsonObject::ckAppendString(jwkAes,"kty","oct")
    CkJsonObject::ckAppendString(jwkAes,"kid","2")
    CkJsonObject::ckAppendString(jwkAes,"k",CkPrng::ckGenRandom(prng,24,"base64url"))

    Debug CkJsonObject::ckEmit(jwkAes)

    ; Sample AES key:
    ; { 
    ;   "kty": "oct",
    ;   "kid": "2",
    ;   "k": "akAkq-L_ZTZ6-tEIhDUMtU2ENhsEgL-p"
    ; }


    CkRsa::ckDispose(rsa)
    CkJsonObject::ckDispose(json)
    CkPrng::ckDispose(prng)
    CkEcc::ckDispose(ecc)
    CkCrypt2::ckDispose(crypt)
    CkJsonObject::ckDispose(jwkHmac)
    CkJsonObject::ckDispose(jwkAes)


    ProcedureReturn
EndProcedure