(PureBasic) Load ECC Public Key from JWK Format (JSON Web Key)

Demonstrates how to load an ECC public key from JWK (JSON Web Key) format.

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

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IncludeFile "CkPublicKey.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    ; Note: This example requires Chilkat v9.5.0.66 or later.
    success.i

    ; First build a JWK sample to load..
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(json,"kty","EC")
    CkJsonObject::ckUpdateString(json,"crv","P-256")
    CkJsonObject::ckUpdateString(json,"x","oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE")
    CkJsonObject::ckUpdateString(json,"y","vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU")

    ; The JSON contains the following:
    ; { 
    ;   "kty": "EC",
    ;   "crv": "P-256",
    ;   "x": "oBUyo8CQAFPeYPvv78ylh5MwFZjTCLQeb042TjiMJxE",
    ;   "y": "vvQyxZkUjJQUPU_0bCy3Pj5qQdfu8jwEfqEeYGZ95CU",
    ; }

    ; Note: The JSON can contain other members, such as "use", "kid", or anything else.  These will be ignored.
    CkJsonObject::setCkEmitCompact(json, 0)

    ; Show the JWK string to be loaded:
    jwkStr.s = CkJsonObject::ckEmit(json)

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

    ; The LoadFromString method will automatically detect the format.
    success = CkPublicKey::ckLoadFromString(pubKey,jwkStr)
    If success <> 1
        Debug CkPublicKey::ckLastErrorText(pubKey)
        CkJsonObject::ckDispose(json)
        CkPublicKey::ckDispose(pubKey)
        ProcedureReturn
    EndIf

    ; OK.. the JWK is loaded.  It can be used in whatever way desired...

    ; The key can be retrieved in any other format, such as XML or PEM..
    Debug CkPublicKey::ckGetXml(pubKey)

    ; XML output:
    ; <ECCPublicKey curve="secp256r1" 
    ;    x="A01532A3C0900053DE60FBEFEFCCA58793301598D308B41E6F4E364E388C2711" 
    ;    y="BEF432C599148C94143D4FF46C2CB73E3E6A41D7EEF23C047EA11E60667DE425">
    ;    MIIBSzCCAQMGByqGSM49AgEwgfcCAQEwLAYHKoZIzj0BAQIhAP////8AAAABAAAAAAAAAAAAAAAA////////////////MFsEIP////8AAAABAAAAAAAAAAAAAAAA///////////////8BCBaxjXYqjqT57PrvVV2mIa8ZR0GsMxTsPY7zjw+J9JgSwMVAMSdNgiG5wSTamZ44ROdJreBn36QBEEEaxfR8uEsQkf4vOblY6RA8ncDfYEt6zOg9KE5RdiYwpZP40Li/hp/m47n60p8D54WK84zV2sxXs7LtkBoN79R9QIhAP////8AAAAA//////////+85vqtpxeehPO5ysL8YyVRAgEBA0IABKAVMqPAkABT3mD77+/MpYeTMBWY0wi0Hm9ONk44jCcRvvQyxZkUjJQUPU/0bCy3Pj5qQdfu8jwEfqEeYGZ95CU=
    ; </ECCPublicKey>

    ; Choose PCKS1 or PCKS8 PEM format..
    bPreferPkcs1.i = 0
    Debug CkPublicKey::ckGetPem(pubKey,bPreferPkcs1)

    ; PEM output
    ; -----BEGIN PUBLIC KEY-----
    ; MIIBSzCCAQMGByqGSM49AgEwgfcCAQEwLAYHKoZIzj0BAQIhAP////8AAAABAAAA
    ; AAAAAAAAAAAA////////////////MFsEIP////8AAAABAAAAAAAAAAAAAAAA////
    ; ///////////8BCBaxjXYqjqT57PrvVV2mIa8ZR0GsMxTsPY7zjw+J9JgSwMVAMSd
    ; NgiG5wSTamZ44ROdJreBn36QBEEEaxfR8uEsQkf4vOblY6RA8ncDfYEt6zOg9KE5
    ; RdiYwpZP40Li/hp/m47n60p8D54WK84zV2sxXs7LtkBoN79R9QIhAP////8AAAAA
    ; //////////+85vqtpxeehPO5ysL8YyVRAgEBA0IABKAVMqPAkABT3mD77+/MpYeT
    ; MBWY0wi0Hm9ONk44jCcRvvQyxZkUjJQUPU/0bCy3Pj5qQdfu8jwEfqEeYGZ95CU=
    ; -----END PUBLIC KEY-----


    CkJsonObject::ckDispose(json)
    CkPublicKey::ckDispose(pubKey)


    ProcedureReturn
EndProcedure