(PureBasic) JWE using ECDH-ES, BP-256, A256GCM

See more JSON Web Encryption (JWE) Examples

Create a JWE with the following header:

	{
	  "alg": "ECDH-ES",
	  "enc": "A256GCM",
	  "exp": 1621957030,
	  "cty": "NJWT",
	  "epk": {
	    "kty": "EC",
	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
	    "crv": "BP-256"
	  }
	}

Note: This example requires Chilkat v9.5.0.87 or greater.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkJwt.pb"
IncludeFile "CkJwe.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkPublicKey.pb"

Procedure ChilkatExample()

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

    success.i

    ; Load our brainpool BP-256 public key.

    ; 	{
    ; 	  "use": "enc",
    ; 	  "kid": "puk_idp_enc",
    ; 	  "kty": "EC",
    ; 	  "crv": "BP-256",
    ; 	  "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w",
    ; 	  "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
    ; 	}

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

    CkJsonObject::ckUpdateString(json,"use","enc")
    CkJsonObject::ckUpdateString(json,"kid","puk_idp_enc")
    CkJsonObject::ckUpdateString(json,"kty","EC")
    CkJsonObject::ckUpdateString(json,"crv","BP-256")
    CkJsonObject::ckUpdateString(json,"x","QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w")
    CkJsonObject::ckUpdateString(json,"y","AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu")

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

    success = CkPublicKey::ckLoadFromString(pubkey,CkJsonObject::ckEmit(json))
    If success = 0
        Debug CkPublicKey::ckLastErrorText(pubkey)
        CkJsonObject::ckDispose(json)
        CkPublicKey::ckDispose(pubkey)
        ProcedureReturn
    EndIf

    ; Build our protected header:

    ; 	{
    ; 	  "alg": "ECDH-ES",
    ; 	  "enc": "A256GCM",
    ; 	  "exp": 1621957030,
    ; 	  "cty": "NJWT",
    ; 	  "epk": {
    ; 	    "kty": "EC",
    ; 	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
    ; 	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
    ; 	    "crv": "BP-256"
    ; 	  }
    ; 	}

    ; Use jwt only for getting the current date/time + 3600 seconds.
    jwt.i = CkJwt::ckCreate()
    If jwt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

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

    CkJsonObject::ckUpdateString(jweProtHdr,"alg","ECDH-ES")
    CkJsonObject::ckUpdateString(jweProtHdr,"enc","A256GCM")
    CkJsonObject::ckUpdateInt(jweProtHdr,"exp",CkJwt::ckGenNumericDate(jwt,3600))
    CkJsonObject::ckUpdateString(jweProtHdr,"cty","NJWT")
    CkJsonObject::ckUpdateString(jweProtHdr,"epk.kty","EC")
    CkJsonObject::ckUpdateString(jweProtHdr,"epk.x","QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w")
    CkJsonObject::ckUpdateString(jweProtHdr,"epk.y","AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu")
    CkJsonObject::ckUpdateString(jweProtHdr,"epk.crv","BP-256")

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

    CkJwe::ckSetProtectedHeader(jwe,jweProtHdr)
    CkJwe::ckSetPublicKey(jwe,0,pubkey)

    plainText.s = "This is the text to be encrypted."
    strJwe.s = CkJwe::ckEncrypt(jwe,plainText,"utf-8")
    If CkJwe::ckLastMethodSuccess(jwe) <> 1
        Debug CkJwe::ckLastErrorText(jwe)
        CkJsonObject::ckDispose(json)
        CkPublicKey::ckDispose(pubkey)
        CkJwt::ckDispose(jwt)
        CkJsonObject::ckDispose(jweProtHdr)
        CkJwe::ckDispose(jwe)
        ProcedureReturn
    EndIf

    Debug strJwe

    Debug "Success."


    CkJsonObject::ckDispose(json)
    CkPublicKey::ckDispose(pubkey)
    CkJwt::ckDispose(jwt)
    CkJsonObject::ckDispose(jweProtHdr)
    CkJwe::ckDispose(jwe)


    ProcedureReturn
EndProcedure