PureBasic Requires Chilkat v11.0.0+

Validate JWS Using HMAC SHA-256

See more JSON Web Signatures (JWS) Examples

Validates a JSON Web Signature (JWS) using HMAC SHA-256. PureBasic

IncludeFile "CkJws.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    success.i = 0

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

    ;  This example takes a JSON signature in compact serialization format,
    ;  and uses a MAC key to validate and recover the protected header and payload.

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

    ;  Set the HMAC key:
    hmacKey.s = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
    signatureIndex.i = 0
    CkJws::ckSetMacKey(jws,signatureIndex,hmacKey,"base64url")

    ;  Load the JWS.
    jwsCompact.s = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"
    success = CkJws::ckLoadJws(jws,jwsCompact)

    ;  Validate the 1st (and only) signature at index 0..
    v.i = CkJws::ckValidate(jws,signatureIndex)
    If v < 0
        ;  Perhaps Chilkat was not unlocked or the trial expired..
        Debug "Method call failed for some other reason."
        Debug CkJws::ckLastErrorText(jws)
        CkJws::ckDispose(jws)
        ProcedureReturn
    EndIf

    If v = 0
        Debug "Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both."
        CkJws::ckDispose(jws)
        ProcedureReturn
    EndIf

    ;  If we get here, the signature was validated..
    Debug "Signature validated."

    ;  Recover the original content:
    Debug "Recovered content:"
    Debug CkJws::ckGetPayload(jws,"utf-8")

    ;  Examine the protected header:

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

    success = CkJws::ckGetProtectedH(jws,signatureIndex,joseHeader)
    If success = 0
        Debug CkJws::ckLastErrorText(jws)
        CkJws::ckDispose(jws)
        CkJsonObject::ckDispose(joseHeader)
        ProcedureReturn
    EndIf

    CkJsonObject::setCkEmitCompact(joseHeader, 0)

    Debug "Protected (JOSE) header:"
    Debug CkJsonObject::ckEmit(joseHeader)

    ;  Output:

    ;  	Signature validated.
    ;  	Recovered content:
    ;  	{"iss":"joe",
    ;  	 "exp":1300819380,
    ;  	 "http://example.com/is_root":true}
    ;  	Protected (JOSE) header:
    ;  	{ 
    ;  	  "typ": "JWT",
    ;  	  "alg": "HS256"
    ;  	}


    CkJws::ckDispose(jws)
    CkJsonObject::ckDispose(joseHeader)


    ProcedureReturn
EndProcedure