(DataFlex) Validate a JWS Using ECDSA P-256 SHA-256

Validates a JSON Web Signature (JWS) that uses ECDSA P-256 SHA-256

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

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoSbPubKey
    Boolean iSuccess
    Variant vPubKey
    Handle hoPubKey
    Boolean iSuccess
    Handle hoJws
    Integer iSignatureIndex
    Variant vSbJws
    Handle hoSbJws
    Integer v
    Variant vJoseHeader
    Handle hoJoseHeader
    String sTemp1
    Boolean bTemp1

    // 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.

    // This example takes a JSON signature in compact serialization format,
    // and uses an ECDSA public key to validate and recover the protected header and payload.

    // We only need a public key for signature validation.  This is the ECDSA public key
    // that is used:

    //      {"kty":"EC", 
    //       "crv":"P-256", 
    //       "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU", 
    //       "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0" 
    //      } 

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbPubKey
    If (Not(IsComObjectCreated(hoSbPubKey))) Begin
        Send CreateComObject of hoSbPubKey
    End
    Get ComAppend Of hoSbPubKey '{"kty":"EC",' To iSuccess
    Get ComAppend Of hoSbPubKey '"crv":"P-256",' To iSuccess
    Get ComAppend Of hoSbPubKey '"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",' To iSuccess
    Get ComAppend Of hoSbPubKey '"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"' To iSuccess
    Get ComAppend Of hoSbPubKey "}" To iSuccess

    Get Create (RefClass(cComChilkatPublicKey)) To hoPubKey
    If (Not(IsComObjectCreated(hoPubKey))) Begin
        Send CreateComObject of hoPubKey
    End
    Get ComGetAsString Of hoSbPubKey To sTemp1
    Get ComLoadFromString Of hoPubKey sTemp1 To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoPubKey To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatJws)) To hoJws
    If (Not(IsComObjectCreated(hoJws))) Begin
        Send CreateComObject of hoJws
    End

    // Set the ECC public key:
    Move 0 To iSignatureIndex
    Get pvComObject of hoPubKey to vPubKey
    Get ComSetPublicKey Of hoJws iSignatureIndex vPubKey To iSuccess

    // Load the JWS.
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbJws
    If (Not(IsComObjectCreated(hoSbJws))) Begin
        Send CreateComObject of hoSbJws
    End
    Get ComAppend Of hoSbJws "eyJhbGciOiJFUzI1NiJ9" To iSuccess
    Get ComAppend Of hoSbJws "." To iSuccess
    Get ComAppend Of hoSbJws "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt" To iSuccess
    Get ComAppend Of hoSbJws "cGxlLmNvbS9pc19yb290Ijp0cnVlfQ" To iSuccess
    Get ComAppend Of hoSbJws "." To iSuccess
    Get ComAppend Of hoSbJws "DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA" To iSuccess
    Get ComAppend Of hoSbJws "pmWQxfKTUJqPP3-Kg6NU1Q" To iSuccess

    Get pvComObject of hoSbJws to vSbJws
    Get ComLoadJwsSb Of hoJws vSbJws To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoJws To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Validate the 1st (and only) signature at index 0..
    Get ComValidate Of hoJws iSignatureIndex To v
    If (v < 0) Begin
        // Perhaps Chilkat was not unlocked or the trial expired..
        Showln "Method call failed for some other reason."
        Get ComLastErrorText Of hoJws To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    If (v = 0) Begin
        Showln "Invalid signature.  The ECC key was incorrect, the JWS was invalid, or both."
        Procedure_Return
    End

    // If we get here, the signature was validated..
    Showln "Signature validated."
    Showln "--"

    // Recover the original content:
    Showln "Recovered content:"
    Get ComGetPayload Of hoJws "utf-8" To sTemp1
    Showln sTemp1
    Showln "--"

    // Examine the protected header:
    Get ComGetProtectedHeader Of hoJws iSignatureIndex To vJoseHeader
    If (IsComObject(vJoseHeader)) Begin
        Get Create (RefClass(cComChilkatJsonObject)) To hoJoseHeader
        Set pvComObject Of hoJoseHeader To vJoseHeader
    End
    Get ComLastMethodSuccess Of hoJws To bTemp1
    If (bTemp1 <> True) Begin
        Showln "No protected header found at the given index."
        Procedure_Return
    End

    Set ComEmitCompact Of hoJoseHeader To False

    Showln "Protected (JOSE) header:"
    Get ComEmit Of hoJoseHeader To sTemp1
    Showln sTemp1
    Send Destroy of hoJoseHeader

    // Output:

    // 	Signature validated.
    // 	--
    // 	Recovered content:
    // 	{"iss":"joe",
    // 	 "exp":1300819380,
    // 	 "http://example.com/is_root":true}
    // 	--
    // 	Protected (JOSE) header:
    // 	{ 
    // 	  "alg": "ES256"
    // 	}


End_Procedure