How to create CMSSignedData instance that accepts webcrypto ECDSA signatures

[CipherTrustee]

I need help adapting the Groovy code below to work with ECDSA signature generated via webcrypto. The signature is in the r|s form. I have incorporated the toASN1 converter as implemented here: https://gist.github.com/DinoChiesa/7520e1dea6e79888acab8ea8206afe92

It results in malformed content error owing apparently to expecting the first entry in the toASN1 sequence to be an OID.

    public boolean verify(String signedString,String signature,Object signerCert)
    {
        //Create a CMSProcessable object, specify any encoding 
        CMSProcessable signedContent = new CMSProcessableByteArray(DigestUtils.sha256Hex(signedString).getBytes());
        //Create a InputStream object
        InputStream is = new ByteArrayInputStream(toASN1(Base64.decodeBase64(signature.getBytes())));
        //Pass them both to CMSSignedData constructor
        CMSSignedData signedData = new CMSSignedData(signedContent, is);     
      
        Store store = signedData.getCertificates();

        if(signerCert != null){
            //Build CMS
            List certList = new ArrayList();
            certList.add(signerCert);
            store =  new JcaCertStore(certList);
        } 


        SignerInformationStore signers = signedData.getSignerInfos(); 

        Collection c = signers.getSigners(); 
        Iterator it = c.iterator(); 

        while (it.hasNext()) { 
            SignerInformation signer = (SignerInformation)it.next(); 

            Collection certCollection = store.getMatches(signer.getSID()); 
            Iterator certIt = certCollection.iterator(); 

            X509CertificateHolder certHolder = (X509CertificateHolder)certIt.next(); 
            X509Certificate cert = new JcaX509CertificateConverter().setProvider("BC").getCertificate(certHolder); 

            if (signer.verify(new JcaSimpleSignerInfoVerifierBuilder().setProvider("BC").build(cert))) {
              return true; 
            }
        }
        return false;
    }