Scala compilation issue when using Java library with interface using generic type

Question

In a Scala project, I am using Java livrary (bouncycastle).

I have a compilation issue when using a method that required an object implementing a generic type.

Here is the interface in Java:

public interface Selector<T> extends Cloneable
{
    boolean match(T obj);
    Object clone();
}

Here is the piece of code that does not compile:

def verify(data: File): Boolean = {
    val signedData = new CMSSignedData(new CMSProcessableFile(data), Base64.decode(this.value))
    val certStore = signedData.getCertificates
    val signers = signedData.getSignerInfos.getSigners
    val signer = signers.iterator.next
    val certs = certStore.getMatches(signer.getSID)
    val cert = certs.iterator.next.asInstanceOf[X509CertificateHolder]
    signer.verify(new JcaSimpleSignerInfoVerifierBuilder().setProvider("BC").build(cert))
}

When I compile the code, I get the following error:

[error]  found   : org.bouncycastle.cms.SignerId
[error]  required: org.bouncycastle.util.Selector[?0]
[error]     val certs = certStore.getMatches(signer.getSID)

I tried casting but I does not compile.

Coule you please help?

Regards,

What is the signature of getMatches ?

pedrofurla
– pedrofurla

2016-08-06 10:56:22 +00:00
Commented Aug 6, 2016 at 10:56 — pedrofurla
– pedrofurla, Commented Aug 6, 2016 at 10:56

Alexey Romanov · Accepted Answer · 2016-08-06 12:34:07Z

1

If you look at https://www.bouncycastle.org/docs/pkixdocs1.5on/org/bouncycastle/cms/CMSSignedData.html, getCertificates returns a raw Store object instead of Store<Something>. Scala doesn't support working with raw types, generally speaking (they only exist in Java to interoperate with pre-Java-5 code). It's documented as

Return any X.509 certificate objects in this SignedData structure as a Store of X509CertificateHolder objects.

So you can try

val certStore = signedData.getCertificates.asInstanceOf[Store[X509CertificateHolder]]

and you'll also need casts in any other places where raw Store or Selector are returned.

edited Aug 6, 2016 at 12:34

answered Aug 6, 2016 at 12:27

Alexey Romanov

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Jean-Julien Alvado · Accepted Answer · 2016-08-07 13:47:51Z

0

Here is what I modified:

def verify(data: File): Boolean = {
  val signedData = new CMSSignedData(new CMSProcessableFile(data), Base64.decode(this.value))
  val certStore = signedData.getCertificates.asInstanceOf[Store[X509CertificateHolder]]
  val signers = signedData.getSignerInfos.getSigners
  val signer = signers.iterator.next
  val certs = certStore.getMatches(signer.getSID.asInstanceOf[Selector[X509CertificateHolder]])
  val cert = certs.iterator.next
  signer.verify(new JcaSimpleSignerInfoVerifierBuilder().setProvider("BC").build(cert))
}

Now, the code compile without problem!

Thanks a lot.

Kind Regards,

answered Aug 7, 2016 at 13:47

Jean-Julien Alvado

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