convert

import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.openssl.PEMException;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.PrivateKey;
import java.util.ArrayList;
import java.util.List;

public class A {
    public static PrivateKeyInfo[] getPrivateKeyInfo(InputStream inputStream) throws IOException  {
        PEMParser pemRd = new PEMParser(new InputStreamReader(inputStream));
        List<PrivateKeyInfo> list = new ArrayList<>();
        while (true) {
            Object object = pemRd.readObject();
            if (object == null) {
                break;
            }
            if (object instanceof PEMKeyPair) {
                list.add(((PEMKeyPair)object).getPrivateKeyInfo());
            } else if (object instanceof PrivateKeyInfo) {
                list.add((PrivateKeyInfo)object);
            }
        }
        return list.toArray(new PrivateKeyInfo[list.size()]);
    }

    public static PrivateKey[] getPrivateKey(PrivateKeyInfo[] info) throws PEMException {
        List<PrivateKey> list = new ArrayList<>();
        for (int i = 0; i < info.length; i++) {
            PrivateKey pair = new JcaPEMKeyConverter().getPrivateKey(info[i]);
            list.add(pair);
        }
        return list.toArray(new PrivateKey[list.size()]);
    }
}