DebugDigestCalculatorProvider.java

import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.operator.DigestCalculator;
import org.bouncycastle.operator.DigestCalculatorProvider;
import org.bouncycastle.operator.OperatorCreationException;
import org.bouncycastle.operator.bc.BcDefaultDigestProvider;
import org.bouncycastle.operator.bc.BcDigestProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;

public class DebugDigestCalculatorProvider implements DigestCalculatorProvider {
    private final BcDigestProvider digestProvider = BcDefaultDigestProvider.INSTANCE;
    private static final Logger LOGGER = LoggerFactory.getLogger(DebugDigestCalculatorProvider.class);

    public DigestCalculator get(final AlgorithmIdentifier algorithm) throws OperatorCreationException {
        Digest dig = digestProvider.get(algorithm);

        final DigestOutputStream stream = new DigestOutputStream(dig);

        return new DigestCalculator() {
            @Override
            public AlgorithmIdentifier getAlgorithmIdentifier() {
                return algorithm;
            }

            @Override
            public OutputStream getOutputStream() {
                return stream;
            }

            @Override
            public byte[] getDigest() {
                return stream.getDigest();
            }
        };
    }

    private static class DigestOutputStream extends OutputStream {
        private final Digest dig;

        DigestOutputStream(Digest dig) {
            LOGGER.info("DigestOutputStream, digest = " + dig.getAlgorithmName());
            this.dig = dig;
        }

        public void write(byte[] bytes, int off, int len) throws IOException {
            System.out.print(new String(bytes, off, len, StandardCharsets.ISO_8859_1).replace("\t", "[TAB]").replace("\r", "[CR]").replace("\n", "[LF]"));
            dig.update(bytes, off, len);
        }

        public void write(byte[] bytes) throws IOException {
            System.out.print(new String(bytes, StandardCharsets.ISO_8859_1).replace("\t", "[TAB]").replace("\r", "[CR]").replace("\n", "[LF]"));
            dig.update(bytes, 0, bytes.length);
        }

        public void write(int b) throws IOException {
            System.out.print(new String(new byte[] { (byte) b }, StandardCharsets.ISO_8859_1).replace("\t", "[TAB]").replace("\r", "[CR]").replace("\n", "[LF]"));
            dig.update((byte) b);
        }

        byte[] getDigest() {
            byte[] d = new byte[dig.getDigestSize()];

            dig.doFinal(d, 0);

            LOGGER.info("Digest: " + CertificateUtils.bytesToHex(d));
            return d;
        }
    }
}