从服务请求时间戳

Question

我创建了一个示例项目，说明如何直接在Android上向时间戳提供者授权机构（在本示例中为freetsa）请求时间戳记文档。我做了研究，最接近的是使用BouncyCastle Java实现（链接到代码示例）。但这是行不通的。根据freetsa docs，我应该生成一个tsq文件并收到一个tsr。但是BouncyCastle使用对象TimeStampReq和TimeStampResponse。那些相等吗？有什么可以借鉴的例子吗？项目为here，相关代码如下。

private void createHash2() throws NoSuchAlgorithmException, IOException, TSPException {
    // https:stackoverflow.com/questions/28085619/timestamping-using-tsa-url-and-java-apis

    // for this sample we will use SHA1 to perform the hashes
    // however feel free to use another algorithm since sha1 is weakness
    String sha1Oid = "1.3.14.3.2.26";
    // data to be timestamped
    byte[] data = "some sample data... or your signature...".getBytes();

    // perform the hash of your data
    byte[] digestData = MessageDigest.getInstance(sha1Oid, new BouncyCastleProvider()).digest(data);
    // generate random data to perform your ts, it's optional depends on your ts service
    Random rand = new Random(new Date().getTime());
    String nonce = BigInteger.valueOf(rand.nextLong()).toString();
    // require cert optional (default false... so use false)
    boolean requireCert = false;
    // timestampPolicy it's an oid to identify a policy, if it's required
    // must be provided by your ts service... it's optional so we put null
    String timestampPolicy = null;

    TimeStampReq ts_req = createTimeStampRequest(digestData, nonce, requireCert, sha1Oid, timestampPolicy);

    // the data to be send to the service
    try {
        byte[] dataToSend = ts_req.getEncoded();
    }
    catch (IOException e) {
        e.printStackTrace();
    }

    // simply send your data using POST method
    // don't forget to specify http-header content-type as "application/timestamp-query"
    byte[] response = makeHttpRequest();// send the request as you want
    // parse the response
    ASN1StreamParser asn1Sp = new ASN1StreamParser(response);
    TimeStampResp tspResp = null;
    try {
        tspResp = TimeStampResp.getInstance((ASN1Sequence) asn1Sp.readObject());// new TimeStampResp((ASN1Sequence)asn1Sp.readObject());
    }
    catch (IOException e) {
        e.printStackTrace();
    }
    TimeStampResponse tsr = new TimeStampResponse(tspResp);
    // and get the timestamp token :)
    TimeStampToken token = tsr.getTimeStampToken();
}

private byte[] makeHttpRequest() {

    InputStream input = null;
    OutputStream output = null;
    HttpURLConnection connection = null;
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

    byte[] result;

    try {
        URL url = new URL("https://freetsa.org/tsr");
        connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "application/timestamp-query");
        connection.connect();

        if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
            Log.i(TAG, "Server returned HTTP " + connection.getResponseCode()
                       + " " + connection.getResponseMessage());
            return new byte[0];
        }

        File file = getExternalStorageDir("pdffile.tsr");

        // download the file
        input = connection.getInputStream();
        output = new FileOutputStream(file);

        long total = 0;
        int count;
        byte data[] = new byte[4096];
        while ((count = input.read(data)) != -1) {
            total += count;
            output.write(data, 0, count);
            byteArrayOutputStream.write(data, 0, count);
        }
    }
    catch (IOException e) {
        e.printStackTrace();
    }
    finally {
        try {
            if (output != null) {
                output.close();
            }
            if (input != null) {
                input.close();
            }
            if (byteArrayOutputStream != null) {
                result = byteArrayOutputStream.toByteArray();
                byteArrayOutputStream.close();
                return result;
            }
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        if (connection != null) {
            connection.disconnect();
        }
    }

    return new byte[0];
}

public static TimeStampReq createTimeStampRequest(byte[] hashedData, String nonce, boolean requireCert, String digestAlgorithm, String timestampPolicy) {

    MessageImprint imprint = new MessageImprint(new AlgorithmIdentifier(new ASN1ObjectIdentifier(digestAlgorithm)), hashedData);

    TimeStampReq request = new TimeStampReq(
            imprint,
            timestampPolicy!=null ? new DERObjectIdentifier(timestampPolicy) : null,
            nonce!=null ? new DERInteger(nonce.getBytes()) : null,
            new DERBoolean(requireCert),
            null
    );

    return request;
}

private File getExternalStorageDir(String fileName) {
    // Get the directory for the user's public pictures directory.
    File downloadDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
    downloadDirectory.mkdirs();
    return new File(downloadDirectory, fileName);
}