Java Requires Chilkat v11.0.0+

Extract TSTInfo from RFC3161 Timestamp Reply

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Sends an RFC 3161 timestamp request to a TSA (Timestamp Authority) server and converts the timestamp reply to XML, and then extracts the TSTInfo from the XML and converts it to XML. Chilkat2 Java

import com.chilkatsoft.chilkat2.Asn;
import com.chilkatsoft.chilkat2.BinData;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Crypt2;
import com.chilkatsoft.chilkat2.Http;
import com.chilkatsoft.chilkat2.HttpResponse;
import com.chilkatsoft.chilkat2.StringBuilder;
import com.chilkatsoft.chilkat2.Xml;

public class ChilkatExample {

    public static void main(String[] args) {
        // Note: Requires Chilkat v9.5.0.75 or greater.

        // This requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        // First sha-256 hash the data that is to be timestamped.
        // In this example, the data is the string "Hello World"

        Crypt2 crypt = new Crypt2();
        crypt.setHashAlgorithm("sha256");
        crypt.setEncodingMode("base64");
        String base64Hash = crypt.hashFileENC("qa_data/hamlet.xml");

        Http http = new Http();

        BinData requestToken = new BinData();
        String optionalPolicyOid = "";
        boolean addNonce = false;
        boolean requestTsaCert = true;

        // Create a time-stamp request token
        try {
            http.createTimestampRequest("sha256", base64Hash, optionalPolicyOid, addNonce, requestTsaCert, requestToken);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Send the time-stamp request token to the TSA.
        // This is the equivalent of the following CURL command:
        // curl -H "Content-Type: application/timestamp-query" --data-binary '@file.tsq' http://timestamp.digicert.com > file.tsr
        String tsaUrl = "http://timestamp.digicert.com";
        HttpResponse resp = new HttpResponse();
        try {
            http.httpBd("POST", tsaUrl, requestToken, "application/timestamp-query", resp);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Get the timestamp reply from the HTTP response object.
        BinData timestampReply = new BinData();
        resp.getBodyBd(timestampReply);

        // Convert the binary timestamp reply to XML
        Asn asn = new Asn();
        try {
            asn.loadBd(timestampReply);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        Xml xml = new Xml();
        xml.loadXml(asn.asnToXml());

        // Extract the TSTInfo from the XML.
        // The TSTInfo is this base64 encoded ASN.1

        // TSTInfo ::= SEQUENCE  {
        //    version                      INTEGER  { v1(1) },
        //    policy                       TSAPolicyId,
        //    messageImprint               MessageImprint,
        //      -- MUST have the same value as the similar field in
        //      -- TimeStampReq
        //    serialNumber                 INTEGER,
        //     -- Time-Stamping users MUST be ready to accommodate integers
        //     -- up to 160 bits.
        //    genTime                      GeneralizedTime,
        //    accuracy                     Accuracy                 OPTIONAL,
        //    ordering                     BOOLEAN             DEFAULT FALSE,
        //    nonce                        INTEGER                  OPTIONAL,
        //      -- MUST be present if the similar field was present
        //      -- in TimeStampReq.  In that case it MUST have the same value.
        //    tsa                          [0] GeneralName          OPTIONAL,
        //    extensions                   [1] IMPLICIT Extensions   OPTIONAL  }

        String tstInfoBase64 = xml.getChildContent("sequence[1]|contextSpecific|sequence|sequence|contextSpecific|octets");

        BinData bdTstInfo = new BinData();
        bdTstInfo.appendEncoded(tstInfoBase64, "base64");

        Asn asnTstInfo = new Asn();
        try {
            asnTstInfo.loadBd(bdTstInfo);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        Xml xmlTstInfo = new Xml();
        xmlTstInfo.loadXml(asnTstInfo.asnToXml());
        System.out.println(xmlTstInfo.getXml());

        // Here's the TSTInfo XML:

        // <?xml version="1.0" encoding="utf-8"?>
        // <sequence>
        //     <int>01</int>
        //     <oid>2.16.840.1.114412.7.1</oid>
        //     <sequence>
        //         <sequence>
        //             <oid>2.16.840.1.101.3.4.2.1</oid>
        //             <null/>
        //         </sequence>
        //         <octets>4sRRyWOzC7EOic4fQ9+Op1pa10DbgoBGjBvkq09LZmE=</octets>
        //     </sequence>
        //     <int>00AD2C86E49872597B60F87D5C54BCFFAE</int>
        //     <universal tag="24" constructed="0">MjAyMzAzMTYxMTQ5NTJa</universal>
        // </sequence>

        //    The genTime (GeneralizedTime) is contained in the final "universal" XML element and is
        //    in base64. It is the time at which the time-stamp token has been created by
        //    the TSA. After decoding from base64, it is:
        //
        //    The syntax is: YYYYMMDDhhmmss[.s...]Z
        //    Example: 19990609001326.34352Z

        StringBuilder sbGenTime = new StringBuilder();
        sbGenTime.decodeAndAppend(xmlTstInfo.getChildContent("universal"), "base64", "utf-8");
        System.out.println(sbGenTime.getAsString());

        // Result:
        // 20230316115718Z
    }
}