Delphi DLL

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. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Asn, HttpResponse, Http, BinData, StringBuilder, Xml, Crypt2;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
crypt: HCkCrypt2;
base64Hash: PWideChar;
http: HCkHttp;
requestToken: HCkBinData;
optionalPolicyOid: PWideChar;
addNonce: Boolean;
requestTsaCert: Boolean;
tsaUrl: PWideChar;
resp: HCkHttpResponse;
timestampReply: HCkBinData;
asn: HCkAsn;
xml: HCkXml;
tstInfoBase64: PWideChar;
bdTstInfo: HCkBinData;
asnTstInfo: HCkAsn;
xmlTstInfo: HCkXml;
sbGenTime: HCkStringBuilder;

begin
success := False;

// 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"

crypt := CkCrypt2_Create();
CkCrypt2_putHashAlgorithm(crypt,'sha256');
CkCrypt2_putEncodingMode(crypt,'base64');
base64Hash := CkCrypt2__hashFileENC(crypt,'qa_data/hamlet.xml');

http := CkHttp_Create();

requestToken := CkBinData_Create();
optionalPolicyOid := '';
addNonce := False;
requestTsaCert := True;

// Create a time-stamp request token
success := CkHttp_CreateTimestampRequest(http,'sha256',base64Hash,optionalPolicyOid,addNonce,requestTsaCert,requestToken);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

// 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
tsaUrl := 'http://timestamp.digicert.com';
resp := CkHttpResponse_Create();
success := CkHttp_HttpBd(http,'POST',tsaUrl,requestToken,'application/timestamp-query',resp);
if (success = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

// Get the timestamp reply from the HTTP response object.
timestampReply := CkBinData_Create();
CkHttpResponse_GetBodyBd(resp,timestampReply);

// Convert the binary timestamp reply to XML
asn := CkAsn_Create();
success := CkAsn_LoadBd(asn,timestampReply);
if (success = False) then
  begin
    Memo1.Lines.Add(CkAsn__lastErrorText(asn));
    Exit;
  end;

xml := CkXml_Create();
success := CkXml_LoadXml(xml,CkAsn__asnToXml(asn));

// 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  }

tstInfoBase64 := CkXml__getChildContent(xml,'sequence[1]|contextSpecific|sequence|sequence|contextSpecific|octets');

bdTstInfo := CkBinData_Create();
CkBinData_AppendEncoded(bdTstInfo,tstInfoBase64,'base64');

asnTstInfo := CkAsn_Create();
success := CkAsn_LoadBd(asnTstInfo,bdTstInfo);
if (success = False) then
  begin
    Memo1.Lines.Add(CkAsn__lastErrorText(asnTstInfo));
    Exit;
  end;

xmlTstInfo := CkXml_Create();
success := CkXml_LoadXml(xmlTstInfo,CkAsn__asnToXml(asnTstInfo));
Memo1.Lines.Add(CkXml__getXml(xmlTstInfo));

// 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

sbGenTime := CkStringBuilder_Create();
CkStringBuilder_DecodeAndAppend(sbGenTime,CkXml__getChildContent(xmlTstInfo,'universal'),'base64','utf-8');
Memo1.Lines.Add(CkStringBuilder__getAsString(sbGenTime));

// Result:
// 20230316115718Z

CkCrypt2_Dispose(crypt);
CkHttp_Dispose(http);
CkBinData_Dispose(requestToken);
CkHttpResponse_Dispose(resp);
CkBinData_Dispose(timestampReply);
CkAsn_Dispose(asn);
CkXml_Dispose(xml);
CkBinData_Dispose(bdTstInfo);
CkAsn_Dispose(asnTstInfo);
CkXml_Dispose(xmlTstInfo);
CkStringBuilder_Dispose(sbGenTime);

end;