(PHP Extension) 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.

For more information, see https://www.ietf.org/rfc/rfc3161.txt

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// 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 = new CkCrypt2();
$crypt->put_HashAlgorithm('sha256');
$crypt->put_EncodingMode('base64');
$base64Hash = $crypt->hashFileENC('qa_data/hamlet.xml');

$http = new CkHttp();

$requestToken = new CkBinData();
$optionalPolicyOid = '';
$addNonce = false;
$requestTsaCert = true;

// Create a time-stamp request token
$success = $http->CreateTimestampRequest('sha256',$base64Hash,$optionalPolicyOid,$addNonce,$requestTsaCert,$requestToken);
if ($success == false) {
    print $http->lastErrorText() . "\n";
    exit;
}

// 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 is a CkHttpResponse
$resp = $http->PBinaryBd('POST',$tsaUrl,$requestToken,'application/timestamp-query',false,false);
if ($http->get_LastMethodSuccess() == false) {
    print $http->lastErrorText() . "\n";
    exit;
}

// Get the timestamp reply from the HTTP response object.
$timestampReply = new CkBinData();
$resp->GetBodyBd($timestampReply);

// Convert the binary timestamp reply to XML
$asn = new CkAsn();
$success = $asn->LoadBd($timestampReply);
if ($success == false) {
    print $asn->lastErrorText() . "\n";
    exit;
}

$xml = new CkXml();
$success = $xml->LoadXml($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  }

$tstInfoBase64 = $xml->getChildContent('sequence[1]|contextSpecific|sequence|sequence|contextSpecific|octets');

$bdTstInfo = new CkBinData();
$bdTstInfo->AppendEncoded($tstInfoBase64,'base64');

$asnTstInfo = new CkAsn();
$success = $asnTstInfo->LoadBd($bdTstInfo);
if ($success == false) {
    print $asnTstInfo->lastErrorText() . "\n";
    exit;
}

$xmlTstInfo = new CkXml();
$success = $xmlTstInfo->LoadXml($asnTstInfo->asnToXml());
print $xmlTstInfo->getXml() . "\n";

// 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 = new CkStringBuilder();
$sbGenTime->DecodeAndAppend($xmlTstInfo->getChildContent('universal'),'base64','utf-8');
print $sbGenTime->getAsString() . "\n";

// Result:
// 20230316115718Z

?>