Lianja Requires Chilkat v11.0.0+
Extract TSTInfo from RFC3161 Timestamp Reply

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.
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llSuccess = .F.

//  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"

loCrypt = createobject("CkCrypt2")
loCrypt.HashAlgorithm = "sha256"
loCrypt.EncodingMode = "base64"
lcBase64Hash = loCrypt.HashFileENC("qa_data/hamlet.xml")

loHttp = createobject("CkHttp")

loRequestToken = createobject("CkBinData")
lcOptionalPolicyOid = ""
llAddNonce = .F.
llRequestTsaCert = .T.

//  Create a time-stamp request token
llSuccess = loHttp.CreateTimestampRequest("sha256",lcBase64Hash,lcOptionalPolicyOid,llAddNonce,llRequestTsaCert,loRequestToken)
if (llSuccess = .F.) then
    ? loHttp.LastErrorText
    release loCrypt
    release loHttp
    release loRequestToken
    return
endif

//  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
lcTsaUrl = "http://timestamp.digicert.com"
loResp = createobject("CkHttpResponse")
llSuccess = loHttp.HttpBd("POST",lcTsaUrl,loRequestToken,"application/timestamp-query",loResp)
if (llSuccess = .F.) then
    ? loHttp.LastErrorText
    release loCrypt
    release loHttp
    release loRequestToken
    release loResp
    return
endif

//  Get the timestamp reply from the HTTP response object.
loTimestampReply = createobject("CkBinData")
loResp.GetBodyBd(loTimestampReply)

//  Convert the binary timestamp reply to XML
loAsn = createobject("CkAsn")
llSuccess = loAsn.LoadBd(loTimestampReply)
if (llSuccess = .F.) then
    ? loAsn.LastErrorText
    release loCrypt
    release loHttp
    release loRequestToken
    release loResp
    release loTimestampReply
    release loAsn
    return
endif

loXml = createobject("CkXml")
llSuccess = loXml.LoadXml(loAsn.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  }

lcTstInfoBase64 = loXml.GetChildContent("sequence[1]|contextSpecific|sequence|sequence|contextSpecific|octets")

loBdTstInfo = createobject("CkBinData")
loBdTstInfo.AppendEncoded(lcTstInfoBase64,"base64")

loAsnTstInfo = createobject("CkAsn")
llSuccess = loAsnTstInfo.LoadBd(loBdTstInfo)
if (llSuccess = .F.) then
    ? loAsnTstInfo.LastErrorText
    release loCrypt
    release loHttp
    release loRequestToken
    release loResp
    release loTimestampReply
    release loAsn
    release loXml
    release loBdTstInfo
    release loAsnTstInfo
    return
endif

loXmlTstInfo = createobject("CkXml")
llSuccess = loXmlTstInfo.LoadXml(loAsnTstInfo.AsnToXml())
? loXmlTstInfo.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

loSbGenTime = createobject("CkStringBuilder")
loSbGenTime.DecodeAndAppend(loXmlTstInfo.GetChildContent("universal"),"base64","utf-8")
? loSbGenTime.GetAsString()

//  Result:
//  20230316115718Z


release loCrypt
release loHttp
release loRequestToken
release loResp
release loTimestampReply
release loAsn
release loXml
release loBdTstInfo
release loAsnTstInfo
release loXmlTstInfo
release loSbGenTime