(Xojo Plugin) 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

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// 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"
Dim success As Boolean
Dim crypt As New Chilkat.Crypt2
crypt.HashAlgorithm = "sha256"
crypt.EncodingMode = "base64"
Dim base64Hash As String
base64Hash = crypt.HashFileENC("qa_data/hamlet.xml")

Dim http As New Chilkat.Http

Dim requestToken As New Chilkat.BinData
Dim optionalPolicyOid As String
optionalPolicyOid = ""
Dim addNonce As Boolean
addNonce = False
Dim requestTsaCert As Boolean
requestTsaCert = True

// Create a time-stamp request token
success = http.CreateTimestampRequest("sha256",base64Hash,optionalPolicyOid,addNonce,requestTsaCert,requestToken)
If (success = False) Then
    System.DebugLog(http.LastErrorText)
    Return
End If

// 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
Dim tsaUrl As String
tsaUrl = "http://timestamp.digicert.com"
Dim resp As Chilkat.HttpResponse
resp = http.PBinaryBd("POST",tsaUrl,requestToken,"application/timestamp-query",False,False)
If (http.LastMethodSuccess = False) Then
    System.DebugLog(http.LastErrorText)
    Return
End If

// Get the timestamp reply from the HTTP response object.
Dim timestampReply As New Chilkat.BinData
success = resp.GetBodyBd(timestampReply)

// Convert the binary timestamp reply to XML
Dim asn As New Chilkat.Asn
success = asn.LoadBd(timestampReply)
If (success = False) Then
    System.DebugLog(asn.LastErrorText)
    Return
End If

Dim xml As New Chilkat.Xml
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  }

Dim tstInfoBase64 As String
tstInfoBase64 = xml.GetChildContent("sequence[1]|contextSpecific|sequence|sequence|contextSpecific|octets")

Dim bdTstInfo As New Chilkat.BinData
success = bdTstInfo.AppendEncoded(tstInfoBase64,"base64")

Dim asnTstInfo As New Chilkat.Asn
success = asnTstInfo.LoadBd(bdTstInfo)
If (success = False) Then
    System.DebugLog(asnTstInfo.LastErrorText)
    Return
End If

Dim xmlTstInfo As New Chilkat.Xml
success = xmlTstInfo.LoadXml(asnTstInfo.AsnToXml())
System.DebugLog(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

Dim sbGenTime As New Chilkat.StringBuilder
success = sbGenTime.DecodeAndAppend(xmlTstInfo.GetChildContent("universal"),"base64","utf-8")
System.DebugLog(sbGenTime.GetAsString())

// Result:
// 20230316115718Z