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. Xojo Plugin

Dim success As Boolean
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"

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 New Chilkat.HttpResponse
success = http.HttpBd("POST",tsaUrl,requestToken,"application/timestamp-query",resp)
If (success = 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