PureBasic

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. PureBasic

IncludeFile "CkBinData.pb"
IncludeFile "CkAsn.pb"
IncludeFile "CkHttp.pb"
IncludeFile "CkXml.pb"
IncludeFile "CkCrypt2.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkHttpResponse.pb"

Procedure ChilkatExample()

    success.i = 0

    ; 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.i = CkCrypt2::ckCreate()
    If crypt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkCrypt2::setCkHashAlgorithm(crypt, "sha256")
    CkCrypt2::setCkEncodingMode(crypt, "base64")
    base64Hash.s = CkCrypt2::ckHashFileENC(crypt,"qa_data/hamlet.xml")

    http.i = CkHttp::ckCreate()
    If http.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    requestToken.i = CkBinData::ckCreate()
    If requestToken.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    optionalPolicyOid.s = ""
    addNonce.i = 0
    requestTsaCert.i = 1

    ; Create a time-stamp request token
    success = CkHttp::ckCreateTimestampRequest(http,"sha256",base64Hash,optionalPolicyOid,addNonce,requestTsaCert,requestToken)
    If success = 0
        Debug CkHttp::ckLastErrorText(http)
        CkCrypt2::ckDispose(crypt)
        CkHttp::ckDispose(http)
        CkBinData::ckDispose(requestToken)
        ProcedureReturn
    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
    tsaUrl.s = "http://timestamp.digicert.com"
    resp.i = CkHttpResponse::ckCreate()
    If resp.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkHttp::ckHttpBd(http,"POST",tsaUrl,requestToken,"application/timestamp-query",resp)
    If success = 0
        Debug CkHttp::ckLastErrorText(http)
        CkCrypt2::ckDispose(crypt)
        CkHttp::ckDispose(http)
        CkBinData::ckDispose(requestToken)
        CkHttpResponse::ckDispose(resp)
        ProcedureReturn
    EndIf

    ; Get the timestamp reply from the HTTP response object.
    timestampReply.i = CkBinData::ckCreate()
    If timestampReply.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkHttpResponse::ckGetBodyBd(resp,timestampReply)

    ; Convert the binary timestamp reply to XML
    asn.i = CkAsn::ckCreate()
    If asn.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkAsn::ckLoadBd(asn,timestampReply)
    If success = 0
        Debug CkAsn::ckLastErrorText(asn)
        CkCrypt2::ckDispose(crypt)
        CkHttp::ckDispose(http)
        CkBinData::ckDispose(requestToken)
        CkHttpResponse::ckDispose(resp)
        CkBinData::ckDispose(timestampReply)
        CkAsn::ckDispose(asn)
        ProcedureReturn
    EndIf

    xml.i = CkXml::ckCreate()
    If xml.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkXml::ckLoadXml(xml,CkAsn::ckAsnToXml(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.s = CkXml::ckGetChildContent(xml,"sequence[1]|contextSpecific|sequence|sequence|contextSpecific|octets")

    bdTstInfo.i = CkBinData::ckCreate()
    If bdTstInfo.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkBinData::ckAppendEncoded(bdTstInfo,tstInfoBase64,"base64")

    asnTstInfo.i = CkAsn::ckCreate()
    If asnTstInfo.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkAsn::ckLoadBd(asnTstInfo,bdTstInfo)
    If success = 0
        Debug CkAsn::ckLastErrorText(asnTstInfo)
        CkCrypt2::ckDispose(crypt)
        CkHttp::ckDispose(http)
        CkBinData::ckDispose(requestToken)
        CkHttpResponse::ckDispose(resp)
        CkBinData::ckDispose(timestampReply)
        CkAsn::ckDispose(asn)
        CkXml::ckDispose(xml)
        CkBinData::ckDispose(bdTstInfo)
        CkAsn::ckDispose(asnTstInfo)
        ProcedureReturn
    EndIf

    xmlTstInfo.i = CkXml::ckCreate()
    If xmlTstInfo.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkXml::ckLoadXml(xmlTstInfo,CkAsn::ckAsnToXml(asnTstInfo))
    Debug CkXml::ckGetXml(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.i = CkStringBuilder::ckCreate()
    If sbGenTime.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckDecodeAndAppend(sbGenTime,CkXml::ckGetChildContent(xmlTstInfo,"universal"),"base64","utf-8")
    Debug CkStringBuilder::ckGetAsString(sbGenTime)

    ; Result:
    ; 20230316115718Z


    CkCrypt2::ckDispose(crypt)
    CkHttp::ckDispose(http)
    CkBinData::ckDispose(requestToken)
    CkHttpResponse::ckDispose(resp)
    CkBinData::ckDispose(timestampReply)
    CkAsn::ckDispose(asn)
    CkXml::ckDispose(xml)
    CkBinData::ckDispose(bdTstInfo)
    CkAsn::ckDispose(asnTstInfo)
    CkXml::ckDispose(xmlTstInfo)
    CkStringBuilder::ckDispose(sbGenTime)


    ProcedureReturn
EndProcedure