public ExaminationStudentsFilter(FilterationSecurityLevel securityLevel, string examKey, string instPassword, SortedList <string, ExaminationFilterRule> rules = null)
{
SecurityLevel = securityLevel;
ExamKey = examKey;
InstructorPassword = instPassword;
Rules = rules;
}
public static bool ValidateExamCopy(string examCopy, string studentPassword, Logger aLogger, string sharedKeyIS, FilterationSecurityLevel secLevel, string SequenceNumberOriginal)
{
try
{
var x = GetExamFromByteArray(examCopy, studentPassword, sharedKeyIS, secLevel);
long orgSN = long.Parse(SequenceNumberOriginal);
long newSN = long.Parse(x.RequiredStudentDetails.SequenceNumber);
if (orgSN == newSN - 1)
{
aLogger.LogMessage("[Correct Sequence Number ::: Exam Validated Correctly]", LogMsgType.Verbose);
return(true);
}
else
{
aLogger.LogMessage($"[Incorrect Sequence Number ::: Wrong Exam ... OriginalSN:[{SequenceNumberOriginal}], ReceivedSN:[{x.RequiredStudentDetails.SequenceNumber}]", LogMsgType.Verbose);
return(false);
}
}
catch (Exception ex)
{
aLogger.LogMessage("INVALID EXAM FILE OR PASSWORD:" + ex.ToString(), LogMsgType.Error);
return(false);
}
}
private SortedList <int, ExaminationStudentsFilter> GetFirewalls(int numberofStdsInit, int MaxStdNum,
string studentPassword, string instructorPassword, int step, FilterationSecurityLevel secLevel)
{
SortedList <int, ExaminationStudentsFilter> ret = new SortedList <int, ExaminationStudentsFilter>();
Parallel.ForEach(BetterEnumerable.SteppedRange(numberofStdsInit, MaxStdNum, step), (index) =>
{
SortedList <string, ExaminationFilterRule> rules = new SortedList <string, ExaminationFilterRule>();
for (int i = 0; i < index; i++)
{
rules.Add($"Std{i}", new ExaminationFilterRule
{
StdID = $"Std{i}",
StdName = $"StdName{i}",
AllowSpecificIPs = false,
AllowedIPs = new List <string>
{
"ANY",
},
SharedKeyIS = $"Keyyyyyyy{i}",
});
}
lock (ret)
{
ret.Add(index, new ExaminationStudentsFilter(secLevel,
studentPassword, instructorPassword, rules));
}
});
return(ret);
}
public static Exam GetExamFromByteArray(string encryptedFile, string examKey, string sharedKeyIS, FilterationSecurityLevel secLevel)
{
string decrypted;
if (secLevel == FilterationSecurityLevel.Moderate)
{
decrypted = AESGCM.SimpleDecryptWithPassword(encryptedFile, examKey);
}
else
{
decrypted = AESGCM.SimpleDecryptWithPassword(encryptedFile, sharedKeyIS);
}
//unzip
if (decrypted == null)
{
int x = 10;
}
var unzippedFile = Framework_Project.Compression.CompressionHelper.Unzip(decrypted);
if (unzippedFile.Substring(0, 3) != "FCT")
{
throw new InvalidStudentPasswordException("In GetExamFromFile");
}
unzippedFile = unzippedFile.Substring(3, unzippedFile.Length - 3);
try
{
var exmp = Framework_Project.Serialization.SerializationHelper.Deserialize <Exam>(unzippedFile);
return(exmp);
}
catch (Exception ex)
{
throw new Exception("in GetExamFromFile, cannot cast the XML to Exam Class. ");
}
}
public static Exam GetExamFromString(string zippedFile, string studentPassword, string sharedKeyIS, FilterationSecurityLevel secLevel)
{
//string byteArray = "";
// int indexBA = 0;
// foreach (char item in zippedFile.ToCharArray())
// {
// byteArray[indexBA++] = (byte)item;
// }
return(GetExamFromByteArray(zippedFile, studentPassword, sharedKeyIS, secLevel));
}
public static Exam GetExamFromFile(string fileLocation, string studentPassword, string sharedKeyIS, FilterationSecurityLevel secLevel)
{
//Get byte array from file name
//var encrypted = GetExamFileAsBytes(fileLocation);
var encrypted = File.ReadAllText(fileLocation);
return(GetExamFromByteArray(encrypted, studentPassword, sharedKeyIS, secLevel));
}
public static string GetExamFileWithoutSave(Exam anExam, string examKey, string sharedKeyIS, FilterationSecurityLevel secLevel)
{
try
{
//Serialize
var ser = Framework_Project.Serialization.SerializationHelper.Serialize(anExam);
//Add special string at loca{0-2} to check for description in the future
temp_ser = ser;
ser = "FCT" + ser;
if (secLevel == FilterationSecurityLevel.Moderate)
{
//compress before encryption is better to reduce size
var compressed = Framework_Project.Compression.CompressionHelper.Zip(ser);
//Encrypt using Exam Key
var encrypted = AESGCM.SimpleEncryptWithPassword(compressed, examKey);
return(encrypted);
}
else if (secLevel == FilterationSecurityLevel.High) //REMOVE DOUBLE ENCRYPTION FROM ALGO IN PAPER
{
//compress before encryption is better to reduce size
var compressed = Framework_Project.Compression.CompressionHelper.Zip(ser);
//Encrypt using student password SharedKeyIS
var encrypted = AESGCM.SimpleEncryptWithPassword(compressed, sharedKeyIS);
return(encrypted);
}
return(null);
}
catch (Exception ex)
{
throw new Exception("[Exception: Cannot Create exam in Exam Helper SaveExamToFile] [inner: " + ex.ToString());
}
}
public static bool ValidateExamCopy(string examCopy, string studentPassword, string sharedKeyIS, FilterationSecurityLevel secLevel)
{
try
{
var x = GetExamFromByteArray(examCopy, studentPassword, sharedKeyIS, secLevel);
return(true);
}
catch (Exception ex)
{
return(false);
}
}