Genarate One Time Password String.

In this blog you will learn how to write code which will help you in generation of OTP which is now used very widely for authorization.

OTP is very widely used for authorization now a days. Following code will help you to generate a random string which can be use full for you to generate OTP string.

 

public static string TOTPGenerator(string uniqueIdentity)

{

string oneTimePassword = "";

DateTime dateTime = DateTime.Now;

string _strParsedReqNo = dateTime.Day.ToString();

_strParsedReqNo = _strParsedReqNo + dateTime.Month.ToString();

_strParsedReqNo = _strParsedReqNo + dateTime.Year.ToString();

_strParsedReqNo = _strParsedReqNo + dateTime.Hour.ToString();

_strParsedReqNo = _strParsedReqNo + dateTime.Minute.ToString();

_strParsedReqNo = _strParsedReqNo + dateTime.Second.ToString();

_strParsedReqNo = _strParsedReqNo + dateTime.Millisecond.ToString();

_strParsedReqNo = _strParsedReqNo + uniqueCustomerIdentity;

//Append above string with Policy number to get desired output.

Console.WriteLine("TOTP value: " + _strParsedReqNo);

using (MD5 md5 = MD5.Create())

{

//Get hash code of entered request id in byte format.

byte[] _reqByte = md5.ComputeHash(Encoding.UTF8.GetBytes(_strParsedReqNo));

//convert byte array to integer.

int _parsedReqNo = BitConverter.ToInt32(_reqByte, 0);

string _strParsedReqId = Math.Abs(_parsedReqNo).ToString();

//Check if length of hash code is less than 9.

//If so, then prepend multiple zeros upto the length becomes atleast 9 characters.

if (_strParsedReqId.Length < 9)

{

StringBuilder sb = new StringBuilder(_strParsedReqId);

for (int k = 0; k < (9 - _strParsedReqId.Length); k++)

{

sb.Insert(0, '0');

}

_strParsedReqId = sb.ToString();

}

oneTimePassword = _strParsedReqId;

}

//Adding random letters to the OTP.

StringBuilder builder = new StringBuilder();

Random random = new Random();

string randomString = "";

for (int i = 0; i < 4; i++)

{

randomString += Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65)));

}

//Deciding number of characters in OTP.

Random ran = new Random();

int randomNumber = ran.Next(2, 5);

Random num = new Random();

//Form alphanumeric OTP and rearrange it reandomly.

string otpString = randomString.Substring(0, randomNumber);

otpString += oneTimePassword.Substring(0, 7 - randomNumber);

oneTimePassword = new string(otpString.ToCharArray().OrderBy(s => (num.Next(2) % 2) == 0).ToArray());

return oneTimePassword;

}

 

 

Hope this will help full for you guys.

Thank you.