Question

Am using the following program for generate the Token,based on the time(current time).It was work properly,It means the token will be generate.

         public string GenerateToken()
            {
                MD5 md5 = System.Security.Cryptography.MD5.Create();
                DateTime input = DateTime.Now;
                byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input.ToString());
                byte[] hash = md5.ComputeHash(inputBytes);

                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < hash.Length; i++)
                {
                    sb.Append(hash[i].ToString("X2"));
                }
                return sb.ToString();
            }

And I use the following program for try to lock(expire) the token with in 2 minutes.It means I access the GetToken() method, It will return the token for particular Time(current Time).I need to set valid time 2 minutes for that token.Incase I access the getToken() before 2 minutes I need to get the same token.But I access the getToken() after the 2 minutes i need to get new token. How can I do this?How do lock the token?

     public string GetToken()
        {
            DateTime currentTime = DateTime.UtcNow;               
            tokenExp = DateTime.UtcNow.AddMinutes(2);
            if (tokenExp >= currentTime)
            {
                token = GenerateToken();
                return token;
            }

            else lock (tokenLock)
                {
                    if (tokenExp >= currentTime)
                    {
                        token = GenerateToken();
                        //return token;

                    }
                    return token;
                }

Answer 1

You should be using something like below in GenerateToken method

 DateTime dateTime = DateTime.UtcNow;
 dateTime = dateTime.AddSeconds(-dateTime.Second);
 if (dateTime.Minute % 2 != 0)
     dateTime = dateTime.AddMinutes(1);

This will generate time with even minutes which is same for 2 minutes duration.

UPDATE

Full Code

public string GenerateToken()
{
    MD5 md5 = System.Security.Cryptography.MD5.Create();
    DateTime dateTime = DateTime.UtcNow;
    dateTime = dateTime.AddSeconds(-dateTime.Second);
    if (dateTime.Minute % 2 != 0)
        dateTime = dateTime.AddMinutes(1);

    byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(dateTime.ToString());
    byte[] hash = md5.ComputeHash(inputBytes);

    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < hash.Length; i++)
    {
        sb.Append(hash[i].ToString("X2"));
    }
    return sb.ToString();
}