Code Recipes Blog

Under OTP, I showed with example how to generate an hotp.

By default the length of the hotp generated will be 6.

We can change that to any number between 6 and 8.

In this post under OTP, I will show with example how to change hotp length to 8.

Below is the complete main code for your reference.

Main Class

1  package defaultPackage;
2  
3  import com.bastiaanjansen.otp.HOTP;
4  import com.bastiaanjansen.otp.SecretGenerator;
5  
6  public class Example4 {
7      public static void main(String[] args) {
8          byte[] secret = SecretGenerator.generate();
9          HOTP.Builder builder = new HOTP.Builder(secret);
10         builder.withPasswordLength(8);
11         HOTP hotp = builder.build();
12         String otp = hotp.generate(1L);
13         System.out.println(otp);
14     }
15 }

In the above code, at line 9 we are creating an instance of “HOTP.Builder” class named “builder”.

At line 10, we are calling “withPasswordLength” method on the builder instance and passing 8 as an argument.

In this way we are changing the default otp length from 6 to 8 digits.