Roy Sun, a 25-year-old Purdue University graduate, has received a four-year sentence for not attending classes and modifying all his grades to A's by hacking into his professor's computer. Sun will now spend 90 days of his sentence in prison and serve the rest of the days under supervised probation.

Dun first changed one of his grades in 2008. When officials failed to notice the grade alterations, Sun became confident and roped in fellow student Mitsutoashi Shirasaki to assist him in the crime.

"When I came back in 2009, I felt really arrogant. I thought I was untouchable," Sun said during his sentencing last week, according to the Journal and Courier. "It became so much easier to change my grades than going to class and working real hard."

During his senior year, Sun did not attend any classes but managed to receive good grades. Shirasaki and Sun corrected a grade for another student as well, Sujay Sharma, who kept a watch for his fellow students. Sharma was however unaware that his grades were being adjusted.

The two students installed keystroke logging devices onto professor's computers and subsequently hacked their personal information.

The investigators eventually found out about the grade-changing scandal. Sun lost his bachelor's degree and was dismissed from his graduate program at Boston University. The savvy trickster now works as a busboy.

"The most troubling thing about this is how brilliant you are and how capable your are to devise this and carry it out. ... I worry about people who are as bright as you who are as dishonest as you because you can do more damage," Judge Thomas Busch said, NY Daily News reports.

Both Sun and Sharma pleaded guilty Dec. 30. The mastermind got the severest sentence among the three for computer tampering and conspiracy to commit computer tampering. Sharma received three years probation for a count of conspiracy to commit computer tampering and assisting Sun and Shirasaki in the scandal. Meanwhile, Shirasaki fled to his native Japan at Sun's persistence and currently resides there.

When Sun asked if he would have a normal life after serving his full sentence, Busch said, "I don't think that your future is hopeless," Busch said. "I think you have the opportunity to rebuild your life and make your parents proud of you."