Enhancing Security in Cloud Computing using Two-Tier CAPTCHA

ByKarthik Balasubramanian

Prateek Basavaraj

Introduction

• Cloud computing has many advantages like broad network access, cost effectiveness, rapid elasticity, energy saving, resource pooling and reliability.

• Cloud computing is suffering from some drawbacks like security and privacy.

• Distributed denial of service attack is biggest threat in cloud computing, where attackers prevent legitimate users using desired resources.

Proposed Solution

• CAPTCHA -Completely Automated Public Turing Tests to Tell Computers and Humans Apart

• CAPTCHA is used for graphical turing test.

• Many OCR and Non OCR based CAPTCHA's are prone to many attacks.

• In our project, we are using two-tier CAPTCHA.

CAPTCHA

• Program that can generate and grade tests that humans can

pass but computer programs cannot

Applications:

Preventing Comment Spam in Blogs

Preventing Dictionary Attacks

Search Engine Bots

Online Polls

Two-Tier CAPTCHA

• In this new method, CLAD node need to generate two

things

• Alphanumeric CAPTCHA and CAPTCHA code with

image

• Second query related to CAPTCHA code

• Method makes hard for bot programs

Algorithm

• Create a random alphanumeric code

• Create image with some noise containing that code

• Select random query related to that code

• Keep combination of code and query in session

• Set CAPTCHA Image onto the user interface page

along with Query

Algorithm(Continued)

• Allow user to provide input

• Compare Input provided by user with value stored in

session

• Correct input - Allow user to proceed and Delete the

used CAPTCHA Image

• Incorrect input – Provide another CAPTCHA image and

give limited chances

THANK YOU