About Captcha

"Completely Automated Public Turing test to tell Computers and Humans Apart"

Prevent from :

• Spam/SpamBot
• DOS/DDOS
• etc

Captcha Types

"Which digit is 1st in the number 4581944?"

Breaking Captcha

 

• Captcha Vuln. -- > Session ID / Cookies

• OCR -- > Tesseract OCR / OpenCV

  • Removing Noises --> PIL

  • Separating Characters

  • Extracting Features

  • Classifying Features

• OCR -- > Tesseract OCR / OpenCV

Deep Learning Toolchain

• Theano
• Torch
• TensorFlow
• Caffe/Caffe2
• PyLearn
• Singa
• Deeplearning4J
• Keras
• ...

Compare

Theano A CPU and GPU Math Compiler in Python

• Base on Numpy

• Implemented by Cython

• Dynamic C code generation

• GPU & CUDA

Keras is a high-level neural networks API, written in Python and capable of running on top of either TensorFlow or Theano.

• Allows for easy and fast prototyping (through user friendliness, modularity, and extensibility).

• Supports both convolutional networks and recurrent networks, as well as combinations of the two.

• Runs seamlessly on CPU and GPU.

Recognise Direct

• Dataset : Generate Captcha  --> python Captcha
• Build Model : CNN --> Keras + Theano Backend
• Training
• Predict

 > No Captcha

       > spec.py

       > gen.py

       > load.py

       > model.py

       > train.py

       > pre.py

No Captcha Structure

 > No Captcha

       > spec.py

              > Captcha Format(Num,Alpha,Length,Size)

       > gen.py

              > Generate Random Text Based on Spec

              > Generate ImageCaptcha Based on Text

              > Labeling By Text and Save

       > load.py

              > Text2Vec Func. (Captcha Text To Vector Array)

              > Loading Dataset (Pre Proccess Image)

                    > Split to train/test Data

       > model.py

                    > Building CNN Model

                    > Create Weight File

       > train.py

​                    > Input Data parameters

​                    > Training with th backend : train Data

​                    > Calculate Accuracy : test Data

       > pre.py

​                    > Load Trained Model

​                    > Lookup in Trained Model for textvec of Captcha

​                    > Return Text of Captcha