Question 1

You are required to implement the following modes of operation: Electronic Codebook (ECB) Cipher Block Chaining (CBC) Cipher Feedback (CFB) Output Feedback (OFB) You may use any publicly available AES code or the AES code provided Blackboard. Provide the details of the source of the AES code that you use. Note that the implementation of the modes should be your own. [3 marks] Question 2 After implementation of these four modes, you are required to encrypt an image while preserving the image structure, i.e. apply AES only on the image data, keeping the header intact. Note that images encrypted while preserving image header should be viewable using standard image viewer applications (the content could be arbitrary). Criteria for choosing the input image is as follows: Compute the sum of characters of yourfirst nameand last namemodulo 26 (Characters are numbered from 0 to 25, A or a being 0 and Z or z being 25). Refer to the following ranges to determine which images to use for encryption: 0 – 8 : triangle.jpg 9 – 17: circle.jpg 18 – 25: rectangle.jpg The three images are provided in thedatafolder. Along with these images, you are required to select two more images from publicly available images of landscapes (keywords: landscape, beach, lake, mountains etc.) with visible repeated patterns. Choose images with size 800 x 600 pixels. Analyze the output of encryption using all four modes of operation and report your observations. [3 marks] Question 3 Analyze and report the error propagation properties of different modes of operations by performing the following tests (on all three images) as mentioned in Question 2: (a) Introduce an error in a cipher text block of the encrypted images. Analyze and report the number of blocks affected in the resulting decrypted plain text. Also, specify the particular block number you have corrupted. (b) Introduce an error in a plain text block of the images. Analyze and report the number of blocks affected in the resulting cipher text and the decrypted plain text. Report your results for all four modes of operation (ECB, CBC, CFB, and OFB) with all three images in your data set. Report the index position of the block you introduced the error in, number of blocks affected, the percentage error and your observations. You can compute the percentage error using the formula: Submission You must submit the following via UAlbany Blackboard:(a) Source code along with the instructions to run it.(b) A pdf file containing answers to Questions 2 and 3.(c) A video (of max 5 minutes) that shows the working of your program.


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