Encryption exercises. I've documented each solution to the best of my ability.

Encryption exercises public-key encryption scheme for single-bit messages. The book is divided into three parts. I have provided a word that will serve as the key. Aug 4, 2024 · Through hands-on exercises, we've explored the fundamental concepts of public and private key pairs, encryption and decryption processes, and the creation and verification of digital signatures. 1 (for example, TH or ST). You must figure out the koy in order to complete this section. hr Fully homomorphic encryption: Introduction and bootstrapping In today’s era of “cloud computing”, much of individuals’ and businesses’ data is stored and computed on by third parties such as Google, Microsoft, Apple, Amazon, Facebook, Dropbox and many others. Learning Outcomes: In this module, you will complete the following exercises: Exercise 1 - Encryption Exercise 2 - Hashing Exercise 3 - Obfuscation After completing this module, you should be able to: Encrypt a file. AES Example - Input (128 bit key and message) Key in English: Thats my Kung Fu (16 ASCII characters, 1 byte each) This page contains a selection of downloadable resources for teaching using cryptography. Improve your security knowledge with Python solutions for common security challenges. Exercise 8: Given a hardware implementation of the DES encryption function, what has to be modi ed to make it decrypt? 5 Modes of operation Exercise 9: In the CBC mode of operation, the initial vector (IV) is chosen uniformly at random, using a secure source of random bits. They're derived from weaknesses in real-world systems and modern Apr 24, 2025 · Practice your Python skills in cyber security with these exercises, including password hashing, generating random passwords, and checking password strength. Explore key concepts and practical examples to ace your Security+ certification exam. This is the more straightforward approach to data encryption, it is mathematically less complicated than public-key cryptography. An example of the program input and output is shown below: Enter a message: Hello world! Enter the distance value: 4 Homework exercises from the "Understanding Cryptography" textbook and accompanying lecture series. For this exercise. A Graduate Course in Applied Cryptography by D. I will edit the answer for clarifying that. It showcases key generation, message encryption/decryption, and digital signature verification, with clear code examples and file handling. The RSA method encrypts numbers rather than pieces of text. The goal is to ensure confidentiality and integrity in digital communications, with hands-on experience in key generation, encryption, decryption, and digital signatures. This is a different way to learn about crypto than taking a class or reading a book. To get you started: Easy - GXTW (Once you figure out the pattern to this, you can do the following): 3a. What is the vegetable? Exercise 3 A 2 2 Hill cipher encrypted the plaintext SOLVED to give the ciphertext GEZXDS. Columnar Transposition involves writing the plaintext out in rows, and then reading the ciphertext off in columns. 4 RSA Encryption RSA encryption is much more complicated than the encryption methods we have seen so far. These limitations include the lack of a standard comparison operator and certain operations that depend on it (like array max, histogram binning etc). 2 Exercise 5. Or upgrade to the Fun Pack for more fun activities! Hands-on lab exercise exploring the Vigenère cipher. Scott wants to understand what is cryptography and which part of the CIA Triad it affects. May 22, 2024 · PSCS 3107 Lab Exercise 4 1. Show how can it be used to encrypt a message once for two different recipients as Enc2(pkA, pkB, m). The solutions include formal definitions, descriptions of cryptographic algorithms and attacks, and proofs for some exercises. A cryptographic key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. You could just use trans-encryption to drastically reduce the transmission size, and then do your computation on the data as usual. Encryption In order to encrypt using the Playfair Cipher, we must first draw up a Polybius Square (but without the need for the number headings). One solution is d = 3 [ (3 * 7) % 20 = 1] Public key is (e, n) => (7, 33) Private key is (d, n) => (3, 33) The encryption of m = 2 is c = 27 % 33 = 29 The The Affine Cipher is a cipher that uses Maths to encode the message. Exercise 4: Frequency Analysis: A plaintext had its punctuation and spaces removed, and was then encrypted with a Caesar cipher. Use the AES tool (with the key 30 70 97 la b7 ce 45 06 3f d2 57 3f 49 f5 42 0d) to encrypt a block consisting of the following sentence “HelloWorldABCDEF”. Exercises: ECC-Based Asymmetric Encrypt / Decrypt (ECIES) Write a program to encrypt / decrypt a message by public / private key using ECIES (Elliptic Curve Integrated Encryption Scheme). Symmetric Encryption Lab [10 points] These exercises are based heavily on those developed at Seed Labs. The resulting ciphertext is: cxknxawxccxkncqjcrbcqnzdnbcrxwfruurjvbqjtnbynjan Use frequency analysis to identify which ciphertext characters are most common. Using a Cesar Cipher, shifting 3 letters to the right, encrypt the message Apr 24, 2025 · Practice your Python skills in cyber security with these exercises, including password hashing, generating random passwords, and checking password strength. In this exercise, you are required to conduct some AES encryption and decryption with the AES Tool mentioned in the preparation section. The strength of a cryptographic algorithm often depends not Through practical exercises, you will learn how to generate PGP key pairs, encrypt and decrypt messages, sign and verify files, and exchange encrypted emails. Exercises from Chapter 17 of the textbook: Exercise 44. E-Book Content Undergraduate Texts in Preface The following pages contain solutions to core problems from exams in Cryptography given at the Faculty of Mathematics, Natural Sciences and Information Technologies at the University of Primorska. Make games, apps and art with code. You will be quizzed on how it works and examples of it in use. In this lab, we will gain hands-on experience with OpenSSL by performing cryptographic operations. 3. In this Choose p = 3 and q = 11 Compute n = p * q = 3 * 11 = 33 Compute φ (n) = (p - 1) * (q - 1) = 2 * 10 = 20 Choose e such that 1 < e < φ (n) and e and φ (n) are coprime. Initial Setup Log in to your Virginia Cyber Range account and select the Today, computer users encrypt documents, network space, and e-mail messages as a way to protect the confidentiality of their messages. For any positive polynomial p , the function n e g l 4 defined by n e g l 4 ( n ) = p ( n ) · n e g l 1 ( n ) is negligible. The exercises focus on both symmetric and asymmetric encryption methodologies and provide practical implementation using tools such as Kleopatra and OpenSSL. Each team-member should complete the exercise as Bob, then pass along some information (but not the whole sheet!) to the other team-member, who will complete the exercise as Alice. About this Guided Project By the end of this project, you will be able to apply different decryption algorithms and techniques using Python. Find the encryption matrix. For theoretical background, see our algorithm and mathematical formula guide. The new types of encryption are very advanced, and sometimes complicated…. Execute JavaScript code. Shoup (free) Course syllabus, videos, and slides Jun 19, 2019 · Symmetric Key Ciphers Exercises: AES Encrypt / Decrypt In this exercise we shall encrypt and decrypt a text message using a symmetric cipher AES-CBC-256, combined with Scrypt password-to-key derivation and HMAC message authentication code. Why do we never let e be equal to 2? In this exercise, you will encrypt and decrypt numbers using a simple version of the RSA algorithm. 7 Exercise 5. A secret message M is encrypted with the Shift-Cipher using a secret key K. Tie-ins with algebra Frequency distribution Vigenere cipher Cryptosystem – an algorithm (or series of algorithms) needed to implement encryption and decryption. We discuss data con . 9 Exercise 5. Regev's Encryption Scheme. Here is a description of what you must do to use RSA encryption (a) Pick two large prime numbers p and q (b) Work out the products n = p £ q and k = (p ¡ 1) £ (q ¡ 1) Exercise 2 The matrix given in the last exercise was used as a key to a Hill cipher to encrypt a favourite vegetable of mine, and the resulting ciphertext was YGFI. This document is a solutions manual for the book "Introduction to Modern Cryptography - 2nd Edition". Jan 2, 2012 · Thus, the agenda for researchers was twofold: (1) come up with secure encryption schemes that could handle useful homomorphisms, and (2) figure out how to do interesting things with them. For any pair of users, say Alice (A) and Bob (B), G takes as input a string of random bits and produces as output a shared key KAB. 6. Exercises [2 points] Decrypt the following ciphertext that was encoded using a monoalphabetic substitution cipher. Exercise 4 of the secret key is known as a circular secure encryption scheme. Certificate Authority (CA): Both sites' certificates are likely issued by a well-known and trusted CA. We start with (a special case of) the famous \Leftover Hash Lemma" (Impagliazzo-Levin-Luby). , polynomials. The book goes into more depth, including security proofs, and many exercises. Exercise 13. Boneh and V. These About Exercises in Python notebook to implement the RSA encryption algorithm, and figure out if huge numbers are primes via Fermat test. In this series of videos, we walk through a series of different encryption and decryption classical cryptographic algorithms in Python code Oct 25, 2024 · The goal is to have an understanding and some exercises about Encryption and Decryption using CyberChef. Jonathan Katz and Yehuda Lindell, Introduction to Modern Cryptography, Second Edition Equivalence Theorem Theorem (Equivalence Theorem) A private-key encryption scheme is perfectly secure if and only if it is Shannon secure. Let be p = 7, q = 11 and e = 3. To be interesting, a homomorphic encryption scheme should at very least permit the evaluation of useful mathematical functions, e. 12 Exercise 5. The key is typically a large number that is used to mathematically transform the message. Aug 18, 2023 · Network Security: Data Encryption Standard - Solved QuestionsTopics discussed:1. But how to explain cryptography to a child? Here are some basic encryption & decryption activities along with a worksheet. Encryption involves Aug 22, 2022 · In my view, using such a small n in RSA exercises is ill-advised from a pedagogical standpoint, especially with no reminder that for RSA to be secure, a necessary condition is that n has hundreds decimal digits. But these are not always The operator of a Vigen`ere encryption machine is bored and encrypts a plaintext consisting of the same letter of the alphabet repeated several hundred times. Dec 27, 2024 · Master cryptography for Security+ with our Training Camp guide. In order to guard against transmission errors, Alice has Bob encrypt his message twice, once using the encryption exponent e 1 = 1021763679 and once using the encryption exponent e 2 = 519424709. GCM or CTR). Assume user B wants to send a confidential message to user A, where that message, M is 8. Oct 19, 2024 · Interactive Workshops and Simulations Workshops allow employees to participate in hands-on activities, such as handling phishing emails and data encryption exercises. In the modern day, computers help us write secret messages to protect our credit card information, personal information, and anything sent over the internet. Aug 11, 2025 · This comprehensive guide provides a complete Caesar cipher practice system with over 25 hands-on exercises, covering systematic training from basic manual encryption calculations to advanced cryptanalysis programming implementations and automated decryption techniques. Classically, cryptography provided solutions to protecting data in motion from point A to point B. Encrypt Message with RSA-OAEP You are given a text message and a RSA public key (in PEM format). Modern encryption techniques (e. Exercises 3. Numerous new exercises have been included. In this exercise, we will try to reconstruct Regev's public key encryption scheme. Pick out the most fre-quent ciphertext digram and assume it is the encryption of a common di-gram in the list following Table 2. In encryption and decryption processes, the key is what is used to encode or decode the message, making it unreadable to unauthorized parties. Exercise 9: In the textbook RSA encryption scheme, with n = pq being a product of two di erent primes and ed mod '(n) = 1, the identity med mod n = m, which states that we obtain the same plaintext m after encryption and decryption, is only guaranteed by Euler's theorem for any m 2 Zn, that is if gcd(n; m) = 1. This chapter provides details of Advanced Encryption Standard (AES), with concepts demonstrated via a simplified, educational version called Simplified Advanced Encryption Standard (S-AES). I've read Gentry's paper and use some websites like https://asecuri This repository contains solutions to programming exercises from Assembly Language for x86 Processors (8th Edition) by Kip Irvine. Encryption To encrypt a message using the Hill Cipher we must first turn our keyword into a key matrix (a 2 x 2 matrix for working with digraphs, a 3 x 3 matrix for working with trigraphs, etc). • Part I develops symmetric encryption which explains how two parties, Alice and Bob, can securely exchange information when they have a shared key unknown to the attacker. May 4, 2024 · About two years ago, I switched teams at Google to focus on fully homomorphic encryption (abbreviated FHE, or sometimes HE). Jun 12, 2025 · Python Exercises, Practice and Solution: Write a Python program to create a Caesar encryption. Related reading: Rosen p. A student should be able to complete this lab in one hour or less. In this tutorial we study FHE and describe its di erent properties, relations with other concepts in cryptography, and constructions. Exercise 3. It provides solutions to all the exercises in the book. When conver ng le ers into numbers, we use the following: The document contains exercises on cryptography topics including historic ciphers, perfect secrecy, semantic security, block ciphers, modes of operation, message authenticity, authenticated encryption, secure hash functions, secure hash applications, key distribution problems, and number theory and group theory. Question: TASK 3 (3 points ench, total 6 points) Here is another encryption/decryption exercise. But the idea is the same: you apply a “key” to some plaintext and transmit the resulting ciphertext. 1 Write a script that inputs a line of plaintext and a distance value and outputs an encrypted text using a Caesar cipher. Example-1: Step-1: Choose two prime number p p p and q q q Lets take p = 3 p = 3 p = 3 and q = 1 1 q = 11 q = 11 Step-2: Compute the value of n n n and ϕ \phi ϕ It is given as Homework Impossibility of perfectly-secure public-key encryption: Exercise 10. Keys play a critical role in the security of a cryptographic system. of the secret key is known as a circular secure encryption scheme. BMEG3120: Exercise List 11 Problem 1. If the data is encrypted, then it would be secure and About the exercise book This companion exercise and solution book to A Classical Introduction to Cryptography: Applications for Communications Security contains a carefully revised version of teaching material. Learn encryption and decryption techniques with a pre-encrypted message and create your own. “traditional” encryption techniques, the same key is used for enciphering (or encryption) and deciphering (or decryption). Not every encryption scheme is secure in this case, and actually in many cases it s not a good i ea to encrypt a sec ä Exercise 7. 1 in [KL]: Assume a public-key encryption scheme for single-bit messages. e. Instead, pairs of letters are translated into other pairs of letters. 26) on each vector. Check your understanding of cryptography and public key encryption, in this set of free practice questions designed for AP Computer Science Principles students. Implement a program to read the file, apply the encryption algorithm, and save the encrypted data to a new file. A Classical Exercise 8: Given a hardware implementation of the DES encryption function, what has to be modi ed to make it decrypt? 5 Modes of operation Exercise 9: In the CBC mode of operation, the initial vector (IV) is chosen uniformly at random, using a secure source of random bits. This exercise introduces students to the concept of public-key encryption, and to the RSA public-key cryptosystem (used by permission). Encrypt a folder. Find the ciphertext that B will send A. In ancient times, people had to write secret messages to keep messengers and interceptors from reading their private information. Dec 26, 2018 · Homomorphic Encryption for Beginners: A Practical Guide (Part 1) I will first go over the basics of homomorphic encryption, followed by a brief overview of the open source homomorphic encryption … Exercise 2 - Encrypt and Decrypt Data Overview of Exercise 2 Exercise 2 creates an AES secret key and uses it to encrypt some plaintext data. Can you reach the top of the leaderboard? Write a program to decrypt given encrypted message, produced by the previous exercise, using the RSA-KEM hybrid encryption scheme with AES symmetric encryption (use block mode of choice, e. Each team should have two members. Show that, given pk and a ciphertext c com-puted via c Encpk(m), it is possible for an unbounded adversary to determine m with probability Exercise 3: Provide a formal proof that if the Shift Cipher is modi ed so that a di erent key is chosen for each letter sent, then the result is a perfectly-secret encryption scheme. Let e = 7 Compute a value for d such that (d * e) % φ (n) = 1. - tombusby/understanding-cryptography-exercises Five REAL codes and ciphers that kids can use to send and receive secret messages. Spaces are encoded as spaces. The key is a six-letter English word. Solution This solution is verified as correct by the official Solutions for Odd-Numbered Jan 8, 2023 · encryption_ Creating Elliptic Curve Key Pairs In this example, we will use the elliptic curve algorithm to create a public/private key pair for encryption and decryption. We can encrypt data to protect it while it is in the different information states (transport, use, and storage) as we discussed with the McCumber Cube. Quiz & Worksheet Write a program to decrypt given encrypted message, produced by the previous exercise, using the RSA-KEM hybrid encryption scheme with AES symmetric encryption (use block mode of choice, e. 13. Note: This cipher uses both upper and lower case characters as well as punctuation. Decryption is the process of converting encrypted data back into its original form. About This Quiz & Worksheet This worksheet/quiz combo quickly tests your level of understanding of RSA encryption. Oct 29, 2018 · Complete the cryptography exercises from the College of Computing and Software Engineering at Kennesaw State University! A free, fun platform to learn about cryptography through solving challenges and cracking insecure code. Encryption is the process of hiding or transforming data into a secretive data - only the party that knows the key is able to restore the original message. For confidentiality, the sender encrypts using the receiver’s public key. PROPOSITION 3. This is usually done using a keyword, and either combining "i" and "j" or omitting "q" from the square. 3 Exercise 5. (Circular Security) Construct an encryption scheme that is secure, but it is not circularly secure. Solution 13. We give you problems to solve. Jul 11, 2025 · RSA algorithm is an asymmetric cryptography algorithm which means, there should be two keys involve while communicating, i. 6 Let n e g l 1 and n e g l 2 be negligible functions. Include both your source code and the required output into your answers. Want to practice coding? Try to solve this puzzle "Playfair Cipher" (25+ languages supported). The book is intended to be self contained. In this exercise, you should write a program that performs encryption and decryption under the Caesar cypher for an arbitrary key k. 1 Problem Prove Proposition 3. In this exercise you shall encrypt and decrypt messages using the RSA public-key cryptosystem. Encryption Level: The level of encryption (such as TLS 1. Follow Neso Columnar Transposition involves writing the plaintext out in rows, and then reading the ciphertext off in columns. I would like to express my sincere gratitude to Kip Irvine, the author of the book. We brie y discuss the three generations of FHE constructions since This course details the exploitation of a weakness in applications that rely on JSON Web Encryption (JWE) for authentication. Answer. What was the original plaintext? This exercise introduces students to the concept of public-key encryption, and to the RSA public-key cryptosystem (used by permission). Moreover, you will apply cryptography concepts through completing several practical exercises to build a solid foundation in decrypting information and data using several renowned industry encryption Apr 21, 2016 · Before starting the lab here are some definitions: In all symmetric crypto algorithms (also called Secret Key encryption) a secret key is used for both encrypt plaintext and decrypt the ciphertext. Plaintext which has been encrypted is referred to as ciphertext. What is the output? Mar 2, 2021 · Recently I'm researching about logical circuit calculation and I hope to use homomorphic encryption to protect the whole process. 2. 1. 12 Alice decides to use RSA with the public key N = 1889570071. fesb. Exercise 2: Confidentiality. 1 Decipher the message given above (in the grene theory ox). It was used by the authors or given as examinations to undergraduate and graduate-level students of the Cryptography and Security Lecture at EPFL from 2000 to mid-2005. Each such digram is the encryption of a plain-text digram using the unknown encryption matrix. Give a general algorithm for calculating d and run such algorithm with the above Anyone can learn computer science. The original plaintext is compared to- and is expected to be identical to May 11, 2018 · Return to index Exercise 5. Impossibility of perfectly-secure public-key encryption: Exercise 10. Jul 20, 2013 · TAGS encryption plaintext ciphertext task cryptool cipher fesb encrypted length ciphers laboratory exercises symmetric asymmetric cryptography marjan. Explanation provided via comments in Japanese. b Exercise 2. We have talked about the security triad several times in the course. Public Key Encryption Schemes Describe a variant of ElGamal encryption in which the encryption function is Enc(pk, m) = (grm, yr) instead of the original one Enc(pk, m) = (gr, yrm). 2 (RSA Encryption for Confidentiality). 11 Exercise 5. There are simple steps to solve problems on the RSA Algorithm. @Dillinur I merely put it as an example. 502 mod 1961 = 539 504 mod 1961 = 5392 mod 1961 = 293 508 mod 1961 = 2932 mod 1961 = 1526 5016 mod 1961 = 15262 mod 1961 = 969 5032 mod 1961 = 9692 mod 1961 = 1603 Therefore, 5045 mod 1961 = 5032 ·508 ·504 ·50 mod 1961 = 1603·1526·293·50 mod 1961 = 1412. Download the free encryption and decryption tools. Arguments, input and output Your program will be run with a numeric k indicating the encryption/decryption key. I thoroughly enjoyed reading it and About This repository contains cryptographic exercises demonstrating symmetric encryption using the Fernet algorithm and asymmetric encryption/signing with RSA. Apr 24, 2025 · Python Cyber Security - Learn how to create a Python function that can take a password string and convert it into a secure SHA-256 hashed representation in hexadecimal format. Textbook: The following is a free textbook for the course. Show that, given pkand a ciphertext ccom- puted via c←Encpk (m), it is possible for an unbounded adversary to determine mwith probability 1. , RSA and AES) are much more sophisticated than the shift ciphers we’ve looked at in this exercise. Welcome to the challenges We can't introduce these any better than Maciej Ceglowski did, so read that blog post first. Apr 1, 2025 · Cryptography can be a brain teasing fun activity for kids. You should Nov 16, 2019 · I have doubts about this question Consider the following textbook RSA example. In the Playfair cipher, there is not a single translation of each letter of the alphabet; that is, you don’t just decide that every B will be turned into an F. The model answers use Perl (see Part IB Unix Tools course), but you can use any language you prefer, as long as it supports an arbitrary-length integer type and o ers a SHA-1 function. Overview This individual laboratory exercise will provide some hands-on experience with cryptography primitives and cipher block modes of operation on a Linux system. 10 Exercise 5. 3. 2 (10 reviews) Save 4. Chapter 4 Programming Exercises 4. Many sections have been rewritten or expanded for clarity, especially in the chapters on information theory, elliptic curves, and lattices, and the chapter of additional topics has been expanded to include sections on digital cash and homomorphic encryption. 1 Exercise 5. Then, The function n e g l 3 defined by n e g l 3 ( n ) = n e g l 1 ( n ) + n e g l 2 ( n ) is negligible. Exercise 7 – Double Ciphering Suppose you encrypt using an affine cipher, mx+n, then encrypt the encryption using another affine cipher, ax+b (both modulo 26). Cryptography Worksheet People have always been interested in writing secret messages. In this way, both team-members will play both roles in the exercise. 4 Exercise 5. (Now is a great time to pause to review the steps of the RSA algorithm!!) We proved that RSA encryption and decryption work correctly when the (integer) message m is coprime to the modulus n. Shoup (free) Course syllabus, videos, and slides Exercises: Encrypt / Decrypt Messages using RSA In this exercise you shall encrypt and decrypt messages using the RSA public-key cryptosystem. The script should work for any printable characters. Input: First line: the input message Next few Jun 19, 2019 · Asymmetric Key Ciphers Exercises: ECIES Encrypt / Decrypt Write a program to encrypt / decrypt a message by public / private key using ECIES (Elliptic Curve Integrated Encryption Scheme). By understanding the structure and encryption methods of JWE tokens, you will learn how to forge tokens and gain unauthorized access. pdf from CPSC 1050 at Langara College. Secret key algorithms use the same key for both encryption and decryption (or one is easily derivable from the other). Some of the exercises require the implementation of short programs. View Encryption Exercises (1). 3: Encryption is deterministic so one can compare the challenge ciphertext c with me Exercise 8: Given a hardware implementation of the DES encryption function, what has to be modi ed to make it decrypt? 5 Modes of operation Exercise 9: In the CBC mode of operation, the initial vector (IV) is chosen uniformly at random, using a secure source of random bits. 2 Write down the decryption key for the following transposition encryption key k = (3;1;2). This ciphertext is then decrypted back into plaintext using the same AES secret key that was used for encryption. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages; various aspects in information security such as data confidentiality, data integrity Exercise 1 (Shift-Cipher). Write a program to encrypt the message, using the RSA-OAEP encryption scheme (RSA + PKCS#1 OAEP padding). Cryptography is the practice of techniques for secure communication in the presence of third par-ties. CSC110 Chapter 8 Practice: The RSA Cryptosytem, Proofs and in Practice Print this handout Exercise 1: Completing the proof of RSA correctness In lecture, you learned about the RSA cryptosystem. Resources required This exercise requires the Ubuntu with Snort and Other Tools exercise in the Virginia Cyber Range. Exercise 1: Cryptography. Many of the details serve mainly as reference, with little discussion. Obfuscate and execute JavaScript code. An example of the program input and output is shown below: Enter a message: Hello world! Enter the distance value: 4 Proxy re-encryption is just a specific use-case. Some supplementary material covering basic facts from probability theory and algebra is provided in the appendices. Definition Cryptography or cryptology is the practice and study of techniques for secure communication in the presence of third parties called adversaries. Calculate 5045 mod 1961. You’ll learn how to encrypt and decrypt data with various cipher modes, and understand how to manage encryption contexts through OpenSSL’s EVP API. , public key and private key. This project investigates a cipher that is somewhat more complicated than the simple substitution cipher of Chapter 11. For our purposes, the words encrypt and encipher will be used interchangeably, as will decrypt and decipher. g. Conduct hashing in Windows. For example, the plaintext "a simple transposition" with 5 columns looks like the grid below Exercise 8: Given a hardware implementation of the DES encryption function, what has to be modi ed to make it decrypt? 5 Modes of operation Exercise 9: In the CBC mode of operation, the initial vector (IV) is chosen uniformly at random, using a secure source of random bits. Step 1. Dec 9, 2024 · Abstract An exercise in implementing Scale Invariant Feature Transform using CKKS Fully Homomorphic encryption quickly reveals some glaring limitations in the current FHE paradigm. The problem then becomes the secure transmission of the key itself. The goal of this lab is to learn how to generate cryptographic keys Take-home exercise: using the Vigenère cipher Think of a long but easy to remember pass phrase, something like “My uncle’s name is George. We can distinguish two kinds of symmetric cryptographic algorithms: Classic and “traditional” encryption techniques, the same key is used for enciphering (or encryption) and deciphering (or decryption). The solutions are intended for instructors using the book, and the authors ask to keep the solutions confidential. It works by conver ng every le er in the alphabet into a number, performing a func on on that number, and turning the result back into a le er. 3) is likely to be similar, as these are currently the most secure and widely used versions of SSL/TLS. We also turn the plaintext into digraphs (or trigraphs) and each of these into a column vector. Chapter 1: Introduction 1. All arithmetic operations in this exercise are performed modulo q. We let n be some natural number, and q n be some natural number to be used as modulus. Record the output of the encryption in Hex. The encryption will require an EC public key and decryption will require the corresponding EC private key. 294 Exercise 2. In this exercise, you will explore symmetric encryption using OpenSSL in C. RSA Practice Problems Important! These are all exam-level problems. Do not attempt these problems without a solid foundation in the subject and use them for exam practice. 2 or TLS 1. 6 Exercise 5. Students are asked to implement solutions to the exercises in a programming The purpose of this document is to describe a verification exercise that consists on performing the security proof of the ElGamal encryption scheme in its hashed version. If you’ve heard about FHE and you’re a software person, you’ve probably Nov 6, 2022 · 1. 5 Describe how the OFB mode can be attacked if the IV is not different for each execution of the encryption operation. 1 in [KL]: Assume a 10 p. Choose " AES Encrypt " as the encryption operation, and type " Hello, welcome to AES encryption! " . Eve intercepts the two encrypted messages c 1 =1244183534 and c 2 =732959706. This is your encryption key. ” Write it in all capitals and without spaces or punctuation. Since then I’ve got to work on a lot of interesting projects, learning along the way about post-quantum cryptography, compiler design, and the ins and outs of fully homomorphic encryption. In this exercise we shall encrypt and decrypt a text message using a symmetric cipher AES-CBC-256, combined with Scrypt password-to-key derivation and HMAC message authentication code. Exam Objectives: The following exam Practice Questions for Exam 1 (Crypto Basics) Question 1-Crypto: Recall that a symmetric-key cryptosystem consists of three functions: a key generator G, an encryption function E, and a decryption function D. This exercise is essential for understanding how confidentiality is maintained in secure communications. Conduct hashing in Linux. When k argument is not given as a command line argument, assume it to be 13. I've documented each solution to the best of my ability. In its simplest form, it is the Route Cipher where the route is to read down each column in order. 8 Exercise 5. 5 Exercise 5. In fact we shall implement a password-based symmetric authenticated encryption scheme. The secret key can be a number, a word, or a string of random letter, once applied to a given data (message, text). Aug 16, 2025 · Learn how to use C++ file handling to encrypt the contents of a text file using a simple encryption algorithm. Exercise 8: Given a hardware implementation of the DES encryption function, what has to be modi ed to make it decrypt? 5 Modes of operation Exercise 9: In the CBC mode of operation, the initial vector (IV) is chosen uniformly at random, using a secure source of random bits. We then perform matrix multiplication modulo the length of the alphabet (i. Five solved examples based on the Data Encryption Standard (DES). We've built a collection of exercises that demonstrate attacks on real-world crypto. For example, the plaintext "a simple transposition" with 5 columns looks like the grid below Description easy COMPUTER SCIENCE - Encryption (Infotext and Exercises) The material contains a worksheet with an information text and various exercises related to the text, such as matching tasks, multiple-choice questions, open questions and true-false questions. We've seen how asymmetric cryptography solves key distribution challenges and offers enhanced security features like authenticity and non-repudiation. Jul 30, 2025 · Symmetric algorithms use the same key for encryption and decryption (or the decryption key is easily derived from the encryption key). We have set out a number of exercises for you to do; decryptions and encryptions based on a Caesar cipher and a permutation cipher. This lab will provide all the essential skills for using PGP for secure communication and data protection. Fully homomorphic encryption (FHE) has been called the \Swiss Army knife of cryptog-raphy", since it provides a single tool that can be uniformly applied to many cryptographic applications. Introduction to OpenSSL: A Hands-On Lab using OpenSSL and encryption OpenSSL is a widely used open-source software library that provides cryptographic functions and protocols to secure communications over computer networks. Mr. but, the basic skill remains true to the ancient methods! Below you will find a collection of links on cryptology use through history. If you encounter any issues or have feedback, please don't hesitate to let me know. vvwtla czagz oclcbrh eajelp hmwps xtlxf kacdp dwe ogen ybjuus ldcluve qgsx yqm chgvcrg iwow