Cryptography I

Go to Course: https://www.coursera.org/learn/crypto

Introduction

### Course Review: Cryptography I on Coursera In our increasingly digital age, understanding cryptography is not just for computer scientists but for anyone who wishes to understand how their information is protected. Coursera's "Cryptography I," taught by renowned experts, provides a deep dive into the principles and practices that underpin secure communication in the digital world. This course stands out for its structured approach and practical applications, making it a must-take for those interested in information security. #### Course Overview "Cryptography I" begins with the fundamental concepts of cryptography and progresses into more complex topics, ensuring students not only learn about theoretical frameworks but also gain hands-on experience through programming assignments. This course is divided into six weeks, each focusing on essential aspects of cryptographic systems, featuring comprehensive discussions about their real-world applications. #### Syllabus Breakdown 1. **Course Overview and Stream Ciphers (Week 1)**: The course kicks off with an introduction to cryptography, exploring foundational concepts like pseudo-randomness and secure encryption. Students will familiarize themselves with basic cipher standards, setting the stage for advanced topics later on. 2. **Block Ciphers (Week 2)**: Here, participants dive into the mechanics of block ciphers, including AES and 3DES. The optional programming assignment is an excellent opportunity for learners to develop a functioning encryption/decryption system, solidifying their understanding through practical application. 3. **Message Integrity (Week 3)**: This week focuses on data integrity, highlighting various constructions for MAC systems. The emphasis on practical projects, such as authenticating large video files, gives learners a chance to grasp important concepts like hash chains. 4. **Authenticated Encryption (Week 4)**: Students learn about authenticated encryption methods that ensure both confidentiality and integrity. The week also introduces networking concepts related to encryption, including an exciting extra credit project. 5. **Basic Key Exchange (Week 5)**: The focus shifts to how to establish a secure key exchange between two parties. This foundational knowledge sets up the transition into public-key cryptography, incorporating basic concepts from computational number theory. 6. **Public-Key Encryption (Week 6)**: The course culminates with an exploration of public-key encryption systems, particularly the RSA algorithm and the Diffie-Hellman protocol. Despite the increase in mathematical complexity, the course ensures support through forums, alleviating concerns about the steep learning curve. 7. **Final Exam**: The course wraps up with a comprehensive final exam, allowing students to gauge their understanding and retention of the material covered throughout the six weeks. #### Recommendations - **Who Should Take This Course?**: This course is ideal for students, professionals, or any tech-savvy individuals eager to enhance their understanding of cryptography. Whether you're in computer science, cybersecurity, or just interested in learning about information security, "Cryptography I" will provide invaluable insights. - **What You Will Gain**: By the end of the course, you will not only understand the theoretical underpinnings of cryptographic systems but will also possess practical skills to implement and analyze encryption protocols. This knowledge is crucial for safeguarding data in various real-world applications, from payment systems to secure messaging. - **Future Learning**: After completing "Cryptography I," students are encouraged to progress to "Cryptography II," which delves deeper into advanced topics, continuing their education in this fascinating and vital field. ### Conclusion Coursera's "Cryptography I" is a rigorous and rewarding course that equips learners with critical skills necessary for navigating the complexities of data security. Its blend of theory and practice, combined with the accessibility of an online format, makes it highly recommendable for anyone interested in cryptography. Enroll today and take the first step toward understanding the art and science of protecting information in our digital world!

Syllabus

Course overview and stream ciphers

Week 1. This week's topic is an overview of what cryptography is about as well as our first example ciphers. You will learn about pseudo-randomness and how to use it for encryption. We will also look at a few basic definitions of secure encryption.

Week 2. We introduce a new primitive called a block cipher that will let us build more powerful forms of encryption. We will look at a few classic block-cipher constructions (AES and 3DES) and see how to use them for encryption. Block ciphers are the work horse of cryptography and have many applications. Next week we will see how to use block ciphers to provide data integrity. The optional programming assignment this week asks students to build an encryption/decryption system using AES.

Week 3. This week's topic is data integrity. We will discuss a number of classic constructions for MAC systems that are used to ensure data integrity. For now we only discuss how to prevent modification of non-secret data. Next week we will come back to encryption and show how to provide both confidentiality and integrity. This week's programming project shows how to authenticate large video files. Even if you don't do the project, please read the project description --- it teaches an important concept called a hash chain.

Week 4. This week's topic is authenticated encryption: encryption methods that ensure both confidentiality and integrity. We will also discuss a few odds and ends such as how to search on encrypted data. This is our last week studying symmetric encryption. Next week we start with key management and public-key cryptography. As usual there is also an extra credit programming project. This week's project involves a bit of networking to experiment with a chosen ciphertext attack on a toy web site.

Week 5. This week's topic is basic key exchange: how to setup a secret key between two parties. For now we only consider protocols secure against eavesdropping. This question motivates the main concepts of public key cryptography, but before we build public-key systems we need to take a brief detour and cover a few basic concepts from computational number theory. We will start with algorithms dating back to antiquity (Euclid) and work our way up to Fermat, Euler, and Legendre. We will also mention in passing a few useful concepts from 20th century math. Next week we will put our hard work from this week to good use and construct several public key encryption systems.

Week 6. This week's topic is public key encryption: how to encrypt using a public key and decrypt using a secret key. Public key encryption is used for key management in encrypted file systems, in encrypted messaging systems, and for many other tasks. The videos cover two families of public key encryption systems: one based on trapdoor functions (RSA in particular) and the other based on the Diffie-Hellman protocol. We construct systems that are secure against tampering, also known as chosen ciphertext security (CCA security). There has been a ton of research on CCA security over the past decade and given the allotted time we can only summarize the main results from the last few years. The lectures contain suggestions for further readings for those interested in learning more about CCA secure public-key systems. The problem set this week involves a bit more math than usual, but should expand your understanding of public-key encryption. Please don't be shy about posting questions in the forum. This is the last week of this Crypto I course. I hope everyone learned a lot and enjoyed the material. Crypto is a beautiful topic with lots of open problems and room for further research. I look forward to seeing you in Crypto II where we will cover additional core topics and a few more advanced topics.

Congratulations! We are at the end of the course. This module contains only the final exam which covers the entire course. I hope everyone learned a lot during these 6 weeks. Good luck on the final exam and I look forward to seeing you at a future course!