CWS - Foundations in Cryptography Lesson

Foundations in Cryptography

In this lesson, we will lay the groundwork for understanding the essentials of cryptography. Topics will include the historical context of cryptography, basic cryptographic concepts, and the role of cryptography in securing information. By the end of this lesson, you'll have a solid foundation in the principles that underpin secure communication.

 

History of Cryptography

History of Cryptography

Cryptography is the art of securing information and involves a set of fundamental concepts crucial to the world of secure communication. At its core, cryptography aims to protect information from unauthorized access by transforming it into an unintelligible form. Let's delve into the foundational elements of this fascinating field.

Cryptography is known as the art of encoding and decoding information. It has a rich history that stretches back to ancient civilizations. The roots of cryptography can be traced to the ancient Egyptians, who, around 1900 BCE, developed early methods of coding and decoding messages. Hieroglyphs, the intricate symbols used in Egyptian writing, served as the basis for their cryptographic system. The Egyptians recognized the need to secure certain communications, particularly those of a sensitive or confidential nature. Through the use of hieroglyphs and various substitution techniques, they pioneered some of the earliest forms of written codes. This early exploration into the protection of information laid the groundwork for the evolution of cryptography throughout history, demonstrating humanity's enduring quest for secure communication methods.

Historical Evolution of Cryptography: Unlocking the Past

Cryptography, the art and science of secure communication, has a rich history dating back to ancient civilizations. Each era contributed unique methods, laying the foundation for the sophisticated encryption techniques we use today. Let's embark on a journey through the historical evolution of cryptography.

 

Review the video on the History of Cryptography:

 

Exploring these historical milestones provides a fascinating glimpse into the evolution of cryptography, highlighting the innovative methods employed to protect sensitive information throughout the ages.

In the next section, we will review the secret languages and how coding and decoding messages were possible using encryption and decryption. We will also learn how to manage everything using hashing.

Plaintext and Ciphertext: The Language of Secrets

Every piece of information begins as plaintext – a human-readable message. However, this simplicity poses a vulnerability, making it essential to introduce cryptographic measures. Ciphertext, the encrypted form of plaintext, is the result of applying cryptographic algorithms. This transformation ensures that even if intercepted, the message remains indecipherable to those without the proper keys.

Encryption: Transforming and Safeguarding

Encryption is the process by which plaintext is transformed into ciphertext using cryptographic algorithms. This transformation serves as a shield against unauthorized access. The application of encryption is akin to placing a message inside a secure vault, accessible only to those with the appropriate key.

Decryption: Reverting to the Original

On the flip side, decryption is the process of reverting ciphertext back to its original plaintext form. This capability is reserved for authorized individuals possessing the necessary decryption key. Through this process, encrypted information can be securely accessed by those intended to receive it.

 

Symmetric and Asymmetric Encryption: Two Faces of Cryptographic Power

Symmetric Encryption:

Symmetric encryption relies on a single key for both encryption and decryption. This approach, while straightforward, requires secure key exchange methods. The simplicity and efficiency of symmetric encryption make it a valuable tool in cryptographic applications.

Diagram of a Symmetric Encryption

 

Watch the video below to learn more information about Symmetric Encryption.

 

Asymmetric Encryption:

In asymmetric encryption, a pair of keys – public and private – is used for encryption and decryption, respectively. The public key is widely distributed, while the private key is kept secure. Asymmetric encryption plays a vital role in secure communication, providing a robust method for data protection.

Diagram of an Asymmetric Encryption

Watch the video to learn more about Asymmetric Encryption. Take notes and compare and contrast the differences seen in the first video on symmetric encryption:

Understanding these basic cryptographic concepts is akin to learning the vocabulary of a new language. As we progress, you'll discover how these elements form the foundation for intricate cryptographic systems, ensuring the confidentiality and integrity of information in the digital realm.

In the expansive domain of cryptography, hashing stands as a stalwart defender of data integrity. This process involves a one-way transformation that generates a fixed-size output, commonly referred to as a hash value or digest. Crucially, this irreversible nature ensures that even the smallest alteration in the input results in a vastly different hash, establishing a robust method for data verification.

Hashing finds a primary application in crafting message digests, which are compact representations of data that facilitate efficient verification of data integrity. The inherent sensitivity of hash functions to any modification in the input ensures that a single bit change produces a substantially different hash, acting as an immediate alert for potential tampering.

Another pivotal role of hash functions is evident in the realm of digital signatures. By creating a hash of the message and encrypting it with the sender's private key, a digital signature not only validates the origin but also ensures the integrity of the message.

Despite its resilience, hashing encounters challenges from rainbow table attacks. These attacks involve precomputed tables containing hash values for commonly used passwords, enabling attackers to swiftly identify hashed passwords. To counter this risk, security measures such as salting are implemented.

In the practice of salted password hashing, a unique random value (salt) is introduced to each password before hashing. This strategy ensures that even if two users share the same password, their hashed values will differ due to individual salts. This countermeasure significantly diminishes the efficacy of precomputed tables, enhancing password security.

View the following video to learn more.

 

Review

Crypto Quote Challenge: Star Wars Edition

Decode the famous Star Wars quote encrypted using a simple substitution cipher.

Encrypted Quote:

Y - M / M - J - F / J - J / Y - J - J - A - Y - / Y - J - J - Y - R - F - J - J - F - Y - A / Y - M - / M - A - Y - / Y - F - J - R - Y - / J - J - F - Y - A - J - Y - / J - J - R - Y - F - J - Y - A - J

Instructions:

  • Each letter in the encrypted quote represents a different letter in the original Star Wars quote.
  • Utilize your knowledge of Star Wars quotes and the English language to decipher the hidden message.
  • Remember that spaces and punctuation remain the same in the encrypted message.
  • Once decoded, share the revealed Star Wars quote and discuss its significance or the character who said it.
  • May the Force be with you as you embark on this crypto quote challenge!

 

Cipher Key:

Original:   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Ciphered: Y M J F A I H U B O R L K Q V W X N S G D E P C T Z

Answer: THERE ARE TWO WAYS TO SLIDE EASILY THROUGH LIFE THE FIRST IS TO BELIEVE EVERYTHING THE SECOND IS TO DOUBT EVERYTHING

 

Review what you've learned in the activity below.

 

Reflection & Wrapup

In the fundamentals of cryptography lesson, we delved into the historical significance of cryptography, tracing its roots back to ancient civilizations, notably Egypt, where the foundations for securing information were established. We explored the fundamental concepts of plaintext and ciphertext, highlighting the essential transformation of human-readable messages into encrypted forms. Understanding the encryption and decryption processes emerged as a crucial aspect, with encryption serving as a protective shield and decryption enabling secure access to encrypted information. The distinction between symmetric and asymmetric encryption was emphasized, acknowledging the simplicity of symmetric methods and the enhanced security offered by asymmetric approaches. Overall, this lesson provided a solid foundation for comprehending the key principles of cryptography, laying the groundwork for more intricate cryptographic systems.

 

 

[CC BY-NC-SA 4.0 Links to an external site.] UNLESS OTHERWISE NOTED | IMAGES: LICENSED AND USED ACCORDING TO TERMS OF SUBSCRIPTION - INTENDED ONLY FOR USE WITHIN LESSON.

SYMMETRIC AND ASYMMETRIC ENCRYPTION DIAGRAMS BY MUNKHZAYA GANBOLD, CC BY-SA 4.0, VIA WIKIMEDIA COMMONS