What is Cryptography? | How Codes Keep Information Safe

November 21, 2023

In an increasingly interconnected world, the safeguarding of sensitive information has become paramount. Cryptography, the art and science of securing data through encryption, has emerged as the cornerstone of our digital defence. From protecting online communications to securing financial transactions and beyond, cryptography plays a pivotal role in ensuring the confidentiality, integrity, and authenticity of data in the modern era. 

Defining Cryptography 

Cryptography, an ancient art rooted in the cryptic hieroglyphics of the Egyptians, is the practice of concealing information through intricate coding. The term itself, originating from the Greek words "kryptós" for hidden and "graphein" for writing, translates to "hidden writing." However, in practice, cryptography encompasses the secure transmission of information, drawing from diverse fields such as computer science, engineering, and mathematics to craft complex codes that obscure a message's true meaning. It uses techniques like cryptographic keys and digital signing to safeguard data privacy in scenarios ranging from credit card transactions to email exchanges and web browsing.

Modern cryptography has seen remarkable advancements, offering robust security. It serves as the guardian of information, ensuring that only those possessing the appropriate key can unveil its contents.

A Brief History of Cryptography

Cryptography boasts a rich and fascinating history, with codes and ciphers serving as guardians of secret messages for millennia. The earliest forms of classical cryptography emerged in ancient Egypt and Babylon, featuring substitution methods to transform plaintext into ciphertext and back. These early manual techniques remained relatively unaltered for centuries until the early 20th century ushered in a new era of cryptography. 

The advent of complex electromechanical machines brought about more advanced and efficient coding and decoding processes. The synergy between digital computing technology and cryptography accelerated progress, and in recent decades, public-key cryptography, incorporating digital signatures and distributed authentication, has paved the way for enhanced encryption protocols. This evolution has made cryptography not only more sophisticated but also widely accessible for personal and commercial use.

One of the earliest known cryptographic systems, the Caesar cipher, illustrates the fundamental principles of cryptography, involving algorithms and keys to reconstruct messages securely. Over time, encryption methods transitioned from simple substitution ciphers to complex techniques, with notable contributions from mathematicians and early computers. This ultimately expanded the role of cryptography from military and government domains to everyday life.

Cryptography and Encryption: What’s the Difference?

Cryptography and encryption are closely related yet distinct aspects of securing information. Cryptography, broadly defined as the science of sending secret messages, encompasses the overarching discipline of concealing information. It serves as a comprehensive framework for safeguarding data through a variety of techniques.

Encryption, on the other hand, represents the specific process of converting data into code, and it is an essential component within the realm of cryptography. It involves applying an algorithm, which dictates how the plaintext is transformed into ciphertext, and a key that is used to facilitate this transformation. Encryption, in essence, is a subset of cryptography and plays a pivotal role in ensuring data security. 

The Importance of Cryptography

Cryptography serves as a critical cybersecurity tool, offering a range of valuable features that are indispensable in today's digital world. One of its primary functions is to safeguard confidentiality, ensuring that only the intended recipient can access and read sensitive information. This confidentiality is achieved through encryption, where messages are transformed into indecipherable code using a secret key known only to the sender and recipient. Everyday tools like WhatsApp use this technique to protect conversations from hacking or interception. Additionally, cryptography plays a pivotal role in securing online browsing through technologies like virtual private networks (VPNs), which create encrypted tunnels and employ public and private keys.

Cryptography upholds the integrity of data, guaranteeing that encoded information cannot be altered or tampered with during transmission without leaving traces. Digital signatures, for instance, can detect any unauthorised modifications in software distribution or financial transactions, ensuring that data remains unaltered and trustworthy.

Authentication is another key feature of cryptography, verifying the identities of both sender and receiver, as well as confirming the origin and destination of information. This process ensures that communication occurs between legitimate parties, reducing the risk of impersonation or fraudulent interactions.

Cryptography also establishes non-repudiation, holding senders accountable for their messages. This means they cannot later deny sending the message or claim that it is fraudulent. Digital signatures and email tracking are effective tools in achieving non-repudiation, ensuring that the intentions of the sender cannot be disputed, and recipients cannot deny receiving a message.

Cryptography Within Cybersecurity 

Cryptography plays a critical role in the realm of cybersecurity. Its importance became evident with the rise of computers and open networks, where the need to protect information from interception and manipulation during transmission became imperative. Early pioneers like IBM introduced encryption in the 1960s, setting the stage for what would eventually become the first Data Encryption Standard (DES).

In today's digital landscape, cryptography serves as the linchpin for securing vast volumes of sensitive data. It finds real-life applications in various critical areas, such as:

  • Secured internet browsing: The use of virtual private networks (VPNs) and protocols like SSL and TLS enables safe and secure web browsing. Public key cryptography, employed by these protocols, encrypts data between web servers and clients, establishing a secure channel for communication.

  • Access controls: Cryptography aids in creating limited access controls, ensuring that only individuals with the correct permissions can carry out specific actions or access certain resources.
  • Protection of online communication: End-to-end encryption safeguards various forms of online communication, including emails, login credentials, and text messages through platforms like WhatsApp. This prevents unauthorised access to the content of these communications.

  • Defence against cyberattacks: Cryptography is instrumental in defending against cyberattacks, including the prevention of man-in-the-middle attacks.

  • Password security: Passwords are securely stored using cryptography techniques, ensuring that even if a hacker gains access to the password database, they cannot read the passwords.

  • Digital currencies: Cryptocurrencies like Bitcoin employ cryptography to secure transactions and prevent fraud. Complex algorithms and cryptographic keys protect transactions from tampering or forgery.

  • Electronic signatures: Digital signatures, created using cryptography, serve as the equivalent of handwritten signatures for signing documents. These signatures can be legally enforced and authenticated through public key cryptography.

  • Authentication: Cryptography is a cornerstone of authentication processes, confirming the user's identity and access rights in various scenarios, from bank account access to secure network usage.

  • End-to-End Encryption: It plays a pivotal role in protecting two-way communications, such as video chats, instant messages, and email. Services like WhatsApp use end-to-end encryption to ensure that only the intended recipients can read the messages, providing a high level of security and privacy.

Modern cryptography relies on rigorous analysis and mathematics to ensure security. It serves as the foundation of contemporary society, underpinning numerous internet applications, secure communication, and digital currencies, making it an essential component of our digital world.

Cryptographic Algorithms

Cryptography employs three distinct types of cryptographic algorithms, each with its own unique characteristics and applications:

  1. Symmetric Key Cryptography

In this encryption system, both the sender and the receiver utilise a single shared key for both encrypting and decrypting messages. Symmetric key systems are known for their speed and simplicity, but they face the challenge of securely exchanging the key between the sender and receiver. Prominent examples of symmetric key cryptography systems include the Data Encryption Standard (DES) and the Advanced Encryption Standard (AES). It's named "symmetric" because the same key is used for both encryption and decryption. This type of cryptography is well-suited for local data encryption, where the same user is responsible for both encrypting and decrypting the data.

  1. Asymmetric Key Cryptography

In asymmetric key cryptography, a pair of keys is employed for encryption and decryption. The recipient's public key is used for encryption, while the recipient's private key is used for decryption. The two keys are distinct, and even though the public key is known to everyone, only the intended recipient possesses the private key. The RSA algorithm is a widely recognised example of asymmetric cryptography, ensuring data confidentiality and authentication.

  1. Hash Functions

Hash functions are cryptographic algorithms that don't rely on keys. Instead, they generate a fixed-length hash value based on the plaintext's length, which is used to encrypt the data. Hash functions are widely used to protect passwords and ensure data integrity during encryption and decryption. They create a unique identifier for data, making it challenging to retrieve the original plaintext. 

These cryptographic types offer distinct advantages and serve various security purposes. Symmetric cryptography is suitable for local data protection and can be paired with asymmetric cryptography for secure internet communication. Hash functions guarantee data integrity and confidentiality, particularly in password protection. Asymmetric key cryptography provides a high level of security, enabling authentication and non-repudiation by confirming the sender's identity. The choice of cryptography type depends on the specific security needs and the nature of the communication.

Forms of Symmetric Key Cryptography

Within secret key cryptography, there are two primary types: stream ciphers and block ciphers. Stream ciphers work on individual bits or bytes of data and constantly modify the encryption key, either in a self-synchronising manner, where encryption and decryption stay in sync, or through synchronous generation, where the keystream functions independently of the message stream. 

Block ciphers, on the other hand, encrypt fixed-size data blocks, always producing the same ciphertext for a given key. An example of block ciphers is the Feistel cipher, which employs key expansion, permutation, and substitution to introduce complexity into the encryption process, focusing on one data block at a time. This approach simplifies the encryption and decryption stages, reducing the code size and circuitry required for implementing the cipher in software or hardware.

Forms of Asymmetric Key Cryptography

Among the different types of asymmetric key algorithms, RSA stands as a foundational solution, using factorisation as the basis for its encryption. The technique involves multiplying two large prime numbers to create a colossal, highly intricate number that defies decipherment. Elliptic Curve Cryptography (ECC), on the other hand, leverages elliptic curves in algebraic structures to construct complex algorithms. Notably, ECC excels in scenarios with limited computing resources, as it minimises storage and bandwidth requirements. 

Another prominent player is the Digital Signature Algorithm (DSA), recognised for its role in authenticating electronic signatures, and Identity-based Encryption (IBE). It eliminates the need for recipients to provide their public keys by using unique identifiers to generate public keys and corresponding private keys with the assistance of a trusted third-party server. 

Each of these asymmetric algorithms offers distinctive capabilities, contributing to the security and privacy of digital communications across a variety of applications.

Benefits of Cryptography For Your Business

Cryptography offers several advantages for your company in the realm of information security and data protection. Here are some key benefits:

  • Data confidentiality: Cryptography ensures that sensitive business information remains confidential and inaccessible to unauthorised individuals, reducing the risk of data breaches and leaks.

  • Secure communication: It enables secure communication channels, safeguarding internal and external data transfers, including emails, instant messaging, and file sharing.

  • Data integrity: Cryptographic techniques help verify the integrity of data, ensuring that information remains unaltered during transmission or storage.

  • Authentication: It plays a crucial role in authenticating users and devices, preventing unauthorised access to business systems and applications.

  • Compliance: Cryptography aids in meeting regulatory requirements and data protection standards, such as GDPR, HIPAA, and PCI DSS, reducing legal and financial risks.

  • Secure transactions: For businesses involved in online transactions, encryption is vital to protect financial information, fostering customer trust.

  • Protection against cyber threats: Cryptography defends against various cyber threats, including man-in-the-middle attacks, data interception, and unauthorised access.

  • Secure remote work: With the rise of remote work, cryptographic tools ensure secure access to business networks and sensitive data from remote locations.

  • Digital signatures: Cryptography facilitates the use of digital signatures, allowing businesses to verify the authenticity of digital documents and contracts.

  • Competitive advantage: Demonstrating a commitment to data security through strong cryptography can provide a competitive edge by enhancing customer trust and reputation.

Cryptographic Key Attacks 

Cryptographic keys are at the heart of encryption, and protecting them is paramount to ensuring data security. There are various types of cryptographic key attacks and potential issues to be aware of:

  • Weak keys: The strength and length of cryptographic keys are crucial. Longer keys with more random numbers are harder to crack. Key strength should match the data's value and the required protection duration. Quality random number generators are essential.

  • Incorrect key usage: Proper key usage is vital. Misusing or encoding keys poorly can weaken security, making it easier for hackers to break encryption.

  • Key reuse: Keys should be unique for each purpose. Using the same key for different systems diminishes the level of protection and compromises data security.

  • Key rotation: Cryptographic keys should be regularly updated to prevent them from becoming outdated, especially with older ciphers. Keys that encrypt too much data can become vulnerable and need to be rotated.

  • Inadequate key storage: Keys must be stored securely to prevent theft. Storing keys alongside the data they protect can lead to compromise, especially in the event of a data breach.

  • Insider attacks: Even employees with legitimate access can compromise keys. Insider threats can result in key theft and misuse.

  • Lack of backups: Backup keys are essential to ensure data accessibility in case primary keys become faulty.

  • Errors in recording keys: Manually entering keys into spreadsheets or writing them down on paper can introduce errors and vulnerabilities.

Specific cryptographic attacks aim to break encryptions by discovering the right key. These include:

  • Brute force attacks: These broad attacks attempt to randomly guess private keys using the known encryption algorithm.

  • Ciphertext-only attacks: Attackers intercept encrypted messages (ciphertext) and attempt to deduce the encryption key and plaintext.

  • Chosen ciphertext attacks: Attackers analyse ciphertext against its corresponding plaintext to deduce the key.

  • Chosen plaintext attacks: In these attacks, the attacker selects the plaintext corresponding to a ciphertext and begins decrypting it.

  • Known plaintext attacks: Attackers access part of both the plaintext and ciphertext to deduce the encryption key. This method is less effective with modern cryptography as it works better with simple ciphers.

  • Algorithm attacks: Cybercriminals analyse the encryption algorithm itself to deduce the encryption key.

Minimising Risks Tied to Cryptography

Minimising the risks associated with cryptography is essential for protecting sensitive data. A key management strategy forms the foundation of these risk-mitigation efforts. You can reduce the likelihood of cryptographic attacks by following key guidelines:

  1. Use distinct keys for specific purposes, like authentication and digital signatures, to limit the impact of key compromise.

  1. Employ robust key-encryption-keys (KEKs) to add an extra layer of security for cryptographic keys.

  1. Implement specialised hardware security modules (HSMs) to manage and safeguard keys effectively.

  1. Keep cryptographic keys and algorithms up to date to stay ahead of evolving threats.

  1. Encrypt all sensitive data to ensure protection even in the event of unauthorised access.

  1. Prevent third-party access to keys by storing them securely.

  1. Ensure the correct setup and implementation of cryptographic systems for maximum security.

  1. Include cryptography in security awareness training to promote best practices and awareness among staff.


Cryptography is an indispensable tool in our digital world, safeguarding sensitive information and ensuring privacy and security. Its evolution from ancient ciphers to complex algorithms reflects the ongoing battle between those who protect data and those who seek to compromise it. As technology continues to advance, cryptography remains a vital defence, assuring the confidentiality of our digital communications and transactions.

At ITRS, we make use of a host of tools, including cryptography to build solid cybersecurity approaches. Get in touch with us to find out how we can work with you to design a robust approach to protecting your company’s data and information. 

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