What is cryptography? Cryptography types explained

What is cryptography?

Cryptography is the process of coding information to secure it and prevent unauthorized access. It involves using complex mathematical concepts to transform the original data (i.e., plaintext) into a format known as ciphertext. The ciphertext can’t be read without a decryption key.

Cryptography isn’t a new concept. Sophisticated methods of hiding information have existed in various cultures for several millennia. For example, cryptographic methods can be traced back to ancient Egyptians, who used hieroglyphics to protect sacred texts.

Cryptography is a crucial component of secure communications in modern times. Over the last few decades, cryptographic technology has evolved, leading to the development of advanced techniques, systems, and protocols to keep data safe. It is now largely adopted by businesses and organizations, including government agencies.

How does cryptography work?

Cryptography uses complex encryption algorithms to create a secure means of communication. In most cases, the cryptographic process involves scrambling the original (input) data to make it unreadable to anyone who doesn’t have authorization to access it. The text becomes unreadable unless you have a decryption key that transforms it back into its readable form.

One vital element of secure cryptography is the complexity of the algorithm used in the scrambling process. The more complex the algorithm, the stronger the data encryption, and the harder it becomes for hackers to access the information. Common examples include AES, Blowfish, and elliptic curve cryptography (ECC), which are widely applied in everything from password managers to secure messaging apps. The RSA algorithm, one of the first public key systems ever invented, remains widely used for secure data transmission today.

Three main types of cryptography exist. Let’s look at how they work, their differences, and how they’re used.

Types of cryptography

Modern cryptography can be divided into three types: symmetric and asymmetric cryptography, and hash functions. Let’s examine each type in more detail.

Symmetric key cryptography

Symmetric key cryptography, also known as secret key encryption, uses one key for the whole process. Both the sender and receiver use this same key to encrypt and decrypt a message they want to protect, meaning the key has to be securely shared between them.

This part of the process poses a potential vulnerability — having to exchange the key may mean cybercriminals have more opportunities to steal it and access the message. Because of this characteristic, symmetric key cryptography isn’t used as widely as asymmetric key algorithms. Unlike asymmetric key algorithms that use separate keys for encryption and decryption, symmetric systems rely on secure key distribution methods to function effectively.

Asymmetric key cryptography

Asymmetric key cryptography, or public key encryption, is often considered a more secure way to shield sensitive information than symmetric key cryptography. Asymmetric cryptography involves using two keys, a private key and a public key, to encrypt and decrypt data. Both keys are related — you need one to encrypt information and the other to decrypt it.

First, data is encrypted using the recipient’s public key, which is widely available on the network. To decrypt the data, the recipient needs to use their private key, which is only known to them. That way, only the intended recipient can decrypt the message — as long as their private key is kept safe.

Unlike symmetric cryptography, asymmetric encryption doesn’t require key exchange, meaning a cybercriminal has a smaller chance of stealing it during transmission. Systems that rely on asymmetric methods often use public key infrastructure (PKI) to manage certificates and ensure user authentication across networks. The beauty of public key systems is that the public key can be freely distributed without compromising security.

Hash functions

Hash functions are cryptographic algorithms used to protect sensitive information and its integrity. They process the information using a complex mathematical algorithm and produce a unique string of characters corresponding to the data. This string is known as a hash value, which is unique for each message. Even the slightest change in the input results in a different value. Commonly used examples include the SHA-256 (Secure Hash Algorithm 256) standard, which secures everything from blockchain transactions to password storage.

Hashing is particularly effective in authentication and ensuring data integrity. It may be used to securely store passwords in databases or to check the authenticity of digital signatures.

Unlike symmetric encryption and asymmetric encryption, hashing is a one-way process. You can produce a unique hash for input data, but decoding the data behind a hash value is impossible. That said, some hackers may launch brute-force and dictionary attacks to find an input that produces a specific hash value. That’s why it’s important to use strong cryptographic hash functions (and even additional measures like password salting).

Both hashing and encryption offer excellent security but are used in different ways. While data encryption scrambles your data to make it unreadable, hashing turns your information into a unique code that can’t be reversed. Read more on hashing vs. encryption and how these cryptography types differ in our article.

Cryptography features

When people talk about cryptography, they usually think of secret codes and scrambled text. But what really makes cryptography powerful are the features it brings to digital security. These features explain why cryptography is trusted to protect data, prove identities, and keep systems safe. Each of these features focuses on an important part of information security:

• Confidentiality. Cryptography ensures that only authorized parties can access the information. By turning readable text (plaintext) into unreadable code (ciphertext), cryptography ensures that sensitive data stays private whether it is stored, transmitted, or processed.
• Integrity. Guarantees that data has not been modified or tampered with. Hashing and digital signatures reveal if even the tiniest change has been made, protecting against tampering or corruption.
• Authentication. Confirms the identity of users, devices, or systems. Through digital certificates and cryptographic keys, authentication verifies that communications come from trusted sources.
• Non-repudiation. Prevents senders from denying their actions later. With features like digital signatures, cryptography provides proof that a message or transaction really came from its sender.
• Adaptability. Cryptography changes alongside technology, updating cryptographic algorithms to stay ahead of hackers and new types of attacks. This constant innovation keeps data protection strong.
• Interoperability. Cryptographic systems are designed to work across multiple platforms, networks, and applications, making secure communication possible no matter what systems are being used.

Cryptography application

Cryptography is one of the most important building blocks of digital security. It protects the systems we interact with daily, even if we don’t even notice it. Every time someone logs in to an account, shops online, or sends a private message, cryptography is quietly at work. Some of the most important applications of cryptography include:

• Passwords. When you create or enter a password, it is encrypted or hashed before being stored. This way, even if a hacker gets access to the database, they can’t easily read or steal the actual passwords.
• Secure web browsing (SSL/TLS). SSL and TLS use encryption to protect data shared between your browser and websites, preventing eavesdropping or man-in-the-middle attacks.
• Digital signatures. Cryptographic algorithms and public key systems make it possible to create digital signatures that prove the authenticity of a document or message and confirm that the content has not been changed.
• Authentication systems. Login processes and access controls use cryptography to verify identities and confirm user permissions.
• Cryptocurrencies. Digital currencies like Bitcoin and Ethereum rely on cryptography methods, including the Digital Signature Algorithm (DSA), to secure transactions, prevent fraud, and maintain trust in decentralized networks.
• End-to-end encryption. Many messaging apps use end-to-end encryption so that only the sender and receiver can read the messages, not even the service provider.
• Electronic payments and transactions. Online transactions use encryption to protect sensitive payment information and reduce the risk of fraud.

Advantages and disadvantages of cryptography

Cryptography is an essential component of cybersecurity and secure communication, and it’s what makes secure communication possible today. At the same time, cryptography is not without its challenges. Below are the main advantages and disadvantages of cryptography you might want to consider.

Cryptography advantages

Cryptography brings several strengths to digital security. Some of the biggest pros include:

• Data security. Cryptographic methods such as hash functions and digital signatures ensure that information cannot be tampered with by someone with malicious intent. A hash value allows systems to verify that data remains unchanged during transmission or storage.

• Confidentiality. Data is encrypted using symmetric or asymmetric key cryptography. Only users with the correct decryption key or a corresponding private key can access the original message, keeping sensitive data confidential and reducing the chances of it being compromised.

• Secure communication. Technologies like public key cryptography, transport layer security (TLS), and RSA encryption make it possible to communicate and exchange information more securely over the internet.

• Protection against cyberattacks. Strong cryptographic algorithms, such as the Advanced Encryption Standard (AES) or the older Data Encryption Standard (DES), help protect data from interception and may prevent certain attacks (e.g., ransomware and man-in-the-middle). 

• Legal compliance. Many laws and industry standards require encryption to protect sensitive information. Proper use of cryptography helps organizations meet GDPR, HIPAA, and other compliance frameworks.

Cryptography disadvantages

Like any technology, cryptography also has its limitations and risks. The most common drawbacks are:

• Implementation complexity. A robust cryptographic system requires careful design, secure cryptographic key generation, and proper key exchange methods. These requirements make them more difficult to implement and manage, which may make them less accessible to some organizations.

• Misuse by cybercriminals. Just as cryptography can protect data privacy, it can also be abused. Attackers use both encryption and decryption tools to hide stolen data, run ransomware operations, or exchange a secret code to coordinate crimes.

• Performance issues. Strong encryption algorithms like Advanced Encryption Standard improve security but may sometimes slow down data transfer speeds, causing internet connection issues. Even older standards like the Data Encryption Standard faced similar trade-offs between security and performance.

• Difficulty accessing information. If the private key or secret key is lost, even authorized users may not be able to decrypt data or messages in time, which can cause downtime or lost information.

The importance of cryptography

Cryptography makes the digital world trustworthy. It allows people and organizations to keep sensitive information safer and communication more private. Without it, daily activities such as online payments, private messaging, and secure file storage would be unreliable and unsafe.

Businesses rely on cryptography to ensure data privacy and meet legal security requirements. Regulations such as the GDPR and HIPAA make strong encryption a necessity, not an option. Cryptography also helps prevent fraud, data breaches, and identity theft — issues that can damage both customers and companies.

In financial systems, cryptography supports everything from digital signatures for contracts to cryptocurrencies like Bitcoin and Ethereum. It makes electronic transactions possible and gives people confidence that their money and personal details are protected.

Governments and critical industries also depend on cryptography. Military communications, healthcare systems, and infrastructure networks all use cryptographic algorithms, encryption keys, and secure communication protocols to reduce risks from cyberattacks.

Finally, cryptography is important for preparing for new challenges. Quantum computing could break many existing protections, which is why researchers are developing post-quantum cryptography. This work ensures that digital security will continue to hold even as technology changes.

Cryptography in cybersecurity

Cryptography plays a crucial role in cybersecurity. With everyone constantly exchanging information online, ensuring data integrity, authenticity, and confidentiality is paramount. That’s why cryptography is an important cybersecurity tool used by organizations globally.

In cybersecurity, cryptography is most closely linked to encryption. Using the same methods as cryptography, encryption scrambles data into a format that can’t be read without the right decryption key. This process safeguards sensitive information and helps prevent cyberattacks, data breaches, and unauthorized access.

Cryptography and VPNs

Cryptography and network security go hand in hand. A VPN (virtual private network) is a network security tool that secures your online traffic and hides your IP address. VPNs rely on cryptography to secure your internet connection.

A VPN uses cryptographic techniques to encrypt the online traffic traveling to and from your device, making it unreadable to snoopers and hackers. Even if these malicious parties manage to intercept your connection, your online traffic will look like gibberish, and they won’t be able to use it for malicious purposes. That’s how VPNs protect you from eavesdroppers, internet service providers, and anyone else who may want to look up your online activity.