Kuromori Kabuki – Yamagata Prefecture’s Intangible Cultural Heritage. A performance with a lecture
Every day, we send messages, log in to our bank accounts, make payments with our phones, and share data with cloud-based apps. Most of these activities would not be secure without mechanisms that users usually don’t even notice. Cryptography—a field that combines mathematics, computer science, and security engineering—is responsible for protecting information in many systems.
Although it is primarily associated with converting legible text into an unintelligible form, its role is much broader. Modern cryptographic solutions help not only to conceal the content of data, but also to detect tampering, verify the origin of a message, and securely establish the identity of users and devices.
What is cryptography?
Simply put, cryptography is a set of methods used to protect information through mathematical transformations. Plaintext data can be processed by an algorithm into an encrypted form. A person or system with the appropriate authorization can then reverse this operation and recover the original content.
However, the answer to the question of what cryptography is should not be limited to encryption alone. Its most important functions include:
- confidentiality – the information remains inaccessible to unauthorized persons,
- integrity – you can verify that the data has not been altered,
- authentication – it is possible to verify the identity of an entity or the origin of information,
- non-repudiation – the author of a transaction cannot easily deny having performed it if an appropriate signature mechanism has been used and the keys have been properly protected.
Cryptography, therefore, provides the tools that form the technical foundation of trust in the digital environment. The U.S. National Institute of Standards and Technology explicitly states that cryptographic techniques use mathematics to secure information and are used, among other things, in communications, mobile devices, and electronic transactions.
How does data encryption work?
In a simplified model of encryption, there are three elements: input data, an algorithm, and a cryptographic key. The algorithm defines the rules for transforming the information, while the key determines the specific result of the operation. The same algorithm used with a different key will produce a different ciphertext.
This can be compared to many identical safes equipped with different locks. The design of each safe works on the same principle, but opening a specific safe requires a matching key. Security, therefore, should not depend on concealing how the algorithm works. In mature solutions, it is the key that remains the protected element of the system.
Keys must be properly generated, stored, transmitted, renewed, and revoked. Even a strong algorithm will not provide protection if the key is stored in a publicly accessible repository, transmitted over an unsecured channel, or left on a device without proper security measures. Key management is therefore just as important as the choice of the cryptographic method itself.
Symmetric cryptography, which uses a single secret key on both sides
Symmetric cryptography uses the same secret key to encrypt and decrypt data. The sender and recipient must first obtain a shared secret key and effectively protect it from being intercepted.
The biggest advantage of this approach is performance. Symmetric algorithms work well for protecting large amounts of information, which is why they can secure files, backups, disks, and data transmitted over an active connection. AES is a widely used standard in this category.
The challenge arises when securely exchanging a key. If the two parties do not yet have a secure communication channel, they must agree on a shared secret key by other means. In a system supporting multiple users, the number of keys that need to be managed also increases. For this reason, symmetric cryptography is often used in conjunction with asymmetric solutions.
Asymmetric cryptography, or public and private keys
Asymmetric cryptography is based on a pair of mathematically related keys. The public key can be shared, while the private key should remain under the sole control of its owner. Operations performed using one key in the pair are verified or completed using the other.
If someone wants to send encrypted information to a recipient, they can use the recipient's public key. Decrypting the data then requires the corresponding private key. A different field of study application arises in digital signatures, where the owner uses a private key to sign the data, and others verify the signature using the public key.
The asymmetric approach facilitates the establishment of secure communication between parties who have not previously agreed on a shared secret key. However, it requires more computational resources than symmetric encryption. In practice, therefore, both models are combined. Asymmetric mechanisms help authenticate a party and establish the key material, while fast symmetric algorithms secure the subsequent transmission.
| Feature | Symmetric Cryptography | Asymmetric Cryptography |
| Number of keys | One shared secret key | Pair: public and private keys |
| Performance | High, suitable for large datasets | Lower due to more complex calculations |
| The Main Challenge | Secure Distribution of a Shared Key | Protecting the private key and verifying who owns the public key |
| Typical Application | Encryption of files, drives, and data transmissions | Key exchange, digital signatures, and authentication |
More Than Just Encryption—Hash Functions and Digital Signatures
A hash function transforms data of any length into a fixed-size result, called a hash. It is designed as a one-way operation; it should be practically impossible to reconstruct the input data from the hash alone. Even a minor change to the document, however, should result in a different hash.
These properties allow for the verification of file integrity, support the secure storage of passwords, and are used in the creation of digital signatures. In authentication systems, a password should not be stored in plain text or simply encrypted. Typically, the output of a carefully chosen, deliberately slow hash function is stored along with a unique additional value called a salt.
A digital signature combines asymmetric cryptography with a hash function. It allows one to verify that the content has not been altered since it was signed and that the signature was created using a private key corresponding to the specified public key. However, a digital signature should not be confused with confidentiality. A signed document does not automatically become confidential; encryption is required to conceal its contents.
Cryptography in a Zero Trust Approach
In the traditional security model, the organization’s network perimeter was of great importance. However, modern environments include the cloud, remote work, mobile devices, and services provided by multiple partners. The mere fact that a user is “inside” the network should therefore not be the sole determinant of trust.
The Zero Trust model involves continuous access verification, privilege reduction, and preparedness for potential security breaches. Cryptography supports this approach through the protection of data in transit and at rest, certificates, digital signatures, and authentication mechanisms. However, it does not replace access controls, monitoring, network segmentation, or proper incident response.
Does cryptography help in the world of deepfakes?
Advances in generative artificial intelligence mean that a voice recording or a facial image are not always sufficient proof of identity. In the age of deepfakes, we therefore need multi-channel verification, access control, and content provenance checks.
Cryptographic mechanisms can facilitate the verification of a file’s history and the detection of changes made after it was signed. However, it is important to understand their limitations. A valid signature confirms the association of the data with a specific key and its integrity, but does not in itself prove that the content represents a true event. If fraudulent material is signed by an authorized but poorly secured system, mathematically correct verification will not resolve the problem at an earlier stage.
What will quantum computers change?
Some modern asymmetric algorithms base their security on mathematical problems that are extremely difficult for classical computers to solve. A sufficiently powerful quantum computer could, in the future, undermine some of these mechanisms. This does not mean the end of cryptography, but rather the need to transition to algorithms that are resistant to new computing models.
Post-quantum cryptography develops methods designed to work on current devices, but that are also resistant to known classes of quantum attacks. The migration involves much more than simply renaming an algorithm; organizations need to know where they use keys and certificates, how long the protected data retains its value, and which systems can be updated.
How can we expand our knowledge of cryptography and cybersecurity?
Cryptography combines theory with practice. Understanding algorithms requires a foundation in mathematics and computer science, but the ability to securely implement libraries, protocols, and key management systems is equally important. After all, an implementation error can compromise even a properly designed method.
Those starting their technical education can develop a foundation in programming, algorithms, computer networks, and security through the “computer science ” program atPJAIT. These are areas that help students understand not only how security measures work, but also the systems and applications in which they are used.
For college graduates interested in the technical protection of infrastructure, there is a postgraduate program in Cybersecurity of Information Technology and Telecommunications Systems. The program combines information protection with the security of networks, systems, and telecommunications environments, as well as practical training in attack and defense methods.
curriculum Cybersecurity—management, systems, and product security—focuses on cybersecurity from the perspectives of technology, risk management, regulation, and the entire lifecycle of a digital product. This perspective is important because the decision to use cryptography should be based primarily on a thorough analysis of threats and the solution’s architecture.
Cryptography as the Foundation of Digital Trust
Cryptography protects modern communications, data, and operations performed in information systems. Symmetric encryption provides efficient protection for large amounts of information, while asymmetric cryptography supports secure key exchange, authentication, and digital signatures. Hash functions, on the other hand, allow for the verification of data integrity and the development of additional security mechanisms.
However, no single algorithm can solve all problems. Effective protection requires the proper selection of methods, secure implementation, key management, and the integration of cryptography with access control, monitoring, and organizational procedures. It is precisely the ability to build such multi-layered systems that makes cryptographic knowledge one of the most important competencies in cybersecurity.
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