Cryptography: From Ancient Ciphers to Blockchain. The Complete Guide to Information Security in the Digital Age

What Is Cryptography in Simple Terms

The Essence and Significance of Cryptography

Cryptography is not just about encryption; it is the science dedicated to ensuring confidentiality, data integrity, authentication, and non-repudiation.

Cryptography (from Ancient Greek κρυπτός meaning "hidden" and γράφω meaning "to write") is the science of securing information by transforming it.

Core objectives of cryptography:

• Confidentiality: Ensuring that only authorized parties can access information.
• Data Integrity: Guaranteeing that information is not altered during transmission or storage.
• Authentication: Verifying the authenticity of a data source or user.
• Non-repudiation: Ensuring the sender cannot later deny sending a message or transaction.

Where and Why Cryptography Is Used

Cryptography is embedded in our daily lives:

• Secure Websites (HTTPS): Protects data exchanged between users and servers.
• Messengers: Provides end-to-end encryption for messages.
• Email: Enables encryption and digital signatures via PGP or S/MIME.
• Wireless Networks: Secures connections with WPA2/WPA3 protocols.
• Bank Cards: Utilizes cryptographic algorithms in EMV chips.
• Online Banking and Payments: Employs multi-layered cryptographic protection.
• Digital Signatures: Confirms document authenticity.
• Cryptocurrencies: Blockchain leverages cryptographic hash functions and digital signatures.
• Data Protection: Encrypts hard drives, databases, and archives.
• VPN (Virtual Private Network): Encrypts internet traffic.

Cryptography vs. Encryption: What’s the Difference?

• Encryption: The process of converting readable data into an unreadable format using a specialized algorithm and key.
• Cryptography: A broader scientific discipline covering the development and analysis of algorithms, cryptanalysis, protocols, key management, hash functions, and digital signatures.

A Brief History of Cryptography

From Antiquity to the Present: A Short Overview

Ancient World: The earliest known encrypted messages date to Ancient Egypt (circa 1900 BCE) with atypical hieroglyphs. Ancient Sparta (5th century BCE) used the scytale, a rod of specific diameter.

Classical and Medieval Eras: The famous Caesar cipher (1st century BCE) used a simple letter shift. Arab scholars like Al-Kindi (9th century) developed frequency analysis. The Vigenère cipher (16th century) gained traction in Europe.

Modern Era and World War I: Cracking the Zimmermann Telegram was a key factor in the US entering the war.

World War II: The German Enigma machine and its decryption by the Allies (with Alan Turing) proved highly influential.

The Computer Age: In 1949, Claude Shannon published "Communication Theory of Secrecy Systems." The 1970s saw the creation of the DES (Data Encryption Standard). In 1976, Whitfield Diffie and Martin Hellman introduced public-key cryptography. The RSA (Rivest, Shamir, Adleman) algorithm followed.

Legendary Ciphers from History

• Scytale: An example of a transposition cipher.
• Caesar Cipher: A simple shift substitution cipher.
• Vigenère Cipher: A polyalphabetic cipher using a keyword.
• Enigma Machine: An electromechanical device with rotors.

The Shift to Digital Cryptography

The main distinction between digital and classical cryptography lies in the use of mathematics and computational power.

Key milestones in this transition:

• Formalization: Shannon’s research provided a rigorous mathematical foundation for cryptography.
• Standardization: The introduction of standards facilitated compatibility and broad adoption.
• Asymmetric Cryptography: Public-key concepts solved the secure key distribution problem.
• Increased Computing Power: Enabled more complex algorithms.

Cryptographic Methods and Algorithms

Symmetric and Asymmetric Cryptography

Symmetric Cryptography (Secret-Key Cryptography):

• Uses the same secret key for both encryption and decryption
• Offers high processing speed
• Presents challenges in secure key distribution

Asymmetric Cryptography (Public-Key Cryptography):

• Relies on a mathematically linked public–private key pair
• Solves the key distribution problem
• Enables digital signatures
• Is slower than symmetric cryptography

Algorithm Examples:

Symmetric: DES, 3DES, AES, Blowfish, Twofish, GOST 28147-89, GOST R 34.12-2015

Asymmetric: RSA, ECC (Elliptic Curve Cryptography), Diffie-Hellman, ElGamal, GOST R 34.10-2012

How do they work together? A hybrid approach is common: asymmetric cryptography securely exchanges a secret key, which is then used for bulk data encryption with a symmetric algorithm.

Cryptographic Hash Functions

These mathematical functions transform input data of any length into a fixed-length output string.

Key properties:

• One-wayness: Practically impossible to reconstruct original data from the hash.
• Determinism: Identical input always yields the same hash.
• Collision resistance: Nearly impossible to find two different inputs producing the same hash.
• Avalanche effect: Even a minor input change drastically alters the hash.

Applications:

• Data integrity verification
• Password storage
• Digital signatures
• Blockchain technology

Algorithm examples: MD5, SHA-1, SHA-2 (SHA-256, SHA-512), SHA-3, GOST R 34.11-2012

Quantum Cryptography and Its Prospects

The rise of powerful quantum computers poses a major threat to most current asymmetric algorithms.

Two main development paths:

Post-quantum Cryptography (PQC): The creation of new cryptographic algorithms that resist both classical and quantum attacks, based on alternative complex mathematical problems.

Quantum Cryptography: Secures information using quantum mechanics principles. Quantum Key Distribution (QKD) enables two parties to create a shared secret key, and any interception attempt is instantly detected.

Cryptography and Steganography

• Cryptography: Conceals message content, making it unreadable without the key.
• Steganography: Hides the very existence of a secret message by embedding it in another object (image, audio, video, or text).

Using cryptography and steganography together provides dual-layer protection.

Modern Cryptography Applications

Cryptography in the Internet and Messaging

TLS/SSL (Transport Layer Security / Secure Sockets Layer)

The backbone of secure internet (HTTPS):

1. Authenticates servers
2. Establishes secure channels via key exchange
3. Encrypts all traffic between browsers and servers

End-to-End Encryption (E2EE)

Used in secure messengers (Signal, WhatsApp, Threema). Messages are encrypted on the sender’s device and decrypted only by the recipient’s device.

DNS over HTTPS (DoH) / DNS over TLS (DoT)

Encrypts DNS queries to protect browsing activities.

Secure Email (PGP, S/MIME)

Enables email encryption and digital signatures for authentication.

Digital Signatures and Banking Security

Electronic (Digital) Signature (ES/DS)

A cryptographic mechanism validating the authorship and integrity of electronic documents. The document is hashed and the hash is then encrypted with the sender’s private key.

Applications: Legally significant document management, financial reporting, electronic trading, transaction confirmation.

Banking Security:

• Online Banking: Session protection via TLS/SSL, database encryption
• Bank Cards (EMV): Cryptographic keys and authentication operations
• Payment Systems: Advanced cryptographic authorization protocols
• ATMs: Communication encryption and PIN protection
• Transaction Security: Robust protection through cryptographic techniques

Cryptography in Business and Government Organizations

• Corporate Data Protection: Encryption of confidential databases, documents, and archives
• Secure Communications: VPN, encrypted corporate email and messaging
• Secure Document Management: Electronic document management with digital signatures
• Classified Communications: Use of certified cryptographic solutions for state secrets
• Access Management Systems: Cryptographic authentication and authorization

Cryptography in Russian Corporate Systems (1C)

In Russia, the widely-used "1C:Enterprise" platform is integrated with cryptographic information protection tools (CIPT).

Required for:

• Electronic Reporting: Filing with the Federal Tax Service, Pension Fund, Social Insurance Fund using qualified digital signatures
• Electronic Document Management (EDM): Legal document exchange with partners
• Public Procurement Participation: Activity on electronic trading platforms (ETP)
• Data Protection: Encrypting databases or specific records

Cryptography Worldwide

Russia: Achievements and Cryptographic Services

Historical Context: Soviet mathematicians made major contributions to coding theory and cryptography.

State Standards (GOST):

• GOST R 34.12-2015: Symmetric block cipher standard (Kuznyechik, Magma)
• GOST R 34.10-2012: Digital signature algorithm standard
• GOST R 34.11-2012: Cryptographic hash algorithm "Streebog" standard

Regulatory Authorities:

• FSB of Russia: Licenses cryptographic development, production, and distribution; approves standards
• FSTEC of Russia: Oversees technical information security

United States

• NIST: Key role in standardization (DES, AES, SHA)
• NSA: Develops and analyzes cryptography
• Strong academic and private sector

Europe

• ENISA: EU cybersecurity agency
• GDPR: Mandates technical measures for personal data protection
• National centers in Germany, France, UK, and others

China

• Proprietary Standards: SM2, SM3, SM4
• State-Controlled Cryptography
• Active Quantum Technology Research

International Cryptography Standards

• ISO/IEC: Cryptography standards (ISO/IEC 18033, 9797, 11770)
• IETF: Internet standards (TLS, IPsec, PGP)
• IEEE: Network technology standards (Wi-Fi)

Cryptography as a Career

In-Demand Roles and Skills

Cryptographer (Researcher): Develops new cryptographic algorithms and protocols; requires advanced mathematics expertise.

Cryptoanalyst: Specializes in analyzing and breaking ciphers; works in both defense and intelligence sectors.

Information Security Engineer: Uses cryptographic tools to secure systems and data.

Secure Software Developer: Effectively applies cryptographic libraries in secure application development.

Pentester: Identifies vulnerabilities, including cryptographic misconfigurations.

Key Skills

• Solid mathematical foundation
• Understanding of cryptographic algorithms and protocols
• Programming skills (Python, C++, Java)
• Network technology and protocol knowledge
• Operating systems understanding
• Analytical thinking
• Attention to detail
• Ongoing self-education

Where to Learn Cryptography

• Universities: MIT, Stanford, ETH Zurich, EPFL, Technion, and more
• Online Platforms: Coursera, edX, Udacity
• Student Recommendations: Explore the history of cryptography, solve practical problems, read popular science, study mathematics, and write simple programs

Careers and Professional Growth

Sectors: IT, fintech, telecom, government, defense, consulting, large enterprises

Career Path: Progress from junior to senior specialist, security architect, consultant, or researcher

Demand: High and rising due to growing cyber threats

Salaries: Generally above average for the IT sector

Conclusion

Cryptography is a core technology that underpins trust and security in our digital world. Its impact spans from protecting personal communications and financial transactions to enabling government functions and powering advanced technologies like blockchain.

Understanding cryptography basics is increasingly vital—not just for cybersecurity professionals, but for anyone who wants to proactively safeguard their data online. The field keeps evolving, with new challenges (quantum computing) and new solutions (post-quantum algorithms, QKD) continually emerging.

FAQ

What is cryptography, and what is its role in modern information security?

Cryptography is the science of protecting information via encryption. It ensures data confidentiality, integrity, and authentication, securing communications and digital assets from unauthorized access in blockchain and Web3 environments.

How do ancient ciphers (like the Caesar cipher) differ from modern encryption algorithms?

Ancient ciphers such as the Caesar cipher use simple letter substitutions, while modern algorithms employ complex mathematics. Modern encryption includes both symmetric and asymmetric approaches, providing resistance to cryptanalysis that ancient methods cannot achieve.

Symmetric vs. asymmetric encryption: what are they, and what are their pros and cons?

Symmetric encryption uses a single key for encryption and decryption; it is fast and straightforward but poses challenges for secure key management. Asymmetric encryption uses a public–private key pair, offers greater security but is slower. Symmetric methods are ideal for high-speed data transfer, while asymmetric methods are best for secure key exchange and digital signatures.

How does blockchain use cryptography to secure data and verify transactions?

Blockchain applies asymmetric encryption and digital signatures for data security. The private key signs transactions, while the public key verifies signatures. Hashing (SHA-256) produces unique block fingerprints, preventing forgery—any data change alters the hash, exposing tampering. This ensures network operations are immutable, authentic, and secure.

How can you protect personal data in daily life? What practical encryption tools and best practices should you use?

Use applications with end-to-end encryption, enable full-disk encryption, regularly update passwords, activate two-factor authentication, and avoid public Wi-Fi for sensitive activities.

Will quantum computing threaten existing cryptography and blockchain security?

Yes, quantum computing poses a real threat. It could break current RSA and ECC algorithms that secure blockchain. However, the industry is already developing post-quantum cryptographic solutions to counter these future risks.