The History of Encryption: How Security Has Evolved to Protect Your Business Today

The only way I Encryption has become one of the foundations of modern business security. It protects the information stored on laptops, secures online payments, keeps emails private and prevents criminals from reading data stolen during a cyberattack.

However, encryption is far from a modern invention. For thousands of years, people have looked for ways to disguise information so that only the intended recipient could understand it.

What began with simple substitutions and secret symbols has developed into complex mathematical systems capable of protecting billions of digital interactions every day. Understanding this journey helps explain why encryption is now essential for every business—not only governments, banks and large corporations.

What is encryption?

Encryption is the process of converting readable information, known as plaintext, into an unreadable format called ciphertext.

The encrypted information can only be returned to its original form using the correct key or authorised system. Without that key, the data should be extremely difficult—or practically impossible—to interpret.

Businesses now use encryption to protect:

• Emails and instant messages
• Customer and employee information
• Financial records
• Passwords and authentication details
• Cloud files and backups
• Online transactions
• Laptop, mobile phone and server data
• Connections between offices and remote workers

Although today’s encryption relies on advanced mathematics and computing power, its basic purpose has remained unchanged: prevent unauthorised people from understanding sensitive information.

Ancient encryption and the first secret messages

Some of the earliest examples of encoded writing date back thousands of years. Ancient civilisations occasionally altered symbols or writing styles to conceal information, demonstrate knowledge or restrict access to a message.

One early military encryption method was the Spartan scytale. A strip of material was wrapped around a wooden rod, and the message was written across it. Once removed, the letters appeared scrambled. The recipient needed a rod of the same diameter to read the message correctly.

By modern standards, this was extremely simple. However, it introduced an important principle that remains central to encryption today: both parties needed access to the correct method or key.

The Caesar cipher

One of history’s best-known encryption techniques is the Caesar cipher, named after Julius Caesar, who reportedly used it to protect military communications.

The technique shifted each letter of the alphabet by a fixed number of positions. For example, an “A” might become a “D”, a “B” might become an “E” and so on.

This is known as a substitution cipher because one character is substituted for another.

The Caesar cipher would offer almost no protection today. There are only a limited number of possible shifts, and a computer could test them all almost instantly. Nevertheless, it demonstrated how information could be transformed according to a repeatable rule.

This same general idea—applying a defined process to readable information—is still present in modern encryption, although today’s algorithms are vastly more sophisticated.

Codebreaking begins to develop

As encryption methods became more common, people also developed better ways to break them.

Simple substitution ciphers could be analysed by examining how often particular letters appeared. In English, for example, letters such as “E”, “T” and “A” appear more frequently than many others.

By studying these patterns, codebreakers could begin to identify which encrypted characters represented particular letters. This technique became known as frequency analysis.

This created an ongoing cycle that continues today:

1. A new method is created to protect information.
2. Attackers develop techniques to defeat it.
3. Stronger encryption is introduced.
4. New attacks and countermeasures follow.

Cybersecurity is still shaped by this continuous competition between protection and attack.

More complex ciphers emerge

Over time, encryption systems became more advanced. Rather than replacing each letter in the same way throughout a message, polyalphabetic ciphers used multiple substitution patterns.

One of the most famous examples was the Vigenère cipher, which used a keyword to determine how letters should be shifted. Because the substitution changed throughout the message, traditional frequency analysis became more difficult.

For a time, the Vigenère cipher was considered exceptionally secure. However, weaknesses were eventually discovered, particularly when short or repeated keys were used.

This highlighted another lesson that remains important for businesses today: strong encryption can still be undermined by poor key management.

A sophisticated security system offers limited protection when passwords are weak, keys are reused or authorised access is not properly controlled.

Mechanical encryption and the Enigma machine

Encryption changed dramatically during the twentieth century as mechanical systems became available.

The Enigma machine, used extensively by Nazi Germany during the Second World War, employed rotating wheels to change the substitution pattern each time a key was pressed. This produced an enormous number of possible configurations.

The settings changed regularly, making messages extremely difficult to decipher without knowing the correct configuration.

The work carried out at Bletchley Park, involving mathematicians, linguists, engineers and intelligence specialists including Alan Turing, played an important role in breaking Enigma-encrypted communications.

The effort demonstrated that encryption security depended on more than the machine itself. Operational mistakes, repeated patterns, captured materials and knowledge of how messages were structured all contributed to successful codebreaking.

Modern organisations face similar challenges. Encryption may be technically strong, but human behaviour, configuration errors and poor security procedures can still expose protected information.

The computer age transforms encryption

As computers became increasingly important to governments and businesses, encryption needed to protect information stored and processed electronically.

Manual and mechanical methods were no longer sufficient. Organisations required standardised encryption algorithms that could secure large volumes of digital information quickly and reliably.

One significant development was the Data Encryption Standard, commonly known as DES. It became an important commercial encryption standard and was widely adopted for protecting electronic information.

However, increasing computing power eventually made DES vulnerable to brute-force attacks, in which a system repeatedly attempts different keys until it discovers the correct one.

DES was later replaced by stronger approaches, including the Advanced Encryption Standard, or AES.

AES remains widely used today to protect files, storage devices, wireless networks, applications and cloud services. Depending on its implementation, it can use 128-bit, 192-bit or 256-bit keys.

The size of these keys creates an extraordinarily large number of possible combinations, making properly implemented AES encryption extremely resistant to brute-force attacks with current technology.

Symmetric encryption

Traditional encryption generally relied on a shared secret key. The same key was used to encrypt and decrypt the information.

This is known as symmetric encryption.

Symmetric encryption is fast and efficient, making it suitable for securing large amounts of data. However, it creates an important problem: how can two parties securely exchange the key?

When a business needs to communicate securely with thousands of customers, employees, suppliers or systems, manually sharing secret keys would be impractical and risky.

The development of public-key encryption helped address this challenge.

The arrival of public-key encryption

Public-key encryption, also known as asymmetric encryption, uses two related keys:

• A public key that can be shared
• A private key that must remain confidential

Information encrypted with the public key can only be decrypted with the corresponding private key.

This approach allows secure communication to be established without both parties having previously exchanged the same secret key.

Public-key cryptography also supports digital signatures. A digital signature can help verify that a message or document came from the expected sender and has not been altered.

This technology became critical to the growth of secure online communication and electronic commerce.

Encryption makes online business possible

When customers enter payment details, sign in to an online service or submit information through a secure website, encryption protects the connection between their device and the organisation’s server.

This is commonly provided through Transport Layer Security, or TLS. Secure websites use TLS to create an encrypted connection and authenticate the website through a digital certificate.

This is represented by “https” at the beginning of a website address and the security indicators shown by modern web browsers.

Without encrypted web connections, information could potentially be intercepted while travelling across networks.

Encryption therefore helped make online banking, e-commerce, cloud computing, remote working and digital public services practical.

Encryption moves into everyday business technology

Encryption was once primarily associated with military and government communications. It is now embedded throughout the tools businesses use every day.

Microsoft 365, cloud platforms, business applications, laptops, mobile devices, virtual private networks and modern backup systems all use different forms of encryption.

Common examples include:

Full-disk encryption

Technologies such as BitLocker can encrypt an entire device. If a laptop is lost or stolen, the information stored on it should remain unreadable without the correct credentials or recovery key.

Email encryption

Email encryption can restrict who is able to read or forward a message. It can be particularly valuable when sharing financial, legal, medical or personally identifiable information.

Encrypted cloud storage

Cloud providers commonly encrypt data while it is being transferred and while it is stored. Additional access controls, monitoring and customer-managed encryption keys may also be available.

Virtual private networks

A VPN creates an encrypted connection between a user or location and another network. This can help protect information travelling across untrusted or public connections.

Password protection

Responsible services do not normally store user passwords as readable text. Instead, they use cryptographic hashing and other safeguards designed to prevent the original passwords from being easily recovered.

Encrypted backups

Backup encryption helps prevent criminals from accessing sensitive information if backup files or storage systems are compromised.

Encryption and the rise of remote working

Remote and hybrid working have increased the importance of encryption.

Employees may now access business information from homes, customer sites, hotels and public networks. Data is constantly moving between devices, cloud services, offices and third-party applications.

Encryption can help protect this information, but it must form part of a wider security strategy.

For example, an encrypted laptop may still be compromised when:

• The user’s password is stolen
• The attacker gains access while the device is already unlocked
• Multi-factor authentication is not enabled
• Malware captures information after it has been decrypted
• Sensitive files are shared with the wrong person
• Recovery keys are poorly protected

Encryption is powerful, but it does not replace secure identity management, endpoint protection, monitoring, backups or employee training.

Why encryption matters to your business

Businesses hold more sensitive information than many owners realise. Even a relatively small organisation may process employee records, customer details, supplier information, invoices, bank details, contracts and confidential correspondence.

Encryption can help reduce several important risks.

Protecting stolen devices

When a properly encrypted laptop or phone is lost, the information on it is far less likely to be accessed by an unauthorised person.

Reducing the impact of intercepted data

Encryption helps ensure information cannot be easily read when it is intercepted while travelling between systems.

Supporting compliance

Encryption can help businesses demonstrate that they have taken appropriate steps to protect personal and confidential information. However, it should be implemented alongside access controls, retention policies, monitoring and other security measures.

Building customer confidence

Customers want reassurance that organisations will handle their data responsibly. Appropriate encryption contributes to a professional and trustworthy security posture.

Supporting secure collaboration

Encryption allows teams, clients and suppliers to exchange sensitive information more safely, particularly when combined with controlled sharing and identity verification.

Limiting the damage caused by cybercrime

Encryption cannot stop every breach, but it may prevent stolen files from being immediately readable or useful to an attacker.

The importance of encryption key management

Encryption is only as effective as the protection given to its keys.

If an attacker obtains the correct encryption key, the protected information may become accessible. Equally, if a business loses its own key, it may be unable to recover important data.

Businesses should therefore consider:

• Where encryption keys are stored
• Who is authorised to use them
• How access is monitored
• How recovery keys are protected
• Whether keys are regularly rotated
• What happens when an employee leaves
• How keys are backed up
• Whether third parties can access them

Recovery keys should not simply be stored beside the devices or systems they unlock. Centralised, controlled key management is much safer than relying on individuals to keep important keys or passwords.

The threat from quantum computing

Encryption continues to evolve because technology never stands still.

Quantum computing may eventually be capable of solving certain mathematical problems much faster than traditional computers. This could weaken some of the public-key encryption methods currently used to protect digital communications.

Although large-scale cryptographically relevant quantum computers are not part of normal business operations today, governments, technology companies and standards organisations are already developing and adopting post-quantum encryption approaches.

Businesses do not need to panic, but they should maintain an accurate understanding of:

• Where encryption is being used
• Which systems and algorithms they rely on
• How long sensitive data must remain confidential
• Whether suppliers have plans for future encryption upgrades
• Which legacy systems may be difficult to update

Organisations holding highly sensitive information for many years may need to consider this transition earlier than businesses processing short-lived data.

Encryption must be part of a layered security strategy

One of the biggest mistakes a business can make is assuming that encryption alone makes information secure.

Encryption protects data, but it does not automatically prevent:

• Phishing attacks
• Account takeover
• Malware and ransomware
• Inappropriate permissions
• Insider threats
• Accidental data sharing
• Weak passwords
• Unpatched software
• Poor backup practices
• Social engineering

A strong business security strategy should combine encryption with:

• Multi-factor authentication
• Endpoint detection and response
• Secure backups
• Email filtering
• Patch management
• Access controls
• Security monitoring
• Staff awareness training
• Incident response planning
• Regular security reviews

The objective is to make sure that one failed control does not expose the entire organisation.

Is your business using encryption correctly?

Many businesses already use encryption without fully understanding where it is enabled, who manages it or whether every important device is covered.

A practical review should consider:

1. Are all business laptops and mobile devices encrypted?
2. Are encryption recovery keys stored securely?
3. Are sensitive emails and files shared using appropriate controls?
4. Are backups encrypted both in storage and during transfer?
5. Are remote connections properly secured?
6. Are older systems using outdated encryption protocols?
7. Are cloud applications configured according to the sensitivity of the information they contain?
8. Can the business revoke access quickly when an employee leaves?
9. Are third-party suppliers protecting information to the required standard?
10. Is encryption regularly reviewed as part of the wider cybersecurity strategy?

Finding that encryption is available is not the same as confirming that it has been correctly enabled, configured and monitored.

From secret symbols to modern cybersecurity

The history of encryption shows how security has continually adapted to new threats.

Ancient ciphers protected handwritten military instructions. Mechanical systems secured wartime communications. Mathematical algorithms allowed computers to protect electronic data. Public-key cryptography enabled trusted online commerce, while modern encryption now secures cloud services, mobile devices and remote workforces.

Every stage of this development has reinforced the same principle: sensitive information needs protection wherever it is stored, processed or transmitted.

For modern businesses, encryption is no longer an optional or highly specialised technology. It is a fundamental security control that should be present across devices, communications, cloud platforms and backup systems.

However, effective encryption requires more than switching on a setting. It must be supported by strong identity controls, secure key management, sensible permissions, monitoring and a properly planned cybersecurity strategy.

Hamilton Group can help your organisation review how its information is stored, identify gaps in its existing security controls and implement practical protection across Microsoft 365, endpoints, networks, cloud services and backups.

To discuss how your business can use encryption and wider cybersecurity controls more effectively, contact Hamilton Group on 0330 043 0069 or book an appointment with one of our experts.