Cryptography Explained!!! History, Definition, How it Works & Types


Ever heard of the term, “cryptography”? For some, it sounds a little unfamiliar, and for others, a little complex. Either way, that’s about to change because at the end of this article you’d be able to explain, in detail, the concept of cryptography, how it works, and its types; including public-key cryptography.

Let’s set the ball rolling already.

What is Cryptography?

Cryptography is what gives, the term, “cryptocurrency” its name. It predates our digital age and has evolved over time in the same way as languages have.

Basically, cryptography is the study of safeguarding data by converting it into a format that only its prospective recipients can process and read. It was initially used as hieroglyphics in an Egyptian tomb in the year 1900 BC. The term originates from the Greek terms Kryptos, which means hidden, and Graphein, which means to write.


Julius Caesar invented one of the most renowned applications in 40 BC, which he dubbed Caesar’s cipher. A cipher is a code that tells you how to scramble and then unscramble a message using a secret piece of information. Caesar employed the use of a substitution cipher, in which each letter of the alphabet was substituted for a letter in a different fixed position further up or down the alphabet. For example, if the alphabet was to move five spaces to the right, the letter “A” would become “F,” the letter “B” would become “G,” and so on. And because only his officers knew how to decipher the message, he could pass it along without fear of it being intercepted.

On the other hand, the Vigenere cipher (falsely attributed to diplomat Blaise de Vigenere) was designed by Giovan Battista Bellaso, a 16th-century cryptologist, and is thought to be the first cipher to use an encryption key. The alphabet came in a grid of over 26 rows, with each row changing a letter. The encryption key was written to fit the message’s length. The message was then encrypted letter by letter using the grid. Finally, the sender sent the encrypted message and the secret keyword to the recipient, who had the same grid as the sender.

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Then came computers, which allowed for considerably more advanced cryptography. The purpose, however, remains the same; to convert a legible message (plain text) into something that an accidental reader will be unable to comprehend (ciphertext). This process is what we often call Encryption. It is the process by which individuals transfer or share information across public internet connections. The key. on the flip side, is the knowledge of how to decrypt – or unscramble – the data, and it should only be accessible to those who need it.

How Does Cryptography Work?

There are numerous methods for encrypting data, and the complexity of each method is dependent on the level of data protection in play. However, there are three popular types of cryptographic algorithms;

#1. Symmetric Ecryption

A single key is used in symmetric encryption, often known as secret-key encryption. This means that both the transmitter and the receiver of data have access to the same key, which will help to encrypt and decrypt data.

However, to do this, the secret key must be agreed upon in advance.

While still a good option for encryption, the fact that only one key is responsible for protection implies that delivering it through insecure networks poses some danger. Consider how you would wish to hide your front door key under your doormat to share it with a buddy. Your friend has gained access to your residence. But then, there’s a danger that someone else could find the key and enter without your knowledge.

#2. Asymmetric Encryption

Asymmetric encryption, also known as public-key encryption, employs two keys. This additional layer of security boosts data security right away. In this scenario, each key has only one function. A public key exists that may be shared with anyone, over any network. Anyone can use this key because it contains instructions on how to encrypt data. There is, however, a private key. The information on how to decrypt the message stays in the private key. It is not often shared.

Basically, an algorithm that employs huge prime numbers to construct two unique, mathematically connected keys generates both keys. Anyone with access to the public key can encrypt a message, but only the owner of the private key may decrypt it.

It works in a similar way to a mailbox. Literally, anyone can use the deposit slot to leave a message. However, only the mailbox’s owner has the key to open it and read the messages. The majority of cryptocurrency transactions stand on this foundation.

#3. Hash Functions

Cryptography can also be a tool for securing data using hash functions. However, rather than using keys, it uses algorithms to convert any data into a fixed-length string of characters.

Hash functions are also distinct from other types of encryption in that they only work in one direction, which means you can’t reverse a hash back to its original data.

Hashes are crucial to blockchain administration because they can encrypt enormous amounts of data without jeopardizing the integrity of the original data. Not only can having an ordered manner to organize data improve productivity, but hashes may also act as digital fingerprints for any encrypted data. This can then be used to validate and protect against any illegal changes during network transfer. Any changes to the original data would generate a new hash that no longer matched the original source and hence can not be verified on the blockchain.

Signatures in the Digital Age

Another important aspect of ensuring the security, authenticity, and integrity of data in a message, software, or digital document is the use of a digital signature. They function similarly to physical signatures in that they are a one-of-a-kind way to link your identity to data and thus serve as a means of verifying the information.

Digital signatures, unlike physical signatures, do not use a single character to represent your identity. Instead, they use public-key cryptography. The digital signature is delivered as a code that is then appended to the data using the two mutually authenticating keys. The sender creates the digital signature by encrypting the signature-related data with a private key, and the receiver decrypts the data with the signer’s public key.

This code serves as proof that a message was created by the sender and was not tampered with during transmission, as well as ensuring that the sender cannot deny sending the message.

If the recipient can’t decrypt and read the signed document using the specified public key, there’s a problem with the document or signature, and the document can’t be trusted.

Cryptography and Cryptocurrencies are two terms we often use interchangeably

Cryptocurrencies are popular because of their security and transparency on the blockchain. All of this is made possible by cryptographic mechanisms. That is how most blockchain-based cryptocurrencies keep their security, and it is part of the cryptocurrency’s fundamental essence.

Satoshi Nakamoto, the inventor of Bitcoin, proposed a solution to the double-spend problem, which had long been the Achilles heel of digital currencies, on a cryptography message board in 2009. The double-spend problem occurs when the same unit of cryptocurrency can be spent twice. This had often destroyed trust in it as a means of online payment and rendering it essentially worthless.

Nakamoto proposed using a timestamped and cryptographically secured peer-to-peer distributed ledger. As a result, the blockchain as we know it today was born. Cryptography, like any technology, will evolve to meet the demands for a safe digital world. This is especially true as blockchains and cryptocurrencies become more widely adopted across industries and nations.

Techniques of Cryptography

Cryptography and cryptology, as well as cryptanalysis, are closely linked subjects. Techniques such as microdots, merging words with images, and other methods of concealing information in storage or transit are included. However, in today’s computer-centric world, cryptography is most commonly linked with scrambling plaintext (regular text, also known as cleartext) into ciphertext (a process known as encryption), then back again (known as decryption). Cryptographers are professionals who work in this sector.

The following four goals are addressed by modern cryptography:

  • Confidentiality: the information is incomprehensible to anyone who was not supposed to get it.
  • Integrity: the information cannot be tampered with while in storage or in transit between the sender and the intended recipient without being detected.
  • Non-repudiation: the information’s creator/sender cannot later deny his or her intentions for creating or transmitting the information.
  • Authentication: the sender and receiver can verify each other’s identities as well as the information’s origin and destination.

Cryptosystems are procedures and protocols that meet some or all of the above criteria. Cryptosystems are often thought to refer only to mathematical procedures and computer programs; however, they also include human behavior regulation, such as selecting difficult-to-guess passwords, logging off unused systems, and not discussing sensitive procedures with outsiders.

Types of Cryptography

public key cryptography
Source: Ulam Labs

Although there are many different cryptographic methods in use, they can all be divided into three categories: secret-key cryptography, public-key cryptography, and hash functions. Within the cryptographic landscape, everyone has a certain job to play.

#1. Secret Key Cryptography

Secret key cryptography, also known as symmetric-key cryptography, is commonly used to keep data private. It’s particularly handy for keeping a local hard disk private; because the same user encrypts and decrypts the protected data, distributing the secret key isn’t an issue. Secret key cryptography can also be used to keep messages sent over the internet private; however, to do so properly, you’ll need to employ our next type of cryptography in conjunction with it.

#2. Public Key Cryptography

You don’t want to go into your bank and chat with the teller simply to find out what the private key is for encrypting your electronic contact with the bank – it would defeat the purpose of online banking. In general, the internet requires a mechanism for communicative parties to establish a safe communications channel while only interacting with one another via an intrinsically unsecured network in order to function securely. This is accomplished through the use of public-key cryptography.

Each participant in public-key cryptography, also known as asymmetric-key cryptography, has two keys. One is for the general public and is sent to everyone with whom the party desires to communicate. This is the key for encrypting messages. The other key, on the other hand, is private and not shared with anyone, and it’s required to decrypt those messages. To give an analogy, imagine the public key as a slot on a mailbox that is just wide enough to drop a letter inside. You offer those measurements to anyone you think would want to write you a letter. The private key is used to unlock the mailbox and retrieve the letters.

The key to making the procedure work is that the two keys are mathematically related to each other, making it easy to derive the public key from the private key but not the other way around. The secret key, for example, may be two extremely big prime numbers that you multiply together to generate the public key.

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Public key cryptography necessitates far more complicated and resource-intensive computations than secret key architecture. You don’t have to use it to protect every message you send over the internet. Instead, one party will often encrypt a communication containing yet another cryptographic key using public-key cryptography. After securely crossing the insecure internet, this key will be transformed into a private key, which will encrypt a much longer communications session using secret key encryption.

Public key cryptography aids the cause of confidentiality in this way. However, these public keys are part of a larger collection of services known as PKI or public key infrastructure. PKI enables users to verify that a given public key is linked to a certain person or organization. A communication encrypted with a public key thus establishes authentication and non-repudiation by confirming the sender’s identity.

#3. Hash Functions

Plaintext is converted to a ciphertext and then returned to plaintext in both public and private key cryptography techniques. A hash function, on the other hand, is a one-way encryption algorithm: once you’ve encrypted your plaintext, you’ll never be able to recover it from the ciphertext (referred to as a hash).

Hash functions may appear to be a futile exercise as a result of this. However, the key to its utility is that no two plaintexts will return the same hash for any given hash function. (This isn’t precisely right mathematically, but the chances of it happening with any hash function in use are vanishingly small and can be safely ignored.)

As a result, hashing algorithms are an excellent way to ensure data integrity. A message, for example, can be transmitted with its own hash. You may run the same hashing process on the message text when you receive it; if the hash you get differs from the one that came with it, you know the message was changed in transit.

Password secrecy is also ensured via hashing. Storing passwords in plaintext is a major security no-no since it leaves users vulnerable to account and identity theft in the event of a data breach (which, unfortunately, big players continue to do). If you save a hashed version of a user’s password instead, even if hackers defeat your protections, they won’t be able to decode it and use it elsewhere. When a legitimate user signs in, you may simply hash their password and compare it to the hash you have on file.

What’s the difference between Symmetric and Asymmetric?

The same key is used for encryption and decryption in symmetric cryptography. Both the sender and the recipient must have a common key that they both know. Key distribution is a difficult topic that prompted the development of asymmetric cryptography.

Asymmetric cryptography uses two separate keys for encryption and decryption. In an asymmetric cryptosystem, each user has both a public and a private key. The private key must always be kept confidential, whereas the public key can be freely released.

Only the associated private key may decrypt data encrypted with a public key. As a result, sending a message to John necessitates encrypting it with John’s public key. Only John has his private key, thus he can decrypt the message. Only the accompanying public key may decrypt data encrypted with a private key. Jane might also use her private key to digitally sign a message, and anyone with Jane’s public key could decrypt the signed message and verify that it was Jane who sent it.

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Symmetric is a fast encryption algorithm that is perfect for encrypting huge amounts of data (e.g., an entire disk partition or database). Asymmetric encryption is slower and can only encrypt data fragments smaller than the key size (typically 2048 bits or smaller). As a result, asymmetric cryptography is commonly used to encode symmetric encryption keys, which are subsequently used to encrypt significantly bigger data blocks. Asymmetric cryptography is typically used to encrypt message hashes rather than whole messages for digital signatures.

The generation, exchange, storage, usage, revocation, and replacement of cryptographic keys are all managed by a cryptosystem.

What Problems Does Cryptography Address?

Data confidentiality, integrity, and availability, as well as authenticity and non-repudiation, should all be guaranteed by a secure system. Cryptography, when applied effectively, can assist give these assurances. Both data in transit and data at rest can be kept confidential and secure using cryptography. It can also guard against repudiation by authenticating senders and recipients.

Many endpoints, often multiple clients, and one or more back-end servers are common in software systems. These client/server communications take place via unreliable networks.

It can secure messages that pass via untrustworthy networks. However, it is possible for a hacker to carry out one of two types of assaults on a network. An attacker using passive assaults simply listens on a network segment and tries to read sensitive data as it travels. Passive attacks can be carried out online (in which an attacker reads the information in real-time) or offline (in which an attacker just collects data in real-time and examines it later—possibly after decrypting it). On the other hand, an attacker could also impersonate a client or server, intercepts messages in transit, and view and/or modify the contents before sending them on to their intended destination in an active attack (or dropping them entirely).

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Cryptographic technologies like SSL/TLS provide confidentiality protection that can shield communications from malicious eavesdropping and alteration. Authenticity safeguards ensure that users are communicating with systems in the appropriate manner. Are you, for example, transferring your online banking password to your bank or to a third party?

It can also be used to safeguard data in transit. Data on a detachable disk or in a database can be encrypted to prevent sensitive information from being leaked if the physical medium is lost or stolen. It can also secure data at rest from malicious tampering by providing integrity protection.

What Are the Principles?

The most important thing to remember is that you should never try to create your own cryptosystem. The world’s most intelligent cryptographers (Phil Zimmerman and Ron Rivest, for example) often produce cryptosystems with major security problems. To be certified “safe,” a cryptosystem must be subjected to rigorous testing by the security community. Never rely on obscurity or the fact that attackers may not be aware of your system for security. Remember that your system may also be attacked by malicious insiders and determined attackers.

When it comes to a secure cryptosystem, the only thing that should be kept “hidden” are the keys themselves. Take the necessary precautions to safeguard any keys that your systems rely on. Encryption keys should never be stored in transparent text alongside the data they protect. It’s the same as locking the front door and hiding the key beneath the doormat as we earlier mentioned. It’ll be the first thing an attacker looks for.

Here are three common key-protection systems (in order of least to most secure):

  • Store keys in a filesystem and use strong access control lists to secure them (ACLs). Always remember to follow the principle of least privilege.
  • Using a second key encrypting key, encrypt your data encryption keys (DEKs). Password-based encryption should be used to create the KEK (PBE). A password known by a small number of administrators can be used to bootstrap the cryptosystem by generating a key using an algorithm like bcrypt, scrypt, or PBKDF2. This eliminates the need to keep the key unencrypted in any location.
  • A tamper-resistant hardware appliance called a hardware security module (HSM) can be used to store keys securely.
  • Make sure you’re only using algorithms, key strengths, and operating modes that follow industry best practices. The Advanced Encryption Standard (AES) is the industry standard for symmetric encryption (with keys of 128, 192, or 256 bits). The standard for asymmetric encryption is RSA with elliptical curve cryptography (ECC) with at least 2048-bit keys.
  • Avoid using insecure modes of operation like AES in Electronic Codebook (ECB) mode or RSA without padding.

What Are the Three Types of Cryptography?

The three types of cryptography include;

  • Secret Key Cryptography.
  • Public Key Cryptography.
  • Hash Functions.

What Is Cryptography Used For?

Basically, cryptography is the study of safeguarding data by converting it into a format that only its prospective recipients can process and read. It was initially used as hieroglyphics in an Egyptian tomb in the year 1900 BC. Now, it has become a framework for creating cryptocurrencies.

What Is Cryptography With Example?

Cryptography is the science of converting data into a secure format in order to protect it. An encrypted communication in which letters replace other characters is an example of fundamental cryptography.

What Is Cryptography vs Encryption?

Encryption is the process of encoding a message with an algorithm, whereas cryptography is the study of ideas like encryption and decryption used to guarantee safe communication.

What Are Cryptography Techniques?

Cryptography is a method of safeguarding information and communications by encoding it in a way that only the people who need to know can interpret and process it. As a result, unwanted access to information is prevented. The suffix graphy means “writing” and the word “crypt” means “hidden.”

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