Cracking the Code: A Beginner’s Guide to Understanding Cryptography

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Cracking the Code: A Beginner’s Guide to Understanding Cryptography

Have you ever wondered how your sensitive information is kept safe when you use the internet or mobile devices? That’s where cryptography comes in. In simple terms, cryptography is the practice of securing information so that it can only be accessed by those who are authorized to do so. It is a crucial component of modern technology, enabling secure online transactions, protecting personal data, and keeping sensitive information safe from unauthorized access.

In this article, we will explore the basics of cryptography, including its definition and purpose, the history of Cryptography, the different types of cryptography, and how it is used to protect information.


Cryptography is a method of protecting information from unauthorized access or disclosure when communicating over insecure channels. It involves converting plain text into a secret code, known as ciphertext, using a mathematical algorithm and a secret key. The cipher-text can only be read by the intended recipient, who possesses the same secret key. Cryptography is widely used in various applications, such as email, online banking, messaging, and e-commerce.

Purpose of Cryptography

The primary purpose of cryptography is to protect information from unauthorized access, tampering, or disclosure. In other words, cryptography ensures that only the intended recipient can read the message and that no one else can intercept or alter it.

For example, consider the case of online shopping. When you enter your credit card details on a website, cryptography is used to scramble your sensitive information into a form that can only be understood by the seller’s server. This prevents any eavesdropping or interception of your credit card details by a third party, ensuring the privacy and security of your transaction.

How does Cryptography work?

Cryptography is the practice of securing information by transforming it into an unreadable format, called ciphertext, that can only be deciphered by someone who has the correct key to decrypt it. This is done through a set of algorithms and mathematical formulas that scramble the original message in a way that makes it extremely difficult, if not impossible, for anyone who doesn’t have the key to understand.

Let’s take an example to illustrate how cryptography works. 

Let’s say you want to send a secret message to your friend. You write the message on a piece of paper, but instead of using regular letters, you use a code to scramble the letters. This is called encryption.

To unscramble the message and read it, your friend needs a special key that tells them how to decipher the code. This is called decryption.

You could use a basic cryptography technique called a Caesar cipher. Here’s how it works:

1. Choose a secret key: In the Caesar cipher, the key is a number between 1 and 25 that represents the shift in the alphabet. For example, if you choose the number 3 as your key.

2. Encrypt your message: To encrypt your message, you simply replace each letter in the message with the letter that is three places to the right in the alphabet.

For example, if your message is “Hello”.

To make it secret, you shift each letter in your message three places to the right in the alphabet. So, H becomes K, E becomes H, L becomes O, and so on. Now your secret message is “khoor”.

3. Send the encrypted message: Now you can send the encrypted message to your friend, and if anyone intercepts it, they won’t be able to read it without the key.

4. Decrypt the message: When your friend receives the secret message, they will know the secret number (in this case, 3) and use it to shift the letters three places to the left in the alphabet. So, K becomes H, H becomes E, O becomes L, and so on. Now, your friend can read the original message: “Hello”!

The History of Cryptography

Cryptography has been around for a very long time – since at least 2000 B.C.! The ancient Egyptians used hieroglyphics to create secret messages that only a select few could understand.

In more recent history, Julius Caesar came up with a clever way to keep his messages secret. He replaced each letter in his messages with a letter three positions ahead of it in the Roman alphabet. This meant that even if someone intercepted his message, they wouldn’t be able to read it without knowing the secret code.

Cryptography has always been important for keeping information safe, especially during times of war or in the business world. Governments have even placed restrictions on cryptography to prevent certain groups from accessing sensitive information that could be used against national interests.

However, the internet has allowed the spread of powerful programs and techniques of cryptography to become available to the public. This means that many of the most advanced cryptosystems and ideas are now accessible to everyone, not just a select few.

Types of Cryptography

When it comes to cryptography, there are two main types: 

1. Symmetric key cryptography

2. Asymmetric key cryptography

In symmetric key cryptography, the sender and receiver use the same key for both encryption and decryption of the message. It’s like using the same lock and key for both opening and closing a safe. This method is simple and fast, but the biggest drawback is that the same key must be shared with the recipient beforehand, which can make it vulnerable to interception by third parties.

On the other hand, asymmetric key cryptography uses two different keys – a public key and a private key – for encryption and decryption. The public key is shared with everyone, and anyone can use it to encrypt a message. But only the recipient, who holds the private key, can decrypt the message. It’s like using a lock with a unique key that only the recipient has. This method is more secure than symmetric key cryptography, but it’s slower and more complex to use.

A common example of asymmetric key cryptography is SSL/TLS, which is used to secure online transactions. When you enter your credit card information on a website, the information is encrypted using the website’s public key. The website’s server then uses its private key to decrypt the information and process the transaction securely.

How it secures our information

Cryptography is used to protect information through various techniques such as encryption, decryption, and digital signatures. Encryption is the process of converting plain text into a coded language, called ciphertext, that can only be deciphered with the correct key. Decryption is the opposite process of converting ciphertext back into plain text using the correct key.

Digital signatures, on the other hand, use asymmetric key cryptography to ensure the authenticity of the message. The sender uses their private key to encrypt the message, and the recipient uses the sender’s public key to verify the signature. This ensures that the message was indeed sent by the sender and has not been tampered with in transit.

Cryptography is widely used to protect sensitive information such as passwords, credit card details, and personal data. It is also used to secure communication over the internet, such as online banking, e-commerce, and email services. Without cryptography, sensitive information would be vulnerable to interception and unauthorized access, leading to data breaches and identity theft. 

Cryptography in Online Banking

let’s take the example of online banking. When you log in to your online bank account, you want to be sure that your personal and financial information is protected from any potential hackers. This is where cryptography comes in.

To protect your information, your bank uses encryption to scramble your login credentials and other sensitive data before it is transmitted over the internet. The encryption process uses a combination of algorithms and keys to make the data unreadable to anyone who intercepts it.

For example, when you enter your username and password to log in to your bank account, that information is encrypted before it is sent over the internet to the bank’s server. The server then uses a private key to decrypt the information and verify your identity. Once your identity is confirmed, the server will allow you to access your account information.

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