The Internet: Encryption & Public Keys

Summary

This video explains the fundamentals of encryption, a crucial process for keeping data secure on the open internet. The speaker, Mia Gil-Epner, introduces encryption methods like Caesar's Cipher and highlights the limitations of basic encryption in the face of modern computing power. She then explores how modern encryption techniques, like 256-bit keys and asymmetric encryption using public and private keys, ensure the security of sensitive information online. The video emphasizes the importance of encryption in safeguarding data and the continuous need for advancements as computers become faster.

Takeaways

• 💻 The internet is an open system where private information, like credit card details and passwords, is exchanged.
• 🔒 Encryption is the process of scrambling messages to hide the original text, while decryption reverses this to make the message readable.
• 🔐 Caesar's Cipher, one of the earliest encryption methods, shifts letters in a message based on a key.
• 🛠 A major weakness of Caesar's Cipher is that it can be easily cracked by trying all possible keys (only 26 possibilities in the English alphabet).
• 🔑 More complex encryption methods, like using different shifts for each letter, create billions of possible key solutions.
• 🚀 Modern encryption uses 256-bit keys, which are almost impossible to crack even with supercomputers due to the astronomical number of possibilities.
• 🧮 As computers get faster, the encryption key length must increase to maintain security, but longer keys make cracking exponentially harder.
• 📧 Symmetric encryption uses the same key for both scrambling and unscrambling messages, but it requires sharing the key in private beforehand.
• 📬 Asymmetric encryption uses a public key for encryption and a private key for decryption, allowing secure communication without pre-agreed private keys.
• 🌐 Public key cryptography underpins secure communication on the internet, used in protocols like SSL and TLS, indicated by the 'https' and padlock in browsers.

Q & A

What is encryption, and why is it important in communication?

Encryption is the process of scrambling or changing a message to hide its original text, making it unreadable to unauthorized users. It's important because it ensures the privacy of sensitive data, such as credit card numbers, passwords, and emails, as it's transmitted over the open internet.

How does Caesar's Cipher work?

Caesar's Cipher is an encryption algorithm that substitutes each letter in a message with another letter a fixed number of steps down the alphabet. The key is the number of steps, which must be shared between the sender and receiver to encrypt and decrypt the message.

What is the main vulnerability of Caesar’s Cipher?

The main vulnerability of Caesar’s Cipher is that it can be easily cracked by trying all possible keys. Since there are only 26 letters in the English alphabet, a person could try all 26 possibilities to decrypt the message.

How can encryption be made more secure than Caesar’s Cipher?

Encryption can be made more secure by using a longer, more complex key that shifts each letter of the message by different amounts. For example, using a 10-digit key would result in 10 billion possible key solutions, making it much harder to crack.

Why are modern computers able to break simple encryption methods quickly?

Modern computers can try a large number of possibilities very quickly. For example, they can test billions of keys per second, which allows them to break simple encryption methods like Caesar’s Cipher almost instantly.

What is 256-bit encryption, and why is it considered secure?

256-bit encryption uses a key that is 256 bits long, providing a massive number of possible key combinations. Even with the fastest computers, it would take trillions of years to try every possible key, making this level of encryption extremely secure.

How does the concept of symmetric encryption work?

In symmetric encryption, both the sender and receiver use the same key to encrypt and decrypt a message. This key must be shared privately between them, which can be difficult over public networks like the internet.

What is asymmetric encryption, and how does it differ from symmetric encryption?

Asymmetric encryption uses two keys: a public key that can be shared with anyone to encrypt data and a private key that is kept secret to decrypt the data. This method allows secure communication over public networks without needing to agree on a private key beforehand.

How does public key cryptography ensure secure communication over the internet?

Public key cryptography allows anyone to use a public key to encrypt a message, which can only be decrypted by the owner of the private key. This method is the foundation of secure communication protocols like SSL and TLS, which protect data transmitted over the internet.

What is the significance of the lock symbol or 'https' in a browser’s address bar?

The lock symbol or 'https' in a browser’s address bar indicates that the website is using SSL or TLS protocols, which means that public key encryption is being used to secure the data exchanged between your computer and the website.

Outlines

00:00

🔐 Introduction to Encryption and Data Privacy

Mia Gil-Epner introduces herself as a computer science major working for the Department of Defense. She explains how the internet, despite being an open system, involves the exchange of private data like credit card numbers and passwords. To protect this sensitive information, encryption is used, a process that scrambles the data to hide its original form. Decryption is the reverse process, allowing the message to be readable again.

05:05

📜 The Origins of Encryption: Caesar’s Cipher

The video dives into the history of encryption, focusing on Caesar's Cipher, one of the earliest encryption methods. Named after Julius Caesar, it works by shifting each letter in a message by a set number of positions in the alphabet, a number known only to the sender and receiver, called the key. However, this simple cipher can be easily cracked by testing all possible 26 keys, making it weak by today's standards.

🔢 Strengthening Encryption with Multiple Shifts

A limitation of Caesar’s Cipher is its ease of being cracked by trying every possible key. To improve encryption, the video suggests shifting each letter by a different amount using a longer key. For example, a 10-digit key allows for 10 billion possible combinations, significantly harder to crack. But even with such complexity, modern computers can break this encryption in seconds.

💻 Modern Encryption and 256-bit Security

In the modern digital age, stronger encryption is required due to the computational power available today. The video explains the use of 256-bit encryption, which creates an astronomical number of possible key combinations, making it almost impossible to crack. Even with supercomputers, it would take trillions of years to break such encryption, ensuring data remains secure.

⚖️ Symmetric vs Asymmetric Encryption

The video introduces two types of encryption: symmetric and asymmetric. Symmetric encryption uses the same key for both scrambling and unscrambling the message, which requires the key to be shared in private beforehand. Asymmetric encryption, however, uses two keys: a public key for encrypting data and a private key for decryption. This method allows secure communication over public networks like the internet.

📬 Public Key Cryptography and Internet Security

To further explain asymmetric encryption, the video uses the analogy of a mailbox where anyone can drop in a message, but only the owner has the key to access it. Public key cryptography, which includes protocols like SSL and TLS, is the backbone of secure online communication. Every time you see 'https' or a lock icon in your browser, this system is keeping your data safe during internet transactions.

⚙️ The Future of Encryption and Cybersecurity

As the internet grows and computers become faster, the demand for secure encryption will increase. The video emphasizes that encryption methods will need to evolve to keep up with advancements in computing power, ensuring that sensitive data remains protected. Mia concludes by highlighting her work in this rapidly changing field of encryption and cybersecurity.

Keywords

💡Encryption

Encryption is the process of converting data into a coded form to prevent unauthorized access. In the video, encryption is described as the method used to scramble or change private information so that it can't be read by others. For example, it mentions how we encrypt sensitive data like credit card numbers and passwords when sending it over the internet to keep it secure.

💡Decryption

Decryption is the process of converting encrypted data back into its original form so it can be understood. The video explains decryption as the reversal of encryption, where the scrambled message is unscrambled so that the recipient can read it. Decryption is essential for ensuring that the intended person can read the secret message after it's encrypted.

💡Caesar's Cipher

Caesar's Cipher is an early encryption algorithm named after Julius Caesar, who used it to protect his military commands. It works by shifting each letter of a message by a fixed number of places in the alphabet. The video explains that while this method was useful in ancient times, it is now easily breakable due to the small number of possible keys.

💡Key

A key is a piece of information that determines how a message is encrypted or decrypted. In the video, a key is defined as the number of steps used in Caesar's Cipher to shift letters, which allows the recipient to unlock the scrambled message. It further explains that in modern encryption, the key must be kept secret to maintain security.

💡Symmetric Encryption

Symmetric encryption is a method where the same key is used for both encrypting and decrypting a message. The video explains that this type of encryption requires both the sender and the receiver to share the secret key in advance, which is secure for small-scale communication but not practical for the open internet.

💡Asymmetric Encryption

Asymmetric encryption uses two different keys—a public key for encrypting data and a private key for decrypting it. The video explains how this method allows secure communication over the internet without the need for the sender and receiver to privately share a key beforehand. This concept is the foundation of secure online messaging.

💡Public Key

A public key is part of an asymmetric encryption system that can be freely shared with anyone to encrypt data. In the video, the public key is compared to a deposit key for a mailbox, allowing anyone to send encrypted messages to a recipient. However, only the recipient with the private key can decrypt the message.

💡Private Key

A private key is a secret key in an asymmetric encryption system used to decrypt data that was encrypted with the corresponding public key. The video explains that the private key remains confidential and is only held by the recipient, ensuring that only they can access the message encrypted with the public key.

💡256-bit Encryption

256-bit encryption refers to a highly secure encryption system that uses a 256-bit key, making it practically impossible to crack. The video highlights how even with advanced computers, it would take trillions of years to try all possible combinations of a 256-bit encryption, making it a standard for modern secure communication.

💡SSL/TLS

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that secure communication over the internet. In the video, these protocols are mentioned as the technology behind the secure exchange of data between a user's computer and websites, signified by the padlock icon or 'https' in the browser's address bar.

Highlights

The internet is an open and public system, yet we exchange a lot of private data like credit card numbers and passwords.

Encryption is the process of scrambling a message to hide the original text, and decryption is the process of unscrambling it to make it readable.

One of the first well-known methods of encryption was Caesar’s Cipher, named after Julius Caesar, which substituted letters in a message by shifting them a certain number of steps down the alphabet.

Caesar’s Cipher is easily cracked since there are only 26 possible keys in the English alphabet, making it relatively easy to decrypt a message by trying all possibilities.

A more secure method than Caesar’s Cipher involves using a longer key, which shifts each letter by a different amount. This greatly increases the number of possible key solutions.

While humans would struggle to guess a 10-digit key, a modern computer can attempt all possibilities in just a few seconds.

To secure communications in a modern world where attackers use computers, we now use 256-bit keys, which are nearly impossible to crack even with supercomputers.

Trying to break a 256-bit encryption would take trillions of years, even with a vast number of supercomputers.

Encryption technology must constantly evolve as computers get faster, necessitating longer key lengths to ensure security.

Symmetric encryption, like Caesar’s Cipher, requires the sender and receiver to share the same secret key in private.

Public key cryptography is used on the open internet, involving both a public key to encrypt data and a private key to decrypt it.

In public key cryptography, anyone can send a message using the public key, but only the receiver with the private key can decrypt it.

Public key encryption is the foundation of internet security protocols such as SSL and TLS, which protect web browsing.

You can see public key encryption in action on secure websites, indicated by a padlock or 'https' in the browser's address bar.

As technology advances, the need for better encryption methods will increase to keep data secure on the internet.

Transcripts

[Music] Hi, my name is Mia Gil-Epner. I’m  

majoring in computer science at UC Berkeley,  and I work for the Department of Defense,  

where I try to keep information safe. The internet is an open and public system.  

We all send and receive information  over shared wires and connections.  

But even though it’s an open system we  still exchange a lot of private data,  

things like credit card numbers, bank  information, passwords, and emails.  

So how is all this private stuff kept secret? Data  of any kind can be kept secret through a process  

known as encryption, the scrambling or changing  of the message to hide the original text.  

Now decryption is the process of unscrambling  that message to make it readable.  

This is a simple idea, and people have been doing  it for centuries. One of the first well-known  

methods of encryption was Caesar’s Cipher,  named after Julius Caesar, a Roman general  

who encrypted his military commands to make sure  that if a message was intercepted by enemies,  

they wouldn’t be able to read it. Caesar’s Cipher is an algorithm that substitutes  

each letter in the original message with a letter  a certain number of steps down the alphabet.  

If the number is something only the sender and  receiver know, then it’s called the key. It  

allows the reader to unlock the secret message. For example, if your original message is “hello,”  

then using the Caesar’s Cipher algorithm with a  key of 5, the encrypted message would be this.  

To decrypt the message, the recipient would  simply use the key to reverse the process.  

But there’s a big problem with Caesar’s Cipher.  Anybody can easily break or crack the encrypted  

message by trying every possible key. In the  English alphabet, there are only 26 letters,  

which means you’d only need to try at  most 26 keys to decrypt the message.  

Now trying 26 possible keys isn’t very  hard. It would take at most an hour to do.  

So let’s make it harder. Instead of shifting every letter  

by the same amount, let’s shift each letter by a  different amount. In this example, a 10-digit key  

shows how many positions each successive letter  will be changed to encrypt a longer message.  

Guessing this key would be really  hard. Using 10-digit encryption,  

there could be 10 billion possible key solutions.  

Obviously, that’s more than any human could  ever solve. It would take many centuries.  

But an average computer today would take just a  few seconds to try all 10 billion possibilities.  

So in a modern world where the bad guys are  armed with computers instead of pencils,  

how can you encrypt messages so securely  that they’re too hard to crack? Now too hard  

means that there are too many possibilities  to compute in a reasonable amount of time.  

Today’s secure communications are encrypted  

using 256-bit keys. That means a bad guy’s  computer that intercepts your message would  

need to try this many possible options until they  discover the key and crack the message. [Music]  

Even if you had a hundred thousand supercomputers  and each of them was able to try a million billion  

keys every second, it would take trillions of  trillions of trillions of years to try every  

option, just to crack a single message  protected with 256-bit encryption.  

Of course, computer chips get twice as fast and  half the size every year or so. If that pace of  

exponential progress continues, today’s impossible  problems will be solvable just a few hundred years  

in the future, and 256 bits won’t  be enough to be safe. In fact,  

we’ve already had to increase the standard key  length to keep up with the speed of computers.  

The good news is, using a longer key doesn’t  make encrypting messages much harder but it  

exponentially increases the number of guesses  that it would take to crack a cipher.  

When the sender and the receiver share the  same key to scramble and unscramble a message,  

it’s called symmetric encryption. With  symmetric encryption, like Caesar’s Cipher,  

the secret key has to be agreed on ahead  of time by two people in private.  

That’s great for people, but the internet  is open and public so it’s impossible  

for two computers to “meet” in private to agree  on a secret key. Instead, computers use asymmetric  

keys: a public key that can be exchanged with  anybody and a private key that is not shared.  

The public key is used to encrypt data and  anybody can use it to create a secret message,  

but the secret can only be decrypted by a  computer with access to the private key.  

How this works is with some math that we won’t get  into right now. Think of it this way. Imagine that  

you have a personal mailbox where anybody can  deposit mail, but they need a key to do it.  

Now you can make many copies of the deposit key  and send one to your friend or even just make it  

publicly available. Your friend or even a stranger  can use the public key to access your deposit slot  

and drop a message in, but only you can open  the mailbox with your private key to access all  

of the secret messages you’ve received. And you can send a secure message back to  

your friend by using the public deposit  key to their mailbox. This way people  

can exchange secure messages without  ever needing to agree on a private key.  

Public key cryptography is the foundation of all  secure messaging on the open internet, including  

the security protocols known as SSL and TLS,  which protect us when we’re browsing the web.  

Your computer uses this today  anytime you see the little lock  

or the letters https in your browser’s  address bar. This means your computer  

is using public key encryption to exchange  data securely with the website you’re on.  

As more and more people get on the internet,  more and more private data will be transmitted  

and the need to secure that data  will be even more important.  

And as computers become faster and faster, we’ll  have to develop new ways to make encryption too  

hard for computers to break. This is what I do  with my work and it’s always changing. [Music]