WEBVTT

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In this lesson,

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we will learn about symmetric cryptography.

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Symmetric cryptography is a type of encryption

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where the same key is used for both encrypting

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and decrypting data.

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Symmetric cryptography concepts include techniques

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such as one-time pad and Lightweight Cryptography.

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Symmetric cryptography is widely used

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for its efficiency in securing data quickly and in bulk.

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Usually, it uses algorithms

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such as the Advanced Encryption Standard (AES).

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Techniques, such as the One-time Pad,

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may offer theoretically unbreakable encryption.

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Lightweight Cryptography, on the other hand, is designed

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for environments with limited power

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and cryptographic processing resources, such as IoT

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or Internet of Things devices.

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Let's learn more about Symmetric Cryptography, Pne-time Pad,

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and Lightweight Cryptography.

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First, we have Symmetric Cryptography.

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Symmetric cryptography is an encryption method

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that uses the same key for both encrypting

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and decrypting data.

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The core advantage of symmetric cryptography is its ability

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to handle bulk encryption efficiently, making it suitable

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for secure file storage and network communications.

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Common symmetric algorithms include

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AES, DES, 3DES, Blowfish, Twofish, RC4, and ChaCha20.

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The Advanced Encryption Standard, or AES,

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is popular for its strong security and fast processing.

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Also, it can function as both a block cipher

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and a stream cipher.

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The Data Encryption Standard, or DES,

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is an older encryption algorithm with a 56-bit key.

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DES is now considered insecure due to its vulnerability

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to brute force attacks.

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DES's enhanced version, Triple DES, or 3DES,

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applies the DES encryption algorithms

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three times to provide added security,

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but it's a little bit slower.

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Next, Blowfish is known for its speed

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and adaptability with variable key lengths,

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but Blowfish has been largely replaced

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by its successor, Twofish, which offers enhanced security

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and performance with up to 256-bit key lengths.

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Finally, Rivest Cipher 4, or RC4, is a fast stream cipher,

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but it's now outdated due to security flaws,

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with ChaCha20 providing a secure

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and efficient alternative to RC4.

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ChaCha20 is widely used in internet protocols

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for its robust encryption strength.

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Second, we have One-time Pad.

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The One-time Pad is considered one of the strongest forms

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of symmetric encryption because it can provide

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perfect forward secrecy when used correctly.

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The core idea behind the one-time pad

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is to use a completely random key

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that is the exact same length

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as the message being encrypted.

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Each bit of the message is combined

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with the corresponding bit of the key,

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using a simple operation, like Exclusive-OR, or XOR,

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which results in a completely random cipher text.

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Because the key is as long as the message

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and is truly random, there are no patterns

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that can be exploited,

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making the encrypted message theoretically unbreakable.

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The key to one-time pad security

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is that the random key must never be reused.

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If the same key is used more than once,

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patterns could emerge that would allow someone

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to decrypt the message.

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Additionally, the randomness of the key must be perfect.

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Any predictable or repeated patterns in the key

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would weaken the encryption.

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So the major challenge with one-time pads

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is then securely sharing the key between the sender

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and receiver, especially since the key must be as long

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as the message and only used once.

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This makes distributing keys securely

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and keeping them secret, a significant logistical problem.

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This requirement makes one-time pads impractical

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for everyday use, limiting them

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to extremely sensitive communications, such as diplomatic

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or military messages where maximum security is required.

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Third and last, we have Lightweight Cryptography.

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Lightweight Cryptography is specifically designed

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for environments with limited computational resources,

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such as Internet of Things or IOT devices, smart sensors,

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and embedded systems.

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Unlike traditional cryptographic algorithms like AES,

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which are highly secure,

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but can be computationally intensive,

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Lightweight Cryptography is optimized to provide security

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with minimal resource consumption.

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This is achieved by using simpler

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and smaller operations, reducing the algorithm's complexity,

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while still maintaining an adequate level of security.

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So, Lightweight Cryptography typically uses smaller keys,

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reduced rounds of encryption,

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and simpler mathematical operations

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to keep computational demands low.

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For instance, instead of the complex substitution

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and permutation operations used in AES,

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lightweight cryptographic algorithms might use

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a basic bit manipulation techniques that require

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less processing power and memory.

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Additionally, these algorithms often have

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shorter block sizes, which means they handle smaller chunks

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of data at a time, further reducing the strain

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on the device's processor.

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While Lightweight Cryptography may not provide

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the same level of security as more robust algorithms,

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it offers a practical solution that protects data,

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while allowing low-power devices

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to operate effectively and securely.

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So remember, symmetric cryptography uses the same key

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for both encryption and decryption, making it efficient

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for securing data quickly and in bulk.

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Common symmetric algorithms include

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the Advanced Encryption Standard, or AES,

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the Data Encryption Standard, or DES, Triple DES, Blowfish,

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Twofish, Rivest Cipher 4, or RC4,

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and ChaCha20, each with varying levels

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of security and performance.

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Next, the one-time pad

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is a unique symmetric encryption method that uses

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a random key as long as the message itself,

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offering a theoretically unbreakable encryption,

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as long as the key is never reused and is truly random.

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However, the challenges of managing

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and securely sharing one-time pad keys make it impractical

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for everyday use.

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Last, Lightweight Cryptography is designed for devices

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with limited computational power, such as Internet of Things

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or IOT devices, balancing security

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with minimal resource consumption

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to protect data without overwhelming the device.