WEBVTT

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In this lesson,

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we will learn about Asymmetric Cryptography.

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Asymmetric cryptography,

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also known as public-key cryptography,

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uses a pair of keys,

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one public and one private,

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to encrypt and decrypt data.

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In application, one key is used for encryption,

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and the other is used for decryption.

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The same public

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or private key cannot be used for both encryption

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and decryption.

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Let's learn more about asymmetric cryptography

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and code signing.

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First, we have asymmetric cryptography.

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Asymmetric cryptography uses two separate keys,

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a public key for encryption

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and a private key for decryption.

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This key pair approach enhances security by ensuring

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that even if one key,

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for example, the public key, is widely shared,

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the data remains secure

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because the private key is the only key

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that can decrypt the information.

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Asymmetric encryption is particularly useful

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for secure communication, digital signatures,

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and the key exchange process,

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making it fundamental in modern security protocols.

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Common asymmetric algorithms include:

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RSA, DSA, Diffie-Hellman, ElGamal,

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and Elliptic Curve Cryptography.

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The RSA algorithm,

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named after its inventors,

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Rivest, Shamir, and Adleman,

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relies on the mathematical difficulty

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of factoring large prime numbers,

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making it highly secure for encrypting data

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and for creating digital signatures.

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RSA is commonly used in secure web communications,

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such as Secure Socket Layer/Transport Layer Security,

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or SSL/TLS protocols,

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and in various applications

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requiring secure data transmission.

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The digital signature algorithm, or DSA,

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is an asymmetric encryption method designed specifically

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for creating digital signatures.

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Unlike RSA, DSA focuses on authentication

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and integrity of data,

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rather than the encryption itself.

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DSA uses mathematical functions to verify

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that data has not been altered,

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and that it originates from a legitimate sender,

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providing an important layer of trust

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in digital communications.

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Diffie-Hellman, or DH, is primarily used

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for secure key exchange rather than direct data encryption.

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Diffie-Hellman allows two parties

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to independently derive the same shared secret key

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over an unsecured communication.

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This derived shared secret key can be used

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for symmetric encryption.

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So Diffie-Hellman is essential

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for securely setting up encrypted sessions

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between two parties who have never met before,

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such as in VPN connections.

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El Gamal is an asymmetric encryption algorithm

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that builds upon the Diffie-Hellman key exchange method.

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It is used for encrypting data

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and creating digital signatures,

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offering strong security due to its reliance

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on complex mathematical problems.

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However, ElGamal is generally slower

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and requires larger key sizes compared

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to other asymmetric algorithms,

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which can limit its practical applications.

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Elliptic Curve Cryptography, or ECC,

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is a modern asymmetric algorithm known

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for its strong security with relatively small key sizes.

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ECC provides similar security to RSA,

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but with much shorter keys,

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which reduces computational overhead

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and makes it highly efficient.

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This makes ECC particularly useful for mobile devices,

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IoT devices,

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and other environments where processing power

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and bandwidth are limited.

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Overall, asymmetric encryption

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offers a significant advantage over symmetric encryption

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because it does not require sharing a secret key

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between parties,

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reducing the risk of the key being intercepted.

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However, asymmetric encryption

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does have several challenges.

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These challenges are that asymmetric encryption

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requires significant computational power,

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making it slower

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and less efficient than symmetric encryption,

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especially on devices with limited resources.

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The slower speed

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and increased computational power needs

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make it suitable only for small data,

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like digital signatures, rather than large files.

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In addition, the security of the private key

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is critical in asymmetric encryption

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because if the private key is compromised,

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the entire encryption system is vulnerable.

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Despite these limitations,

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asymmetric encryption is excellent

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for securely sharing symmetric keys,

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which are then used for bulk encryption.

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This approach combines the strengths

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of both encryption types,

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the security of asymmetric encryption for key exchange

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and the efficiency of symmetric encryption for encrypting

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and decrypting large amounts of data.

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For example, in a secure communication session,

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the sender uses the recipient's public key

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to encrypt a symmetric key

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that the sender has created for the session.

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Once the symmetric key is securely delivered

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to the recipient,

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both parties can use that symmetric key

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to encrypt and decrypt data efficiently.

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This method ensures

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that if someone intercepts the key exchange,

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they cannot access the symmetric key without having access

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to the recipient's private key, which they don't have.

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This maintains the confidentiality

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and integrity of the communication.

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This process is the basis

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of the SSL/TLS key exchange process.

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Second, we have code signing.

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Code signing is an important application

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of asymmetric cryptography

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that helps ensure the authenticity

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and integrity of software.

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In code signing,

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a software developer

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or organization uses its private key

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to create a digital signature for its code.

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This digital signature acts like a seal of approval,

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showing that the code comes from a trusted source

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and has not been altered since it was signed.

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When a user downloads the software signed

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by the developer's private key,

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their computer uses the developer's public key

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to verify the signature.

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If the signature verifies,

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the software is confirmed as genuine,

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and a user knows they can trust

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that it has not been tampered with.

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So think of code signing like a wax seal on a letter

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from a trusted sender.

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Just as that wax seal shows that the letter is genuine

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and unopened,

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a digital signature shows that code is authentic

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and safe to use.

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Without code signing, users would have no way

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of knowing whether the software they are downloading

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had been altered by an attacker

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to contain some malicious code.

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In this way,

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code signing protects both the developer's reputation

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and the user's security

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by ensuring that only legitimate, unaltered software

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is installed on a device.

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So the code signing process is essential

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for maintaining trust in software distribution,

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especially where downloads happen frequently.

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So remember, asymmetric cryptography,

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also known as public-key cryptography,

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uses a pair of keys,

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one public and one private,

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where one key encrypts the data

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and the other key decrypts it.

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The use of a key pair provides secure communication

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without needing to share secret keys directly.

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However, asymmetric encryption is computationally intensive,

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limited in the size of data that it can handle,

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and relies on keeping the private key private,

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as compromising the private key

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can jeopardize the entire system.

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But even with these limitations,

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asymmetric encryption excels as a method of encrypting

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and exchanging a symmetric key,

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which can then be used for bulk session encryption.

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So asymmetric cryptography is widely used

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in secure communications, digital signatures,

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and key exchanges.

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Common asymmetric encryption algorithms include:

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RSA, DSA, Diffie-Hellman,

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Elliptic Curve Cryptography, and ElGamal.