Symmetric & Asymmetric Encryption

• What is the purpose of encryption?

  To encode a message so it can be read only by the sender and the intended recipient
• What was one of the first forms of encryption mentioned?

  The Caesar cipher
• How does the Caesar cipher work?

  It replaces each letter of the alphabet with another letter a fixed distance away
• What is the term used for the number of places the alphabet has been shifted in the Caesar cipher?

  The key
• What is a major weakness of symmetric encryption?

  The key can be intercepted or duplicated
• How many keys are used in symmetric encryption?

  A single key is used for both encryption and decryption
• What is the main advantage of asymmetric encryption over symmetric encryption?

  It uses two different keys, making it more secure
• What are the two keys in asymmetric encryption called?

  Public key and private key
• What can the public key be used for?

  It can be shared publicly to encrypt messages
• Why should the private key never be shared?

  Because it is used to decrypt messages and must remain confidential
• How does the public-private key method enhance security in communication?

  It allows secure message exchange without sharing the private key
• What happens when Jane uses my public key to encrypt a message?

  Only I can decrypt it using my private key
• What does encrypting a message with my private key signify?

  It confirms the message's authenticity as it can only be decrypted with my public key
• What is a combined encryption key in asymmetric encryption?

  It is created using one person's private key and another person's public key
• What are the four assurances provided by the public-private key system?

  1. Only the intended recipient can read the message
  2. The message is authentic
  3. The message hasn't been modified
  4. The sender's private key remains secure
• What is an encryption key?

  A sequence of alphanumeric characters used for encryption
• What is a popular standard for encryption keys mentioned in the video?

  The 256-bit encryption key
• How many possible combinations are there for a 256-bit encryption key?

  There are $2^{256}$ possible combinations
• How long would it take to crack a 256-bit encryption key using brute force?

  It would take billions of billions of years
• What analogy is often used regarding the time to crack a 256-bit encryption key?

  It would take longer than the current age of the universe
• What are the key features of symmetric encryption?

  • Uses a single key for both encryption and decryption
  • Both parties must know and keep the key secret
  • The same key can be reused or a unique key can be generated each time
  • Vulnerable to key interception or duplication
• What are the key features of asymmetric encryption?

  • Uses two different keys: a public key and a private key
  • The public key can be shared openly
  • The private key must remain confidential
  • Provides enhanced security and authenticity
• What are the steps involved in using public-private key encryption?

  1. Exchange public keys between sender and recipient
  2. Sender encrypts the message using the recipient's public key
  3. Recipient decrypts the message using their private key
  4. Optionally, sender can sign the message with their private key for authenticity
• What are the implications of using a 256-bit encryption key?

  • Extremely high number of possible combinations: $2^{256}$
  • Practically uncrackable with current technology
  • Takes billions of years to crack via brute force
  • Provides strong security for sensitive information