Symmetric/ Asymmetric key algorithm

✅ Symmetric key algorithm

1. A sends message encrypted with B’s public key
   
2. B recieves and decrypts with B’s private key
   
3. B sends message encrypted with A’s public key
   
4. A recieves and decrypts with A’s private key
   

• Private key encryption
• Same key for encryption, decryption
• 👍🏻 faster
• 👎🏻 lack non-repudiation
• 👎🏻 large scale use
• 👎🏻 easy to decrypt

☑️ Symmetric algorithm

• DES: Data Encryption Standard
• 3DES
• IDEA: International Data Encryption Algorithm
• AES: Advanced Encryption Standard
• Blowfish
• Twofish
• RC Cipher suite
  • RC4: Stream cipher, SSL, WEP(wired equivalent privacy)

✅ Asymmetric key algorithm

• Public key encryption
• different key for encryption and decryption
• 👍🏻 solve key distribution challenge
• 👎🏻 slower
• ⭐️ public key: encryption

• ⭐️ private key: decryption

• asymmetric algrithm can be done in two ways

☑️ Asymmetric algorithm

• Diffie-Hellman

  • key exchange over internet
  • VPN tunnel
  • IPSec
  • 👎🏻 on path attacks
  • 👎🏻 person-in-the-middle attacks

• RSA

  • key exchange= key distribution
  • Encryption
  • Digital Signature
  • Prime numbers
  • Trapdoor function

• ECC: Ellipic Curve Cryptography

  • modible device
  • require less processing power
  • more efficient that RSA

1️⃣ Encrypt: public key, decrypt: private key

• public key: encrypt
  • shared with everyone
• private key: decrypt
  • only host can have the key

2️⃣ Encrypt: private key, decrypt: public key

• public key: decrypt
  • shared with everyone

• private key: encrypt

  • only host can have the key
• Digital Signature: used to verify oneself
  • that it is me who encrypted this file(who made the signature)
• everyone with public key can verify that it is you who signed the file

✅ Hybrid Encryption

1. A creates symmetric key
   
2. A encrypts and sends symmetric key with B’s public key
   
3. B recieves symmetric key and decrypts with B’s private key
   
4. B sends message encrypted with A’s public key
   
5. A recieves and decrypts with A’s private key
   
6. Now A and B can communicate using the symmetric key
   

✅ Digital Signature

• Digital Signature is consisted of three algorithm steps
• Key Creation Algorithm G: create public, private key pair of host
• Signature Creation Algorithm S: message m and private key to create signature σ

• Verify Signature Algorithm V: use message m, public key, signature σ to verify host

• 👍🏻 can verify the host who wrote the message
• 👍🏻 can function like a signature of the host
• 👍🏻 non-repudiation
• 👍🏻 operate against forgery
• 👍🏻 data integrity(checksum will be different)

☑️ Digital Signature Algorithm

• DSA: Digital Security Algorithrm
• RSA