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Understanding Network Security: Symmetric and Asymmetric Encryption Techniques

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This overview explores essential concepts in network security, focusing on symmetric and asymmetric encryption methods. Symmetric encryption uses a single secret key for both encryption and decryption, while asymmetric encryption employs a public key for encryption and a private key for decryption. The importance of digital signatures, which verify message authenticity, and digital certificates issued by certificate authorities are also discussed. Additionally, we delve into the implications of password cracking and the necessity of strong encryption, emphasizing key size in relation to computational power.

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Understanding Network Security: Symmetric and Asymmetric Encryption Techniques

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Presentation Transcript

  1. Advanced Higher ComputingComputer Networking Topic 5: Network Security

  2. Symmetric Encryption • Data is encrypted using a secret key and an encryption algorithm Ciphertext • Data is decrypted using the same secret key and decryption algorithim

  3. Asymmetric Encryption • Data is encrypted using the recipient’s public key and an encryption algorithm Ciphertext • Data is decrypted using the recipient’s private key and decryption algorithim

  4. Digital Signature • A digital signature is a piece of code attached to a message which is calculated from the message and then encrypted using the sender’s private key • The signature can only be decrypted using their public key • This proves that the message came from them and that it has not been tampered with (so long as you know that the public key is genuine)

  5. Digital Certificates • A digital certificate is issued by a certificate authority which authenticates a person’s public key

  6. Network Architecture security • Client creates a random number and encrypts it with user’s secret key (password) • Server decrypts number, adds 1, re-encrypts it and sends it back to client • Client decrypts new number to confirm that it is authenticated • Server creates a session key which is used to encrypt any further messages

  7. Password cracking • If the encryption algorithm known and the encrypted password file is available then passwords can be decrypted using the Brute Force method

  8. Password cracking • Cracking program encrypts possible passwords • Program compares encrypted passwords with entries in the server’s password file • Program outputs any matched passwords

  9. Encryption Classification • Encryption is classified according to how many bits are in the secret key used to encrypt the data • As computers increase in power, the time taken to crack a password decreases, so the bit size of the secret key has to be increased • The value of any information is time dependent

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