Computer Networks Prof. Hema A Murthy
Network Security
Security
Crytographic algorithms Security Services
Secret key Public key Message digest privacy authenticity Message
(DES) (RSA) (MD5) integrity
Indian Institute of Technology Madras
,Computer Networks Prof. Hema A Murthy
Secret Key Encryption
Plain text Plain text
Encrypt using Decrypt using
secret key secret key
Indian Institute of Technology Madras
,Computer Networks Prof. Hema A Murthy
Public Key Encryption
• Each participant has a secret key (private
key)
• The key is not stored
– Publish on the web (for instance)
• To send a message
– Encrypt with public key
– To decrypt, decrypt using a private key
Indian Institute of Technology Madras
Network Security
Security
Crytographic algorithms Security Services
Secret key Public key Message digest privacy authenticity Message
(DES) (RSA) (MD5) integrity
Indian Institute of Technology Madras
,Computer Networks Prof. Hema A Murthy
Secret Key Encryption
Plain text Plain text
Encrypt using Decrypt using
secret key secret key
Indian Institute of Technology Madras
,Computer Networks Prof. Hema A Murthy
Public Key Encryption
• Each participant has a secret key (private
key)
• The key is not stored
– Publish on the web (for instance)
• To send a message
– Encrypt with public key
– To decrypt, decrypt using a private key
Indian Institute of Technology Madras
