Tuesday, March 31, 2015

What is SSL (Secure Sockets Layer)? (14 of 285 technotes for 2015)

  • SSL is a security protocol for the transport layer.
  • A protocol is  guideline to define how an algorithm should be written.
  • SSL encrypts the messages between the web server and the browser.
SSL Certificate:
  1. Browser and the server need SSL Certificate to establish a secure connection.
  2. SSL Certificates have a key pair: a public and a private key 
  3. It also contains the “subject,” which is the identity of the certificate/website owner.
  4. Steps to create a SSL Certificate:
    1. Create a CSR (Certificate Signing Request) on your server.
    2. CSR contains a private key and a CSR data file.
    3. Send the CSR to SSL Certificate issuer (Certificate Authority)
    4. CA creates a public key to match your private key (using the CSR data file, and without seeing the private key)
    5. The SSL certificate contains the public key
    6. U install the SSL certificate in your server (Read more about intermediate certificates and certificate chaining in the links below)

  1. Browsers trust certificate that come only from trusted CA’s
  2. Browsers come with a pre listed trusted CA’s - Trusted Root CA store
  3. This shows that a third party have verified organization’s identity
  4. SInce browser trust the CA, it trusts the certificate and the domain details in the certificate.
  5. Browser lets the user know the website is secure.
Flowchart - SSL Handshake:
NOTE: data encrypted with public key can only be decrypted with the private key and vice versa
  1. Browser attempts to connect to a server using SSL
  2. Server sends its SSL Certificate (containing the public key)
  3. Browser checks the CA within its list of known CA’s. If it is good, it creates, encrypts (using the public key) and sends a symmetric session key. (Session key is used to reduce processing cost)
  4. Server - decrypts the symetric session key using the private key to start the encrypted session
  5. Server and Browser continue communication using the session key

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Once secured connection is established the browser address bar will look something like the picture below


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References: http://bit.ly/1xToPSG

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