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Symmetric vs Asymmetric Encryption


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Welcome to Symmetric vs. Asymmetric Encryption

Now you will learn why Encryption is a big part of Network Security!

In this Video we will: 

  • Present an overview of the two methods of encryption in use today.
  • Describe and illustrate Symmetric and Asymmetric encryption.
  • Explain the advantages and disadvantages of both methods of encryption.
  • At the end of this lecture you will understand the difference between Symmetric and Asymmetric encryption.

What is Encryption?  

Encryption is the process of encoding data to prevent unauthorized access.

There are two forms of encryption in common use today. Symmetric and Asymmetric.

With Symmetric Encryption

  • There is only one key
  • The same key encrypts and decrypts the data

Here is a video describing Symmetric key encryption

Let’s say you want to send me an email. You encrypt the email using your secret key, you send me the key.

I receive the email and decrypt it using the same key.

The problems with Symmetric Encryption

  • You must keep the key secret
  • The key will need to be transferred to the other party
  • Susceptible to attack – If a third party steals the key they will be able to decrypt the data and read the message.

Advantages of Symmetric encryption

• Very fast – The process of Symmetric Encryption is much faster than Asymmetric Encryption.

Asymmetric Encryption  

  • Consists of two keys (pairs)
  • The public key can be shared, given away – Sent in an email, posted on a web site.
  • The private key cannot be shared, keep it private
  • The private key is the only key that can decrypt data encrypted with the public key.
  • If someone encrypts data with the public key, the only way data could be decrypted is with the private key. That is why the private key must be kept private.

Here is a video describing Asymmetric Key Encryption

Let’s say you want to send me an email.

I have a key pair, you have a key pair. We both have each other’s public keys. If you want to send me a message I don’t have to share anything with you. You encrypt the email, with my public key.

You don’t have to send me anything because you know that I can decrypt the email with my private key.

I decrypt the email using my private key, now I can read the message.

Advantages of Asymmetric encryption

  • Very secure
  • The encryption can occur without the private key
  • The private key never needs to be transferred


  • Slower than Symmetric key encryption

Additional Considerations: 

  • Symmetric and Asymmetric encryption can be combined for additional flexibility.  
  • Microsoft DNSSEC or DNS Security is based upon Symmetric key encryption.

In this Video we: 

  • Presented an overview of the two methods of encryption in common use today.
  • Described and illustrated Symmetric and Asymmetric encryption
  • Explained the advantages and disadvantages of both methods of encryption
  • Now you should understand the differences between Symmetric and Asymmetric encryption.

Congratulations you have completed this lecture. I hope you found this lecture interesting. Thanks for watching and we will see you in the next lecture.

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