Encryption - Symmetric Key vs Asymmetric Key - AWS Certification Cheat Sheet

Let’s get a quick overview of Encryption - Symmetric Key vs Asymmetric Key.

You will learn

  • What is Encryption?
  • Why do we need Encryption?
  • When do we use Encryption - Symmetric Key vs Asymmetric Key?
  • How is Symmetric Key Encryption different from Asymmetric Key Encryption?
  • What are different Data States?

Data States

  • Data at rest: Stored on a device or a backup
    • Examples : data on a hard disk, in a database, backups and archives
  • Data in motion: Being transferred across a network
    • Also called Data in transit
    • Examples :
      • Data copied from on-premise to cloud storage
      • An application in a VPC talking to a database
    • Two Types:
      • In and out of AWS
      • Within AWS
  • Data in use: Active data processed in a non-persistent state
    • Example: Data in your RAM


  • If you store data as is, what would happen if an unauthorized entity gets access to it?
    • Imagine losing an unencrypted hard disk
  • First law of security : Defense in Depth
  • Typically, enterprises encrypt all data
    • Data on your hard disks
    • Data in your databases
    • Data on your file servers
  • Is it sufficient if you encrypt data at rest?
    • No. Encrypt data in transit - between application to database as well.

Symmetric Key Encryption

  • Symmetric encryption algorithms use the same key for encryption and decryption
  • Key Factor 1: Choose the right encryption algorithm
  • Key Factor 2: How do we secure the encryption key?
  • Key Factor 3: How do we share the encryption key?

Asymmetric Key Encryption

  • Two Keys : Public Key and Private Key
  • Also called Public Key Cyptography
  • Encrypt data with Public Key and decrypt with Private Key
  • Share Public Key with everybody and keep the Private Key with you(YEAH, ITS PRIVATE!)
  • No crazy questions:
    • Will somebody not figure out private key using the public key?
  • How do you create Asymmetric Keys?

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