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COMPUTER SYSTEMS

TOPIC 4B: PRECAUTIONS

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LEARNING INTENTIONS

Describe how encryption is used to secure transmission of data:

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• use of public and private keys

• digital certificates

• digital signatures

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ENCRYPTION

Encryption is when data is encoded into another form. If data is intercepted then the data is meaningless until it is deciphered using a key.

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There are two types of encryption in widespread use today:

symmetric and asymmetric encryption.

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SYMMETRIC

In symmetric-key encryption, each computer has a secret key (code) that it can use to encrypt a packet of information before it is sent over the network to another computer. Symmetric-key requires that you know which computers will be talking to each other so you can install the key on each one.

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PROBLEM SYMMETRIC

When these keys are shared over an unsecured connection, they are vulnerable to being intercepted by malicious third parties.

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Additional Reading

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Video

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ASYMMETRIC (PUBLIC KEY)

Two encryption keys (public and private) are used to scramble data so that it cannot be intercepted.

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Public key - known by everyone and is used to encrypt the message.

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Private key - known only by the recipient and is used to decrypt the message.

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DIGITAL CERTIFICATES

A Digital Certificate is an electronic "password" that allows a person, organisation to exchange data securely over the Internet using the public key infrastructure.

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Digital Certificate is also known as a public key certificate or identity certificate.

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The Internet is an open communications network that was not originally designed with security in mind.

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DIGITAL SIGNATURE

  • A digital signature is a way to ensure that an electronic message or document is authentic.
  • The signature is created when the message is sent, using a private encryption key.
  • This is the opposite to normal Public Key Encryption.
  • The signature is then paired with a public key and sent with the message. When the message run through the public key the result should match the signature.
  • If they don’t match then the message has been altered en route. This shows that the message has been intercepted and compromised.

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