Cisco Securit y

transcript

Cisco Security

An Example

=> How to transport the letter safely ?

=> Worry somebody intercept the letter ?

=> Worry somebody falsify the letter ?

=> Worry writter or transporter negative the letter ?

Security Meaning

=> Ensure the source

=> Ensure the message could not be falsify or intercept

while transportion

=> Ensure the message could not be cracked

=> No negation

Basics of Encryption

There are two types of encryption keys:

=> Symmetric

=> Asymmetric

Symmetric

With symmetric key encryption, each peer uses the same

key to encrypt and decrypt the data.

Symmetric Encryption

Maybe Perfect

An Obvious Problerm

=> How to send the "key" ?

=> QQ ? MSN ? E-mail ? Telephone ?

=> Bike ? Bus ? Train ? Airplane ?

Asymmetric

With asymmetric key encryption, the local end uses one

key to encrypt,and the remote end uses another key to

decrypt the traffic.

Asymmetric Encryption

Maybe Perfect

An Obvious Problem

=> Cracker will exchange the letter . How to solve this

problerm ?

A perfect Encryption

A Perfect Decryption

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