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Cisco Securit y. 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
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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 peeruses thesame key to encryptand decrypt the data.
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.
An Obvious Problem • => Cracker will exchange the letter . How to solve this • problerm ?