網際網路應用系統設計 作業七 ( 5/9 Homework)

3.1秘密鑰匙系統有何優缺點?

Secret key or privacy key is a system that uses the same key to decryption and encryption.

Thumb up:

It can use for self-security for encrypting data on hard drive. People won’t have the chance to steal the key when transit. For example, compressed files can encrypt by secret key.

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Everyone who has the key can decrypt the message. It’s not so reliable when you want to tell the key to another. The key may be compromised when transit.

http://www.linktionary.com/s/secret_key.html

http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci518887,00.html

3.2公開金鑰系統如何防止第三者竊取資料?

In a public-key cryptosystem, a user makes use of a pair of keys: a public key and a private key.

The privacy key can keep by one. It’s not necessary to tell anyone else. So we don’t have the security problem to send the message though internet. The only way to decrypt the message is the privacy key which encrypt by corresponding public key.

http://www.webopedia.com/TERM/P/public_key_cryptography.html

http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci214299,00.html