The Internet Book

1
The Internet Book
2
Chapter 29
3
The Internet Is Unsecure

• Many networks are shared meaning multiple
  computer are attached.
• Lacking security
• Eavesdroping on other customers
• Shared bandwidth (cable modem)

4
Lack of Security Can Be Important

• Lack of security can pose a serious risk.
• Using
• Confidential memos
• Financial transactions

5
Authentication And Privacy Are Primary Problems

• The authentication problem is
• Verifying the identity of the communicating party
• The privacy problem is
• Keeping data across the Internet confidential

6
Data May Be Changed

• Data passes through the Internet
• Changing of data is a potential risk
• Guaranteeing data remains unchanged can be done
  through some Internet technologies

7
Encoding Keeps Messages Private

• Before sending a message, software on the sending
  computer
• Encodes the contents of the message
• When receiving a message, software on the
  receiving computer
• Decodes the message

8
Computer Encryption Uses Mathematics

• Human encryption is too easy to decode.
• The Internet uses sophisticated encoding.

9
No Network Is Absolutely Secure

• Encryption cannot guarantee privacy.
• Breaking the code will take so long, the security
  is considered to be sufficient

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Encryption Makes E-mail Private

• Figure 29.1 Encryption software ensures that the
  contents of an e-mail message remains private.
  Only the encrypted version passes across the
  Internet.

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Encryption Software Needs A Key

• Each user is assigned a key that only unlocks
  messages encrypted for the user.
• Without the key, no one can decrypt messages for
  the user.

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Two Keys Means Never Having To Trust Anyone

• One key is to encrypt messages.
• Use the private key
• The other key is to decrypt messages
• Use the public key

13
Two Keys Means Never Having To Trust Anyone

• Businesses keep the private key private and share
  the public key with customers.
• Using the public key, anyone can send
  confidential messages
• Decrypting can be done only with the private key.

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Figure 29.2
Figure 29.2 An illustration of the keys used when
two individuals exchange confidential
communication. Messages sent across the Internet
between the two computer are always encrypted,
but the key used for encryption depends on the
destination.
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Secure E-Mail In Practice

• No single encryption technology has emerged as
  the universal standard.
• Allowing backward compatibility
• Secure Multipurpose Internet Mail Extensions
  (SMIME)
• Not allowing backward compatibility
• Pretty Good Privacy (PGP)

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Conclusion

• What security is needed for Internet
  communication?

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Glossary

• Cable modem
• A device that allows Internet service to be
  provided over the same coaxial cable wiring used
  for cable television.
• Encryption
• The process of encoding a message to keep it
  confidential.

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Glossary

• Unsecure
• A computer or a network in which information is
  not protected against being copied or changed.