Netscape Certificate Management System 6.2, Руководство администратора

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Internet Security Issues
798 Netscape Certificate Manager System Administrator’s Guide • June 2003
The great flexibility of TCP/IP has led to its worldwide acceptance as the basic
Internet and intranet communications protocol. At the same time, the fact that
TCP/IP allows information to pass through intermediate computers makes it
possible for a third party to interfere with communications in the following ways:
• Eavesdropping. Information remains intact, but its privacy is compromised.
For example, someone could learn your credit card number, record a sensitive
conversation, or intercept classified information.
• Tampering. Information in transit is changed or replaced and then sent on to
the recipient. For example, someone could alter an order for goods or change a
person's resume.
• Impersonation. Information passes to a person who poses as the intended
recipient. Impersonation can take two forms:
• Spoofing. A person can pretend to be someone else. For example, a person can
pretend to have the email address
jdoe@netscape.com
, or a computer can
identify itself as a site called
www.netscape.com
when it is not. This type of
impersonation is known as spoofing.
• Misrepresentation. A person or organization can misrepresent itself. For
example, suppose the site
www.netscape.com
pretends to be a furniture store
when it is really just a site that takes credit-card payments but never sends any
goods.
Normally, users of the many cooperating computers that make up the Internet or
other networks don’t monitor or interfere with the network traffic that
continuously passes through their machines. However, many sensitive personal
and business communications over the Internet require precautions that address
the threats listed above. Fortunately, a set of well-established techniques and
standards known as public-key cryptography make it relatively easy to take such
precautions.
Public-key cryptography facilitates the following tasks:
• Encryption and decryption allow two communicating parties to disguise
information they send to each other. The sender encrypts, or scrambles,
information before sending it. The receiver decrypts, or unscrambles, the
information after receiving it. While in transit, the encrypted information is
unintelligible to an intruder.
• Tamper detection allows the recipient of information to verify that it has not
been modified in transit. Any attempt to modify data or substitute a false
message for a legitimate one will be detected.