In recent years, Internet changes our life a lot. We use e-mail and Internet phone to talk with
our friends, we get up-to-date information through web and we do shopping in the cyber-market.
Internet has many advantages over traditional communication channels, e.g. it's cost effective, it
delivers information fast and it is not restricted by time and place. The more people use Internet,
the more concerns about Internet security.
In person-to-person community, security is based on physical cues. To name but a few, we
use our signature to authenticate ourselves; we seal letters to prevent others inspection and
modification; we receive receipt with the shop's chop to make sure we paid; we get information
from a reliable source. But in the Internet society, no such physical cue is available. There are
two areas that we concern about in Internet communication. The first one is secrecyhow do we
ensure no one reads the data during its transmission? The second one is authenticationhow do
we be sure that the identity of someone claiming "who it is". Imagine one day you receive an
e-mail, which the e-mail sender is "Bill Gates". How do you confirm the e-mail is actually sent
by Bill Gates?
Encryption is the way to solve the data security problem. In real life, if Tom wants to talk with
Mary secretly, he can choose a room with nobody there and talk with Mary quietly, or he can talk
with Mary using codes understandable by Tom and Mary only. We take the second approach
encryptionto transmit data through Internet. There are two kinds of encryption techniques
symmetric key encryption and asymmetric key encryption.
For symmetric key encryption, both parties should have a consensus about a secret encryption key.
When A wants to send a message to B, A uses the secret key to encrypt the message. After receiving the
encrypted message ,B uses the same (or derived)secret key to encrypt the message.The advantage of
using symmetric key encryption lies in its fast encryption and decryption processes(when compared
with asymmetric key encryption at the same security level). The disadvantages are , first, the encryption
key must be exchanged between two parties in a secure way before sending secret messages. Secondly,
we must use different keys with different parties. For example, if A communicates with B, C, D and E,
A should use 4 different keys. Otherwise, B will know what A and C as well as A and D has been
talking about. The drawbacks of symmetric key encryption make it unsuitable to be used in the Internet,
because it's difficult to find a secure way to exchange the encryption key.
For asymmetric key encryption, there is a pair of keys for each party: a public key and a
private key. The public key is freely available to the public, but only the key owner gets hold of
the private key. Messages encrypted by a public key can only be decrypted by its corresponding
private key, and vice versa. When A sends message to B, A first gets B's public key to encrypt
the message and sends it to A. After receiving the message, B uses his private key to decrypt the
message. The advantage comes in the public key freely available to the public, hence free from
any key exchange problem. The disadvantage is the slow encryption and decryption process.
Almost all encryption schemes used in the Internet uses asymmetric key encryption for
exchanging the symmetric encryption key, and symmetric encryption for better performance.
Asymmetric key cryptography seems to attain secrecy in data transmission, but the authentication
problem still exists. Consider the following scenario: when A sends a message to B, A gets B's
public key from the Internetbut how can A know the public key obtained actually belongs to B?
Digital certificate emerges to solve this problem.
Digital certificate is an identity card counterpart in the computer society. When a person
wants to get a digital certificate, he generates his own key pair, gives the public key as well as
some proof of his identification to the Certificate Authority (CA). CA will check the person's
identification to assure the identity of the applicant. If the applicant is really the one "who
claims to be", CA will issue a digital certificate, with the applicant's name, e-mail address and the
applicant's public key, which is also signed digitally with the CA's private key. When A wants to
send B a message, instead of getting B's public key, A now has to get B's digital certificate. A
first checks the certificate authority's signature with the CA's public key to make sure it's a
trustworthy certificate. Then A obtain B's public key from the certificate, and uses it to encrypt
message and sends to B.
Authentication is an important part everyday life. The lack of strong authentication has
inhibited the development of electronic commerce. It is still necessary for contracts, legal
documents and official letters to be produced on paper. Strong authentication is then, a key
requirement if the Internet is to be used for electronic commerce. Strong authentication is
generally based on modern equivalents of the one time pad. For example tokens are used in place
of one-time pads and are stored on smart cards or disks.
 Many people pay great amounts of lip service to security, but do not want to be bothered
with it when it gets in their way. It's important to build systems and networks in such a way that
the user is not constantly reminded of the security system around him. Users who find security
policies and systems too restrictive will find ways around them. Security is everybody's business,
and only with everyone's cooperation, an intelligent policy, and consistent practices, will it be
1, cue [kju:]
2, chop [tʃɔp]
3, secrecy ['si:krəsi]
4, symmetric [si'metrik]
5, asymmetric [,eisi'metrik]
6, consensus [kən'sensəs]
7, cryptography [krip'tɔɡrəfi]
Continue reading it-e-57 Internet Security
It might be a stretch to call the recent "Melissa" virus a positive event because it disrupted
thousands o government and commercial computer systems. But it did put the focus on content
filtering, a network security technology that observers say has been undervalued. In the long run,
many believe this new focus will prove beneficial to users.
As a macro virus attached to an e-mailed Microsoft Corp. Word document, Melissa would
not have been picked up by traditional security solutions such as firewalls or intrusion-detection
systems, which are designed to detect items that break certain global access rules. The only way
to detect a virus such as Melissa is to examine what is inside the e-mail, which can only be done
through content filtering, supporters of the technology said.
Filtering products have been around for years, but manufacturers have been struggling to
meet the needs of organizations that employ varying security policies among different users.
Recently, however, vendors have released filtering products that can be tailored to the needs of
user groups, and industry has begun working on standards that allow these products to work with
Content filtering encompasses several areas of protection. As well as guarding against
viruses, it includes:
E-mail filtering, which controls incoming e-mail that contains spam, file attachments that
are too large or hoax e-mails. It also can be used internally to make sure confidential information
is not accidentally or intentionally sent outside of the organization.
Uniform Resource Locator filtering, which blocks access to inappropriate sites not connected
to a user's work needs.
Malicious-code protection, which prevents hostile code embedded in Java and ActiveX
scripts in otherwise innocuous World Wide Web pages from reaching the user's browser and
The most obvious benefit of filtering products is the ability to boost network security, but
many organizations also use them for internal network control. For example, URL filters can be
used to block access to certain sites and to maintain productivity. Message Inspector, an e-mail
filter produced by Elron Software Inc. uses context-sensitive filtering to weed out offensive or
sensitive communications in e-mail, newsgroups or FTP sites. Message Inspector is an example
of the newer generation of filter products that examine messages for words and phrases used in
conjunction with each other to narrow the range of filter targets. This strategy differs from the
one employed by traditional products that block communications based on factors such as
keywordsa process that can generate a lot of "false positive" alarms.
Melissa presented a clear idea of why people need a gateway-based virus-detection product,
"Viruses need to be kept out of the enterprise altogether because you just can't update all
virus-detection software on desktops in time to catch them."
The International Computer Security Association is working on what it calls the Common
Content Inspection program to define a general application program interface (API) that would
enable filter vendors to fit their products to a range of firewalls.
1, disrupt [dis'rʌpt]
2, hoax [həuks]
Continue reading it-e-56 Content Filtering Sifts out Viruses
Backdoor programs are typically more dangerous than computer viruses, as they can be
used by an intruder to take control of a PC and potentially gain access to an entire network.
Backdoor programs, also referred to as Trojan horses, are typically sent as attachments to
e-mails with innocent-looking file names, tricking users into installing them. They often enable
remote users to listen in on conversations using the host computer's microphone, or even see
through its video camera if it has one. Back Orifice (BO) 2000 is a backdoor program designed
for malicious use. Its main purpose is to maintain unauthorized control over another machine for
reconfiguration and data collection. It takes the form of a client/server application that can
remotely control a machine without the user's knowledge to gather information, perform system
commands, reconfigure machines and redirect network traffic.
With BO an intruder has to know the user's IP address to connect, or could scan an entire
network looking for the victim. Once connected, the intruder can send requests to the BO 2000
server program, which performs the actions the intruder specifies on the victim's computer,
sending back the results.
BO is installed on the server machine simply through the execution of the server application.
This executable file is originally named bo2k.exe, but it can be renamed. The configuration wizard
will step through the various configuration settings, including the server file (the executable), the
network protocol, port number, encryption, and password. Once this process is complete, running
bo2kgui.exe executes the user interface for BO.
It is very difficult to detect BO, because it is so highly configurable. In addition, backdoor
programs are multi-dimensional, so several detection methods are recommended to achieve maximum
protection and awareness of the installation of BO 2000 on a machine or series of machines on a
We recommend coupling the use of an updated version of anti-virus software to detect
which machines on the network have BO installedand intrusion detection software to identify
attacks over the network.
Users are urged to follow three important precautions:
Do not accept files from Internet chat systems.
If you are connected to the Internet, do not enable network sharing without proper security
Do not open e-mail attachments: never run any executable files sent to you (.exe files or .zip
files with a.exe in them). It is safer if these are run through a virus checker first, but they could be
new backdoor programs or viruses that a virus scanner will not detect. It is safe to open Word
documents and Excel spreadsheets if the Microsoft Auto-Run feature is turned off. Allowing
macros to run automatically can spread e-mail viruses such as Melissa. Many people send each
other animations in e-mail: it is easy to put a backdoor program into one of these and users
cannot tell when they infect their computers with Back Orifice 2000.
1, potentially [pə'tenʃəli]
Continue reading it-e-55 Backdoor
Continue reading FTP连接后出现无法显示列表或列表错误问题的解决方法
Just as human viruses invade a living cell and then turn it into a factory for manufacturing
viruses, computer viruses are small program that replicate by attaching a copy of themselves to
another program. Once attached to the host program, the virus then lock for other programs to
"infect". In this way, the virus can spread quickly throughout a hard disk or an entire organization if
it infects a LAN (Local Area Network) or a multi-users system.
 Skillfully written virus can infect and multiply for weeks or months without being detected.
During that time, system backups duplicate the viruses, or copies of data or programs made and
passed to other systems to infect. At some pointdetermined by how the virus was programmed
the virus attacks. The timing of the attack can be linked to a number of situations, including: a
certain time or date; the presence of a particular user ID; the use or presence of a particular file; the
security privilege level of the user; and the number of times of a file is used.
Likewise, the mode of attack varies, so-called "being" viruses might simply display a
message, like the one that infected IBM's main computer system last Christmas with a season's
Malignant viruses, on the other hand, are designed to damage your system. One common
attack is to wipe out data, to delete files, or to perform a format of disk.
There are four main types of viruses: shell, intrusive, operating system, and source code.
Shell viruses wrap themselves around a host and do not modify the original program.
Shell program are easy to write, which is why about half of all viruses are of this type. In
addition, shell viruses are easy for programs like Data Physician to remove.
Intrusive viruses invade an existing program and actually insert a portion of themselves
into the host program. Intrusive viruses are hard to write and difficult to remove without
damaging the host file.
Shell and intrusive viruses most commonly attack executable program filethose with.
COM or. EXE extensionalthough data are also at some risk.
Operating system viruses work by replacing parts of operating system with their own
logic. Very difficult to write, these viruses have the ability, once booted up, to take
total control of your system. According to Digital Dispatch, known versions of operating
system viruses have hidden large amounts of attack logic in falsely marked bad disk
sectors. Others install RAM-resident programs or device drivers to perform infection or
attack functions invisibly from memory.
Source code viruses are intrusive programs that are inserted into a source program
as those written in Pascal prior to the program being compiled. These are the least
common viruses because they are not only hard to write, but also have a limited number
of hosts compared to the other types.
New computer viruses are written all the time, and it's important to understand how your
system can be exposed to them and what can do to protect your computer. Follow the suggestions
listed below to substantially decrease the danger of infecting your computer system with a
potentially dangerous computer virus.
Be very cautious about inserting disks from unknown sources into your computer.
Always scan the disk's files before operating any of them.
Only download Internet files from reputable sites.
Do not open e-mail attachments (especially executable files) from strangers.
Purchase, install, and use an anti-virus software program. The program you choose must
provide three functions:
As new viruses are created everyday, upgrade your anti-virus software regularly.
1, invade [in'veid]
2, replicate ['replikit, 'replikeit]
3, wipe [waip]
Continue reading it-e-54 Computer Viruses
不过目前最新safari只能在mac os系统下面才能提供webgl 见http://www.khronos.org/webgl/wiki_1_15/index.php/Getting_a_WebGL_Implementation#Safari。
OpenGL Shading Language Specification
OpenGL Shading Language Tutorials
OrangeBook's Web Site
Continue reading webGL入门
In the traditional, manual working environment, information (in the form of texts, numbers,
etc.) and medium (such as paper) were closely intertwined. Long experiences in their usage and
the application of anti-counterfeit technology have made traditional forms of information very
difficult to alter. Similarly, it was also difficult to send bogus information by an impersonator.
Even those who succeeded in doing so usually were discovered very easily. In today's world of
information and technology, the Internet is rapidly changing many ways people do things.
Similarly, it has also introduced many management problems. For man and information to
interact, there is a need to establish a reliable information system working environment in which
we grasp, distribute, store and manage information. Such an environment must be able to provide
ample protection against tampering, stealing, delaying, transmission by fictitious parties, denial
of having faxed a document, illegal intrusion and the like. Only so can we build a strong
foundation for an information society.
Security in the process of transmission, data resemble all the cash in a bank armored van. It
can be lost or robbed anytime. With the purpose of maintaining data transmission security on the
Internet, most people use encryption technology. Data to be transmitted is first encrypted as a
way to prevent snooping or theft. The "Public-Key Cryptographic System" has the functions of a
"digital signature" and requires no prior exchange of keys while offering the advantages of
"secret communication." To make this system work smoothly, it is first necessary to agree and
certify beforehand as to who or which institution holds a certain key. This goes to say that a
certification management system must first be established to handle issuance or revocation of
electronic certification. In addition to this system, all matters related to its usage and application
services must form part of the basic operations framework of the whole system.
The first important thing in maintaining data security is the periodic making of back-ups.
Personal computer users must periodically make back-ups of data using different back-up tools
(such as diskettes, magnetic tape, removable hard drives, etc.) and store them in a safe location. If
and when data from a personal computer is damaged and cannot be recovered, the back-up copies
will serve their purpose. Thus, the first step in data security is to develop the habit of making
periodic back-ups. It is the most effective way to assure data security under extreme circumstances.
There are many factors that pose a threat to data security. They include viruses, deliberate acts of
sabotage and theft. Users can guard against them using the following methods: Use a protection
password for access to personal computers and the Internet. This prevents the unauthorized from
stealing or damaging data inside personal computers. Handle files with encryption protection and
decipher only when necessary. In this way, even if files are stolen, encryption would still be
necessary to use the files. Files transmitted through the Internet must first be encrypted. The
Internet is an open environment where anybody can intercept data during transmission. Encryption
of such data is an effective way to prevent unwanted disclosure. Respect intellectual property rights
by refraining from using software programs of dubious sources. This way, viral attack can be
avoided or the use of Trojan Horse by the unscrupulous to steal data can be thwarted.
Passwords and names of users of databases and application programs must be kept
confidential. Avoid using birth dates, telephone numbers and other readily accessible figures as
passwords. They must be handled carefully and recorded in secret locations. Periodic changing of
passwords is also recommended. Print-outs of application software programs no longer used must
be shredded to prevent disclosure of data. Build up a no-diskette system environment to avoid
computer virus contamination.
To guarantee data security, the Information Department must, in addition to setting up
comprehensive regulations, ensure cooperation by users. Their usage of computer equipment
according to regulated procedures contributes to the effective maintenance of data security.
It is necessary to build up a data security audit system that includes periodic and random
spot checks and testing of information security and protection operations, as well as conduct
tracking and improvement of deficiencies.
1, intertwined [,intə:'waind]
2, bogus ['bəuɡəs]
3, impersonator [im'pə:səneitə(r)]
4, grasp [ɡrɑ:sp, ɡræsp]
5, tampering ['tæmpəriŋ]
6, fictitious [fik'tiʃəs]
7, van [væn]
9, revocation [,revə'keiʃən]
10, decipher [di'saifə]
12, thwart [θwɔ:t]
13, unscrupulous [ʌn'skru:pjuləs]
14, conduct ['kɔndʌkt, kən'dʌkt]
Continue reading it-e-53 The Development of Data Transmission
例如：使用脚本向一个iframe里面写日志doc.body.innerHTML += ‘<div>…</div>’;
Continue reading IE SaveAs命令问题
The information security system is an integral part of the national security system. The main
functions of the information security system are:
assessing the state of information security in the country, identifying and forecasting
internal and external threats to information security, drafting an information security
developing a comprehensive system of legal, administrative, economic, technical and
other measures and methods aimed at ensuring information security;
coordinating and monitoring the work of information security entities;
protecting information security entities against incomplete, inaccurate and distorted
information and against exposure to information damaging to their life and health;
protecting protected information;
counteracting technical intelligence services;
developing and perfecting an information infrastructure, an information technology
industry, systems, means and services;
organizing scientific research, developing and implementation of scientific,
scientific-technical programmes in the field of information security;
licensing the activities of corporations and individual entrepreneurs in the field of
certifying information systems and means, assessing and rating the compliance of
information facilities with information protection requirements;
state inspection in the field of information security;
creating conditions for preserving and developing intellectual potential in the
preventing, identifying and suppressing offences which are aimed at hurting the rights
and freedoms of corporations and individuals in the information sphere, prosecuting and
trying in court perpetrators of crimes in the information sphere;
carrying out international cooperation in the sphere of information security.
1, integral ['intigrəl]
n. [数学] 积分, 完整, 部分
2, assess [ə'ses]
3, doctrine ['dɔktrin]
4, distorted [dis'tɔ: tid]
a. 扭歪的, 受到曲解的
5, counteract [,kauntə'rækt]
6, sphere [sfiə]
7, perpetrator [,pə:pi'treitə]
Continue reading it-e-52 Information Security System
The issue of information security and data privacy is assuming tremendous importance among
global organizations, particularly in an environment marked by computer virus and terrorist attacks,
hackings and destruction of vital data owing to natural disasters.  When it comes to information
security, most companies fall somewhere between two extreme boundaries: complete access and
complete security. A completely secure computer is one that is not connected to any network and
physically unreachable by anyone. A computer like this is unusable and does not serve much of a
practical purpose. On the other hand, a computer with complete access is very easy to use, requiring
no passwords or authorization to provide any information.  Unfortunately, having a computer with
complete access is also not practical because it would expose every bit of information publicly,
from customer records to financial documents. Obviously, there is a middle ground this is the art
of information security.
The concept of information security is centered on the following components:
Integrity: gathering and maintaining accurate information and avoiding malicious modification
Availability: providing access to the information when and where desired
Confidentiality: avoiding disclosure to unauthorized or unwanted persons
For an information system to be secure, it must have a number of properties:
 service integrity. This is a property of an information system whereby its availability,
reliability, completeness and promptness are assured;
data integrity. This is a property whereby records are authentic, reliable, complete, unaltered
and useable, and the processes that operate on them are reliable, compliant with regulatory
requirements, comprehensive, systematic, and prevent unauthorized access, destruction, alteration
or removal of records. These requirements apply to machine-readable databases, files and archives,
and to manual records;
data secrecy . This is a property of an information system whereby information is available
only to those people authorized to receive it. Many sources discuss secrecy as though it was only
an issue during the transmission of data; but it is just as vital in the context of data storage and
authentication. Authentication is a property of an information system whereby assertions
are checked. Forms of assertion that are subjected to authentication include:
"data authentication", whereby captured data's authenticity, accuracy, timeliness,
completeness and other quality aspects are checked;
"identity authentication", whereby an entity's claim as to its identity is checked.
This applies to all of the following:
the identity of a person;
the identity of an organizational entity;
the identity of a software agent; and
the identity of a device.
"attribute authentication", whereby an entity's claim to have a particular attribute is
checked, typically by inspecting a "credential". Of especial relevance in advanced
electronic communications is claim of being an authorized agent, i.e. an assertion by a
person, a software agent or a device to represent an organization or a person.
Non-repudiation. This is a property of an information system whereby an entity is unable
to convincingly deny an action it has taken.
There is a strong tendency in the information systems security literature to focus on the
security of data communications. But security is important throughout the information life-cycle,
i.e. during the collection, storage, processing, use and disclosure phases, as well as transmission.
Each of the properties of a secure system identified above needs to be applied to all of the
information life-cycle phases.
1, tremendous [tri'mendəs]
2, malicious [mə'liʃəs]
3, disclosure [dis'kləuʒə]
4, promptness [prɔmptnis]
5, whereby [(h)wєə'bai]
7, literature ['litəritʃə]
Continue reading it-e-51 Concept of Information Security