CYBER SECURITY UNIT 1 PART 1 ppt.pptx

CYBER LAW( 18U3CKE608 )
ELECTIVE II

Information
• Information is organized or classified data, which has some meaningful
values for the receiver. Information is the processed data on which decisions
and actions are based.
• For the decision to be meaningful, the processed data must qualify for the
following characteristics −
• Timely − Information should be available when required.
• Accuracy − Information should be accurate.
• Completeness − Information should be complete.

Data Processing Cycle
• Data processing is the re-structuring or re-ordering of data by
people or machine to increase their usefulness and add
values for a particular purpose.
• Data processing consists of the following basic steps - input,
processing, and output. These three steps constitute the data
processing cycle.
• Input − In this step, the input data is prepared in some
convenient form for processing.
• Processing − In this step, the input data is changed to
produce data in a more useful form.
• Output −The result of the proceeding processing step is
collected. The particular form of the output data depends on
the use of the data. For example, output data may be pay-
checks for employees.

Quality of Information
• Quality of information is an important concept. Information quality
is a multi-attribute concept. If the attributes that define quality of
information are of good quality or of high value then the
information is said to have good quality.
The attributes of quality of information are:
• Timeliness- The speed at which the information is received.
Normally, faster the information better is its quality.
• Appropriateness- is the suitability matching of the receiver and
the information, more the suitability of the information to the
receiver, better its quality.
• Reliability – the reliability of information is a key attribute of
quality. Only if the information is reliable is it of any use.
• Accuracy – is the correctness of the information. Normally, the
higher the accuracy of the information, the better is its quality.
• Completeness – is the measure of comprehensiveness. It is
required to ensure that the information provided gives the
complete picture of reality and not a part of the picture.

Value of Information
• Its value is related to the person who uses it,
when he uses it and for what he uses it.
• Value of information (VOI or VoI) is the amount a
decision maker would be willing to pay for
information prior to making a decision.
• In your academic, personal, and professional
lives, you need to assess the value of
information so that you can make wise decisions
with your money and solve problems using the
best information possible.
• Information of business value is that which is
needed to carry out business functions or to
provide evidence of a business activity.

Information processing
• Information processing is the process of changing
or converting information into meaningful form.
• Information is a processed, organized or classified
data which is useful for the receiver.
• Information is the processed data which may be
used “as is” or may be put to use along with more
data or information.
• The receiver of information takes actions and
decisions based on the information received.
• Collected data must be processed to get meaning
out of it, and this meaning is obtained in the form
of information.

Characteristics of Information
• Timely − Information should be available when
required, a delay in obtaining information renders it
useless.
• Accuracy − Accuracy of information has a significant
impact on the decision-making. Possibilities of even
slightest errors should be minimized
• Completeness − Information should be complete.
Incomplete information causes incorrect and
unintended results.
• Comprehensive – Information which is
incomprehensible is useless for the receiver. This
becomes a case of information failure as the sender
sent the information, but it was of no use for the
receiver, thus is not considered as “information.”

• Information processing cycle is a sequence of events consisting
of input, processing, storage & output.
• Input – Entering data into the computer
– Feeding the collected raw data in the cycle for processing.
This is the raw data which is supplied for processing &
obtaining information.
– Input can be done by utilizing various devices such as
keyboards, mice, flatbed scanners, barcode readers,
joysticks, digital data tablets (for graphics drawing),
electronic cash registers, etc
• Processing – Performing operations on the data
– Once the input is provided the raw data is processed by a
suitable or selected processing method. This is the most
crucial step as it allows for the processed data in the form of
output which will be used further.
– Processing is usually done by CPU (Central Processing Unit) in
a computer. CPU is the crucial component for getting the
operations done.

• Storage – Saving data in a soft/physical form
– This is the outcome, and the raw data provided in the first
stage is now “processed,” and the data is useful and provides
information and no longer called data.
– Storage can be done on external hard disk, inbuilt hard disk,
pen drives, micro SD cards, compact disks or even in
registers.
• Output – Results obtained, i.e., information
– This is the outcome, and the raw data provided in the first
stage is now “processed,” and the data is useful and provides
information and no longer called data. This might be further
used for data visualisation.
– This can be used as it is or used for further processing along
with more data.
•

Information representation in
computers
• Basic information units used in computers are:
bits, bytes and words.
• A byte is composed of 8 bits.
• A word contains a larger bit number, which correspond to
the length of registers used for fixed-point computations.
• Word length is a multitude of bytes to enable physical
memory addressing in bytes.
• In a computer word of n bits 2n bit combinations can be
registered and so 2n different information’s can be
encoded.
• The ASCII code (American Standard Code for Information
Interchange) has been designed by the American
Association for Information Interchange in the USA.

• It is a standard code used in computers to
encode in bytes the following items:
• numerical characters (letters and digits) - 7-bit
code,
• special symbols (+, -, =, !, ? etc) - 7-bit code,
• control characters: change of line, carriage
return, beginning of the text, end of the text -
7-bit code,
• special graphical signs - 8-bit code.

Data Representation
• Character and numbers are understandable
and usable by people therefore people feed
them to the computer and they expect the
result of computation or interaction from
computer as output many time in the same
form
• i.e, characters of text of character after
processing must appear for them as in English
like natural language and processed numbers
or results as represented in decimal and in
accordance with mathematical notation.

External Data Representation
• External Data Representation:
Natural language characters and decimal
numbers are usual be and understandable by
the people and termed as External Data
Representation.
• But as such the computer being electronic
machine cannot understand and use natural
language symbols and decimal numbers directly.
• External data Representation does not hold good
for computations inside the machine.

Internal Data Representation
The internal representation of data inside the
computer machine must be acceptable by machine
and suit the electronic concepts.
This led to the development of separate machine
language which is in binary form; consequently the
data to be processed must also be in binary form.
Different methods of representing natural language
symbols and decimal numbers in binary form inside
the machine constitute internal data representation.

• The characters and numbers are fed to the
computer machine and the results produced
from the machine, must be in a form that is
usable and understandable to the external
world; irrespective of internal data
representation.
• The external input to the computer and
external output from the computer will normally
be natural language symbols and characters,
numbers in decimal form.

Numbering Systems
• The set of symbols and rules that we use to represent
quantities, in a numbering system there is an element
q is called base, is the number of distinct symbols
used to represent a quantity.
• Is said to be positional when the value of each digit
depends on its position in the representation is relative
to a base when the value represented by each digit is
obtained by multiplying by the power of the base.
• Decimal: Use 10 symbols, positional and relative to a
base(0—9)
• Binary: Uses 2 symbols (0.1) is positional and relative
to a base
• Octal: Use eight symbols (0 … 7) is on a positional
basis. 1dig = 3dig bina
• Hexadecimal: Use 16 symbols (0 … 9, A. .. F) is on a
positional basis. 1digHexa = 4díg

positive integer
• For instance, to represent the positive integer
one hundred and twenty-five as a decimal
number, we can write
• The subscript 10 denotes the number as a base
10 (decimal) number.
• 12510 = 1*100 + 2*10 + 5*1 = 1*102 + 2*101 +
5*100
• The rightmost digit is multiplied by 100, the next
digit to the left is multiplied by 101, and so on.
• Each digit to the left has a multiplier that is 10
times the previous digit.

• Representing fractions is a simple extension of
this idea.
• 25.43 10 = 2*10 + 5*1 + 4*0.1 + 3*0.01 =
2*101 + 5*100 + 4*10-1+ 3*10-2
• The only pertinent observations here are:
• If there are m digits to the right of the decimal
point, the smallest number that can be
represented is 10-m. For instance if m=4, the
smallest number that can be represented is
0.0001=10-4.
•

Binary Representation of positive integers
• Binary representations of positive can be understood in
the same way as their decimal counterparts. For
example
• 8610 = 1*64 + 0*32 + 1*16 + 0*8 + 1*4 + 1*2 + 0*1
or
8610 = 1* 26 + 0* 25 + 1* 24 + 0* 23 + 1* 22 + 1* 21 + 0*
20
or
8610 = 1010110 2
• The subscript 2 denotes a binary number.
• Each digit in a binary number is called a bit.
• The number 1010110 is represented by 7 bits.
• Any number can be broken down this way, by finding
all of the powers of 2 that add up to the number in
question (in this case 26, 24, 22 and 21).

Decimal
Base-10
Binary
Base-2
Octal
Base-8
Hexadecimal
Base-16
0 0 0 0
1 1 1 1
2 10 2 2
3 11 3 3
4 100 4 4
5 101 5 5
6 110 6 6
7 111 7 7
8 1000 10 8
9 1001 11 9
10 1010 12 A
11 1011 13 B
12 1100 14 C
13 1101 15 D
14 1110 16 E
15 1111 17 F

• . Using hexadecimal makes it very easy to convert
back and forth from binary because each
hexadecimal digit corresponds to exactly 4 bits
• hexadecimal is better suited to the task of
representing binary numbers than is decimal.
• As an example, the number
• CA3= 1100 1010 0011
• (1100= C,1010= A, 0011= 3) ). It is convenient to
write the binary number with spaces after every
fourth bit to make it easier to read.
• 3235=C*256 + A*16 + 3*1
C*(16x16)+ A*(16X1)+ 3*(16X0) or
3235=12*256 + 10*16 + 3*1 =
12*16X16+10*16X1+3*16X0

• bit: A single binary digit, either zero or one.
• byte:8 bits, can represent positive numbers from 0 to
255.
• hexadecimal: A representation of 4 bits by a single
digit 0..9,A..F. In this way a byte can be represented by
two hexadecimal digits
• long word:A long word is usually twice as long as a
word.
• nibble:4 bits, half of a byte.
• octal:A representation of 3 bits by a single digit 0..7.
This is used much less commonly.
• word: Usually 16 bits, or two bytes. But a word can be
almost any size, depending on the application being
considered — 32 and 64 bits are common sizes

Signed Binary Integers
• The simplest way to represent signed binary
integers is ones complement, where the sign of a
binary number is changed by simply toggling each
bit (0’s become 1’s and vice–versa) 0000 0000
ones complement representation is 1111 1111
• To represent an n bit signed binary number the
leftmost bit, has a special significance
• The value of bits in signed and unsigned binary
numbers
• Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
• Unsigned 27= 128 26= 64 2^5= 32 2^4= 16 2^3= 8 2^2= 4 2^1= 2 2^0= 1
• Signed –(27) = –128 26=
• 64 25= 32 24= 16 23= 8 22= 4 21= 2 20= 1

• If Bit 7 is not set the representation of signed
and unsigned numbers is the same.
However, when Bit 7 is set, the number is
always negative.
For this reason Bit 7 is called the sign bit.
Signed numbers are added in the same way as
unsigned numbers, the only difference is in
the way they are interpreted.

two’s complement number
• To form a two’s complement number that is negative
you simply take the corresponding positive number,
invert all the bits, and add 1
• forming the number negative 35 as a two’s
complement integer:
• (35) = (0010 0011)
• invert–> 1101 11002
• add 1–> 1101 11012
• So 1101 1101 is our two’s complement representation
of –35.
• contributions from the individual bits.
• 1101 11012= –128 + 64 + 0 + 16 + 8 + 4 + 0 + 1 = –35.

Positive Binary Fractions
• The representation of unsigned binary fractions proceeds in exactly
the same way as decimal fractions. For example,
•
• 0.625
• =1*0.5 + 0*0.25 + 1*0.125
• = 1* 2–1+ 0* 2–2+ 1* 2–3= 0.101
• Each place to the right of the decimal point represents a negative
power of 2, just as for decimals they represent a negative power of
10.Likewise,if the rearem bits to the right of adecimal,the precision
of the number is 2–m(versus 10–mfor decimal). Though it is
possible to represent numbers greater than one
by having digits to the left of the decimal place we will restrict
ourselves to numbers less than one.
• These are commonly used by Digital Signal Processors.

Signed Binary Fractions
• Signed binary fractions are formed much like
signed integers
• this leftmost bit represents a sign bit just as with
two’s complement integers. If this bit
is set, the number is negative, otherwise the
number is positive.
• There is a terminology for naming the resolution
of signed fractions. If there are m bits to the right
of the decimal point, the number is said to be in
Qm format. For a 16 bit number (15 bits to the
right of the decimal point) this results in Q15
notation.
•

• Signed binary fractions are easily extended to
include all numbers by representing the
number to the left of the decimal point as a
2’s complement integer, and the number to
the right of the decimal point as a positive
fraction.
• Convert 0.100 1001 to decimal .
• Takethebinarynumber01001001(=73),and
divide by 27=128. The answer is
73/128=0.5703125.
• Convert 1.100 1001 to decimal. Take the two’s
complements binary number
• 1100 1001 (=–5510), and divide by 128. The
answer is – 0.4296875.

Representing Fractions in Binary Fixed–point Numbers
• Fixed–point formats are often used in business calculations
• where floating–point with insufficient precision is
unacceptable when dealing with money.
• It is helpful to study it to see how fractions can be stored in
binary.
• A number of bits sufficient for the precision and range
required must be chosen to store the fractional and integer
parts of a number. For example, using a 32–bit format, 16
bits might be used for the integer and 16 for the fraction.
• Examples: integer bits fractional bits
• 0.5 =12= 00000000 00000000. 10000000 00000000
• 1.25 = 114= 00000000 00000001. 01000000 00000000
• 7.375 = 738= 00000000 00000111. 01100000 00000000

Floating–Point Numbers
• In the decimal system, we are familiar with
floating–point numbers of the form: 1.1030402 ×
105
• =1.1030402 × 100000
• = 110304.02
• 1.1030402E5
• 2.3434E–6=2.3434 × 10–6= 2.3434 × 0.000001 =
0.0000023434 The
• advantage of this scheme is that by using the
exponent we can get a much wider range of
numbers,
• even if the number of digits in the significant, or
the “numeric precision”, is much smaller than the
range. Similar binary floating– point formats can
be defined for computers.

Representation of Alphanumeric Data
• 74 unique bit strings are needed to serve as
codes for the entire character set.
• Uppercase letters :26
• Lowercase letters :26
• Digits (0–9) :10
• Special Characters :12
• Total :74
• The two coding schemes most frequently used
for the representation of character information
by computers are:
• ASCII (American Standard Code for Information
Interchange) – 7– bit code.
• EBCDIC (Extended Binary Coded Decimal
Information Code) – 8– bit code.

UNICODE
• Unicode is a computing industry standard for the consistent
representation and handling of text expressed in most of the
world’s writing systems.
• Unicode standard is the Universal character encoding standard,
used for representation of text for Computer Processing.
• Unicode standard provides the capacity to encode all of the
characters used for the written languages of the world.
• The Unicode standards provide information about the character
and their use.
• Unicode Standards are very useful for Computer users who deal
with multilingual text, Business people, Linguists, Researchers,
Scientists, Mathematicians and Technicians.
• Unicode uses a 16 bit encoding that provides code point for more
than 65000 characters (65536).
• Unicode Standards assigns each character a unique numeric value
and name.
• The Unicode standardand ISO10646 Standard provide an extension
n mechanism called UTF–16 that allows for encoding as many as a
million.
• Presently Unicode Standard provide codes for 49194 characters.

REVIEW QUESTIONS
• What is Information and how it is different from Data?
• How information processed. Explain the complete cycle.
• How does the quality of information effect its processing?
State an example to explain.
• What are the characteristics of information?
• What does the value of information indicate? How one can
calculate the value of information.
• Explain the information processing cycle.
• Explain how data & information is represented in computer
memory.
• What are the various coding schemes used in computers?

Questions on Number System
1. Convert 125 from decimal to binary
2. Convert 96 from decimal to binary
3. Convert 10011 from binary to decimal
4. In ‘C’, an unsigned integer is usually 16 bits. What is the largest
number that can be represented by an unsigned integer?
5. Convert 37 to binary, shift it left by one and convert back to
decimal. What is the result?
6. Convert 2000 from decimal to hexadecimal
7. Convert 3C from hexadecimal to decimal
8. Convert 1010 0111 1011 from binary to hexadecimal
9. Convert 7D0 from hexadecimal to binary
10. If you shift a hexadecimal number to the left by one digit, how
many times larger is the resulting number?
11. Convert 1101 1101 from binary to decimal
12. Convert 0010 0010 from binary to decimal
13. Convert –120 from decimal to binary

CYBER SECURITY UNIT 1 PART 1 ppt.pptx

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