codes & ciphers Flashcards

1
Q

utilizes a set of symbols to represent an object

A

code
Ex: “A” can be replaced by a string of “0’s” and “1’s”, say 00101

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2
Q

a scheme to conceal information by switching letters or representing them with other symbols

A

ciphers

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3
Q

It is used heavily in communication and data transmission.

A

ciphers

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4
Q

briefly explain cryptology

A

plain text —-> cipher text (cryptography)

cipher text —-> plain text (cryptanalysis)

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5
Q

define coding theory

A

the study of methods for efficient and accurate transfer of information

detect and correcting transmission errors

deals with the design of error-correcting codes for the reliable transmission of information across noisy channels

make use of classical and modern algebraic techniques (finite fields, group theory and polynomial algebra)

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6
Q

ISBN

A

international standard book number

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7
Q

it regulates and keep track of various publications in different
parts of the world

A

ISBN international standard book number

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8
Q

how many digit code are there in the
ISBN
UPC

A

ISBN:
10 digit code to 13 digit code. expanded in 2007

UPC:
12 digit code

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9
Q

who takes charge of the ISBN registration, allocation, and designation for Filipino publishers
and authors

A

the national library of the Philippines (NLP)

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10
Q

in ISBN ,
the first 3 digit =
the fourth digit =
remaining digits except the last =
last digit =

A

the first 3 digit = 978 or 979
the fourth digit = country code
remaining digits except the last = identify the author and the title of the book
last digit = check digit

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11
Q

UPC

A

universal product code

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12
Q

in UPC,
the last digit =

A

the last digit = check digit

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13
Q

in Philippines, what are the dominant cards in the market
and how many digit numbers

A

Visa
Mastercard

normally having 16 digit numbers except for some Visa cards that have 13 digits only

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14
Q

define binary codes

A

it refers to a string of 0’s and 1’s

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15
Q

in binary codes, define bit and byte

A

bit: each character in the string
byte: a series of 8 bits

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16
Q

each key in the keyboard of a computer corresponds to a binary code of at least how many bits

A

5

17
Q

how are computers are able to to translate letters and symbols into binary codes

A

using the American Standard Code for Information Interchange (ASCII codes)

18
Q

define hamming code
and it is introduced by

A

a scheme for error correction
introduced by R. W. Hamming

19
Q

hamming code uses what redundant bit

A

parity bit (aka check bit)
it is either ‘even’ or ‘odd’ depending on whether there is an even or odd no. of 1’s

19
Q

why does coded messages tend to be very prone to distortion when being transmitted to available medium

A

because of the presence of some environmental interference or unforeseen defects in the transmission medium

19
Q

in hamming codes, what happens if there is any changes that may occur in a message that may alter its original meaning

A

error

19
Q

define:
cryptography -
encryption -
decryption -

A

cryptography - process of converting data ort info into codes, primarily for the purpose of keeping it secured. it involves encryption and decryption

encryption - converts a message into meaningless and usually unreadable formats that only the intended recipient can understand

decryption - process of recovering the encrypted information

encryption is like locking a message in a box with a special key, and decryption is like using the same key to unlock the box and retrieve the original message. Cryptography ensures that only authorized parties with the correct key can access the sensitive information, while preventing unauthorized access or eavesdropping

19
Q

it is a process by which information is shared among individuals

A

communication

20
Q

what is shift cipher

A

it uses the natural order of the letters on the english alphabet

goal: replace the letters of a given message by another letter which is at some fixed number of positions according to the natural order of the letters

21
Q

formula of shift cipher

A

C = (P + K) mod 26
P - original position of a letter in the given message
C - shifted position (code letter)
K - constant that determines the fixed number of shift positions

22
Q

what is affine cipher

A