Codes and Cryptography 2 Flashcards
Sender of the message
Source
Recipient of the
message.
Receiver
The process of
turning thoughts into
communication.
Encoding
The process of
turning communication into
thoughts.
Decoding
Reply or response to
the message.
Feedback
Content of
communication.
Message
Vehicle through which
communication travels.
Channel
a symbolic way to
represent information
Code
Three areas of coding
Data compression
Error-correcting codes
Cryptography
the process of reducing the
amount of data needed for the
storage or transmission of a
given piece of information, by the
use of encoding techniques
Data compression
are algorithms,
mathematical formulas used to
compress and decompress files.
CODECs
CODECs for data
PKZIP
CODECs for still images
JPEG,GIF,PNG
CODECs for audio
MP3, MP4, AAC
CODECs for video
Cinepak, MPEG-2, H.264, VP8
Two types of Compression Techniques
Lossless Compression
Lossy Compression
No data lost when file is reduced
Lossless Compression
used in image, text file and also
use for executable file; Examples: WinZip, 7z, GIF & PNG.
Lossless Compression
Small losses in data is tolerable.
Lossy Compression
Used in video and audio; Examples: JPEG, MPE
Lossy Compression
a condition when the
transmitted information is not
the same as the information
sent.
Error
when it
detects an error it tries to put
data back to how it should have
been
Error correction
the general
term for correction and error
detection systems.
Error control
Types of error detection
Parity Checking
Cyclic Redundancy Check
Longitudinal Redundancy Check
Check Sum
One extra bit is sent along with
the original data bits.
Parity Check
help to check if any
error occurred in the data during
the transmission.
Parity bits
used to verify errors on
identification numbers; A single number generated
using the other characters from
the identification number.
Check Digits
the bar code which is the
identification number of a retail
item
Universal Product Code
Code printed on retail product
packaging to aid in identifying a
particular item/product
Bar codes
Series of thick and thin lines with
numbers at the bottom printed
on the item.
Bar codes
Consists of 12 digits; the first 11
characters specify the source of
the item and the product
number.
UPC
Who used Ceasar Cipher
Julius Ceasar teh
How many alphabet positions does the Ceasar Cipher shifts
3
What’s the modular arithmetic of Ceasar Cipher
f(p) = (m + 3 mod 26)
Three types of Cryptography
- Secret Key Cryptography
(Symmetric) - Public Key Cryptography
(Assymetric) - Message Digest (Hashing)
