Encoding
Encoding is
converting one data type to another data type using any method. Why we convert
one data type to another type. There are two reasons for this.
We know our computers can store their memory only bits. That means 1
& 0 in binary language. So every data what we store in the computer memory
is stored in after converting binary data. Best example is ASCII, Unicode.
When
transmitting the data from one place to another, data have been encoded because
of the safety of data and system. Best example for this transmitting the data
through HTTP we encode the data according to the base64 algorithm. Encode the
data using this method English letters are changed to numbers and there are
special two characters. In the internet every URLs are encoded.
Best
advantage of encoding when using data between two systems is these two system
can understand the data. Not to be stolen by anybody or the change of data is
not expected.
To decode
the encoded data using an algorithm, we use famous algorithm to encode data. So
if anyone know the algorithm can decode the encoded data.
Encrypting
Encrypting
belongs to cryptography. That means when data are transmitted or stored, the
data is changed so that anybody cannot steel them.
Example for Encrypted string
^#s!MF#:5_(A!R5-(X_
These
type of encrypted data can’t be understood.
Encrypted
data using this method are called cipher-text. Not encrypted data is called as
plain-text.
We
use key to encrypt data.
Using this key encrypting
methods can divide into two ways.
- Symmetric key encryption
In this method a key is used to encrypt the data. If anyone wants
decry-pt these data he should use the same key.
- Asymmetric Cryptography(public-key cryptography)
In this method two keys are used and those are public
key and private key. Anyone can watch this public key. But private key is
confidential. We use public key for data encrypt. One who receive the cipher
text use private key to decry-pt. But can’t decry-pt using public key.
Nowadays important
web sites use SSL technology. This SSL is Public-key cryptography technology.
This is a small
algorithm to encrypt and decry-pt. I use this for Transposition cipher method
and python language.
In Transposition chipper method
We think plaintext is – thisis
Key – mymainkey
First we take the
key and remove the characters which come more than once.
m y a i n k e
According to the
length of the key the alphabet is written in sections. The characters in the key is not written
again.
m y a I n k e
b c d f g h l
o p q r s t u
v w x y z
Now characters are
written in the key according to the alphabetical order from the top to the
bottom.
a d q x e l u i f r y k h t m b o v n g s z y c p
w
a b c d e f g h i
j k l m n o p q r s t u v w x
y z
Instead of the
characters of the alphabet written below, characters of the upper line can be
used to build the cipher-text.
n m h u h u
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