A Cipher can also be called as an Algorithm about how to perform encryption and
Decryption.
There are multiple methods how it can be done few of
them are
Substitution – This uses different letter for a
particular letter. meaning.
'A' could be 'X'
(A is Cipherd to be X)
Poly alphabetic – This uses multiple letter for a particular letter (alphabet)
Like for Example
‘A’ – ‘DCE’
(A is cipher and is DCE)
Transposition – This rearranges the letters in different form
Example - “This is Secret”
T S S R
H I E E
I S C T
(It's just jumbling of words)
What’s keys then?
Keys are somethings that
are used to decry-pt these cipher Encryption.Which has be to know to both the Receiver and the Provider of the packet.
A one-time pad (OTP) is a good example of a key that is only used
once.
if we want to encrypt a 32-bit message, we use a 32-bit key, also called the
pad, which is
used one time only. The key in this case is the one-time use pad. The pad must
also be known by the receiver if he wants to
decrypt the message.