Prof. Neeraj Bhargava
Mrs. Shubha Chaturvedi
Department of Computer Science, School of Engineering & System Sciences
MDS University Ajmer, Rajasthan
 There are two basic building blocks of all
Encryption Techniques:
1. SUBSTITUTION
2. TRANSPOSITION.
CLASSICAL
ENCRYPTION
SUBSTITUTION
TRANSPOSTION
PRODUCT CIPHER
A Substitution Technique is one in
which the letters of plaintext are
replaced by other letters or by
numbers or symbols. If the plaintext is
viewed as a sequence of bits, then
substitution involves replacing
plaintext bit patterns with cipher text
bit patterns.
 The substitution cipher always replaces a plain text
symbol to obtain a cipher text symbol whereas
transposition cipher does not change the character
in the plain text when it generates the cipher text it
just rearrange them like anagram
 It hides the message by rearranging the letter order
without altering the actual letter used .
 It applies some kind of permutation function to the
text to produce rearrangement , which can be
reversed if you know the secret to permutation .
 It is Product Cipher is a combination of
substitution and Transposition cipher.
 Product cipher, data encryption scheme in
which the cipher text produced by
encrypting a plaintext document is
subjected to further encryption. By
combining two or more simple transposition
ciphers or substitution ciphers , a more
secure encryption may result.
Q. Differentiate between the types of
classical encryption techniques?

Classical encryption techniques

  • 1.
    Prof. Neeraj Bhargava Mrs.Shubha Chaturvedi Department of Computer Science, School of Engineering & System Sciences MDS University Ajmer, Rajasthan
  • 2.
     There aretwo basic building blocks of all Encryption Techniques: 1. SUBSTITUTION 2. TRANSPOSITION.
  • 3.
  • 4.
    A Substitution Techniqueis one in which the letters of plaintext are replaced by other letters or by numbers or symbols. If the plaintext is viewed as a sequence of bits, then substitution involves replacing plaintext bit patterns with cipher text bit patterns.
  • 5.
     The substitutioncipher always replaces a plain text symbol to obtain a cipher text symbol whereas transposition cipher does not change the character in the plain text when it generates the cipher text it just rearrange them like anagram  It hides the message by rearranging the letter order without altering the actual letter used .  It applies some kind of permutation function to the text to produce rearrangement , which can be reversed if you know the secret to permutation .
  • 6.
     It isProduct Cipher is a combination of substitution and Transposition cipher.  Product cipher, data encryption scheme in which the cipher text produced by encrypting a plaintext document is subjected to further encryption. By combining two or more simple transposition ciphers or substitution ciphers , a more secure encryption may result.
  • 7.
    Q. Differentiate betweenthe types of classical encryption techniques?