Topic1 substitution transposition-techniques

Substitution and transposition techniques

1.   Substitution and transposition techniques Name: Md Fazle Rabbi ID:16CSE057

2. Contents Cryptography Vocabulary Encryption & Decryption  Substitution Technique Transmission Technique 1

3. What is Cryptography ? Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient. 2

4. Vocabulary 3 plaintext - the original message Cipher text - the coded message cipher - algorithm for transforming plaintext to ciphertext key - info used in cipher known only to sender/receiver encipher (encrypt) - converting plaintext to ciphertext decipher (decrypt) - recovering ciphertext from plaintext cryptography - study of encryption principles/methods cryptanalysis (codebreaking) - the study of principles/ methods of deciphering ciphertext without knowing key cryptology - the field of both cryptography and cryptanalysis

5. Cryptography Basic 4

6. Types of Cryptography 5

7. Continue… 6

8. Asymmetric Cryptography 6

9. Both  Substitution cipher technique  and  Transposition cipher technique  are the types of Traditional cipher  which are used to convert the plain text into cipher text. Substitution Cipher Technique: In Substitution Cipher Technique plain text characters are replaced with other characters, numbers and symbols as well as in substitution Cipher Technique, character’s identity is changed while its position remains unchanged. Transposition Cipher Technique: Transposition Cipher Technique rearranges the position of the plain text’s characters. In transposition Cipher Technique, The position of the character is changed but character’s identity is not changed. 7

10. Types of Substitution Cipher Technique: 8  Caesar Cipher  Monoalphabetic Ciphers  Playfair Cipher  Hill Cipher  Polyalphabetic Ciphers  Vigenère Cipher  Autokey Cipher  Vernam Ciphe

11. Transposition Techniques Rail Fence Cipher. Row Transposition Cipher. 9

12. Row Transposition Cipher. 9

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