Encryption and Decryption using Substitution Algorithm

1. Cryptography
By:-
Neeraj Mali(PB10)
Samyak Sethiya(PB18)

2. •Cryptography is the science and art of
transforming messages to make them
secure and immune to attack.

3. Origin of Cryptography:
• The first known evidence of cryptography can be traced to the
use of ‘hieroglyph’. Some 4000 years ago, the Egyptians used
to communicate by messages written in hieroglyph.
• The most widely known rotor cipher device is the German
Enigma machine used during World War II,
of which there were a number of variants.
• the Zimmermann Telegram triggered the
United States' entry into World War I.

4. • A Purpose of cryptography:
The main purpose of cryptography is to
defend the transmitted information and it
plays an important role in the following:
• Authentication
• Data confidentiality
• Data integrity
• Non-repudiation

5. How Encryption works:

6. How Does a Substitution algorithm
works:
Substitution Cipher
Method of encryption by which units of plaintext
are replaced with cipher text, according to a fixed
system; the “units” may be single letters (the
most common), pairs of letters, triplets of letters,
mixtures of the above, and so forth.

7. • Cryptography is an actively developed library
that provides cryptographic recipes and
primitives. It supports Python 2.6-2.7 and
Python 3.3+.
• cryptography is divided into two layers of recipes
and hazardous materials (hazmat). The recipes
layer provides a simple API for proper symmetric
encryption and the hazmat layer provides low-
level cryptographic primitives.
Lib:

8. Types:
• Secret Key Cryptography (SKC): Uses a single key for
both encryption and decryption; also called
symmetric encryption. Primarily used for privacy and
confidentiality.
• Public Key Cryptography (PKC): Uses one key for
encryption and another for decryption; also called
asymmetric encryption. Primarily used for
authentication, non-repudiation, and key exchange.
• Hash Functions: Uses a mathematical transformation
to irreversibly "encrypt" information, providing a
digital fingerprint. Primarily used for message
integrity.

10. Applications:
• Authentication/Digital Signatures
• Time Stamping
• Electronic Money
• Disk Encryption
• Secure Network Communications

11. References:
• https://www.garykessler.net/library/crypto.html
• https://intellipaat.com/blog/tutorial/ethical-hacking-cyber-
security-tutorial/encryption-techniques/
• https://www.youtube.com/watch?v=9-Yw434IbVM
• https://en.wikipedia.org/wiki/Cryptography