## IV. Block Cipher & DES

Before getting started with Block Cipher, digital computer communications based on bits, where 1 byte equals 8 bits. For instance, the word cryptoquantus consist of 13 characters (byte), so it equals to 8x13 = 104 bits . ASCII (American Standard Code for Information Interchange) is an encoding representing each typed character by a number, where … Continue reading IV. Block Cipher & DES

## III. Transposition Cipher

First Transposition Cipher in History It was firstly used by Greeks and Spartans for military secrecy, 15th Century B.C. as Scytale Cipher. A Scytale Cipher is simply a wooden stick around which a strip of leather is wrapped. Sender writes the message along the length of the stick and unwinds the strip, where letters are … Continue reading III. Transposition Cipher

## Introduction to Black Holes

Supermassive Black Hole (SMBH) at the center of M87 (a.k.a Virgo A), April 10th 2019 by Katie Bouman What is a Black Hole ? Briefly, a Black Hole is nothing but an empty space that is a great amount of matter packed into a very small area where the gravitational field of a black hole is so … Continue reading Introduction to Black Holes

## II. Information Entropy & Cryptography (Brute Force and Cryptanalysis)

Brute Force Attack As the name suggests, "Brute Force Attack", the process is based on testing all possible keys until find the correct key. Let's consider that the attacker finds out the correct key after trials. We have 4 keys such as, k_1-(00), k_2-(01), k_3-(10), k_4-(11) where information entropy of the system is 2 bits … Continue reading II. Information Entropy & Cryptography (Brute Force and Cryptanalysis)

## I. Cryptography: 101

Cryptography Terminology Cryptography, the study of encryption and decryption techniques. Cryptanalysis, codebreaking and deciphering ciphertext without the key. Cryptology, the field of cryptography and cryptology. Alice, Bob & Eve Framework Alice sends a message to Bob and Eve (stands for eaves dropper) wants to get the message. Here; there are, classical (e.g. Caesar cipher) and modern … Continue reading I. Cryptography: 101