Update README.md

Author: josgard94

README.md

@@ -1,2 +1,17 @@
 # CaesarCipher
-In this project I develop a plaintext file encryption using shift encryption or César encryption, this project was implemented in the Python programming language.
+
+	Author: Edgard Diaz
+	Date: 17th march 2020	
+	
+	In this project I develop a plaintext file encryption using shift encryption or César encryption, this project was implemented in   the Python programming language.
+
+	To perform the Caesar cipher, the alphabet can be represented by modular arithmetic 
+	by first transforming the letters into numbers, as shown below, A → 0, B → 1, ..., Z → 25. 
+	Based on this, you can perform encryption of a letter x using an n-letter offset, 
+	and such encryption can be described mathematically as (1):
+
+						E_n(x)  = (x + n) % 61					(1)
+
+	The decryption process is performed in a similar way using (2)
+
+						D_n(x) = (x - n) % 61