security-hw's Introduction

Security

In this assignment code you can find the way to implement tow cryptosystems (RSA,Keyword columnar) Using python languages so you will be able to enc/decrypt your messages. we worked as a team with @AlherbishLama and @HaneenKhaled1

RSA

Asymmetric encryption algorithm so there is private and public key . we implemented tis algorithm by following these steps:-

ask the user to enter tow prime numbers and validate that the input is prime and int.
compute n and phi
compute the list that contain all possiple e and ask the user to choose from it
compute the d
now we are be able to generate the private and the public key the public key is a pair from (e,n)while the private key is a pair of numbers(d,n)
the user can choose either encrypt or decrypt and passing the plain text to encrypt or decrypt messages
encrypt or decrypt methods will convert the letters into numbers and also will encrypt/decrypt.

Keyword columnar

The key for the columnar transposition cipher is a keyword e.g. GERMAN. The row length that is used is the same as the length of the keyword.

the user will choose keyword we will assign numbers to each letter accoarding th the alphapatic order
build the grid and order the letters inside it
we will take number 1 as a start each letter in the colomn will write it next to each other then we will move to colomn num 2 and so on this is the encryption process
to decrypt we determined the size of the grid and basing the location of the letters .

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