Problem 58299. Encrypt a message with the square root of 2

Created by ChrisR

Solve Later

Suppose you want to encrypt the word ‘TWIN’. The ASCII codes for the four letters are 84, 87, 73, and 78. If you consider the fractional part of the square root of 2 as a string 
4142135623730950488016887242096980785696718753769480731766797379907324784…
then those ASCII codes are found at positions 72, 24, 11, and 35. 
Those ASCII codes can be found in other positions in the fractional part of the square of 2. So to add a layer of complexity to the code, choose one of those positions randomly.
Write a function to encrypt a message in this way. Make sure to convert the string to all uppercase before encrypting. A string with the fractional part of the square root of 2 will be set as a global variable, and a seed will be passed to the function to be used in the command rng(seed).

Solve

Solution Stats

26 Solutions
3 Solvers

Last Solution submitted on Mar 23, 2024

Last 200 Solutions

Problem Comments

4 Comments

4 Comments

Show 1 older comment

David Hill on 18 May 2023

How is the global variable provided? Is the solver supposed to provide the global variable and to how many digits? Are you randomly selecting each letter by letter?

Christian Schröder on 18 May 2023

@David The global variable is provided by the test suite.

David Hill on 18 May 2023

@Christian
I don't see how the global variable is provided. Went I run the global variable is empty.

ChrisR on 18 May 2023

David, try it now. The first "test" should be

global sqrt2str
s = webread('https://apod.nasa.gov/htmltest/gifcity/sqrt2.1mil');
sqrt2str = s(1230:1013886);
sqrt2str(strfind(sqrt2str,newline))='';

It was in the test suite, but it didn't appear on Cody till I put '%%' ahead of it.

Solution Comments

Show comments

Problem Recent Solvers3

Problem Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 58299. Encrypt a message with the square root of 2

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers3

Suggested Problems

More from this Author291

Problem Tags

Community Treasure Hunt

Problem 58299. Encrypt a message with the square root of 2

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers3

Suggested Problems

More from this Author291

Problem Tags

Community Treasure Hunt

Players