one time pad plus randstream

Question

Mi 2023-1-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1897630-one-time-pad-plus-randstream

评论： Les Beckham 2023-1-23

采纳的回答： Les Beckham

在 MATLAB Online 中打开

Hello Guys,

I need help for this question asap.

Implement a version of the character based One-Time Pad, that utilizes a random number generator chosen through RandStream.

clc;
clear all;
close all;
alph=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'];
b1=0:25;
keyword='famt';
code='ratn';
disp(keyword);
famt
disp(code);
ratn
for ii=1:length(keyword)
    for jj=1:length(alph)
        if keyword(ii)==alph(jj)
            w1(ii)=b1(jj);
        end
        if code(ii)==alph(jj)
            c1(ii)=b1(jj);
        end
    end
end
ncode=w1+c1;
for ii=1:length(ncode)
    if(ncode(ii)>25)
        ncode(ii)=ncode(ii)-26;
    else
        continue
    end
end
display(ncode);
ncode = 1×4
    22     0     5     6
for ii=1:length(ncode)
    for jj=1:length(b1)
        if ncode(ii)==b1(jj)
            finalcode(ii)=alph(jj);
        else
            continue
        end
    end
end
disp(finalcode);
wafg

7 个评论
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Les Beckham 2023-1-20

You need to get clarification on what portion of the algorithm is supposed to be randomized. Perhaps the code string is supposed to be randomly generated? Until that is clarified, there isn't really anything else we can do to help with this.

Mi 2023-1-20

if the code string is supposed to be randomly generated, then can you help me out with a code for this?

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Answer 1

Les Beckham 2023-1-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1897630-one-time-pad-plus-randstream#answer_1153085

在 MATLAB Online 中打开

Assuming that the random part of the algorithm is generating the code character vector as you said in one of your comments, something like this should do what you want.

Note that this is using RandStream as requested. It could be more easily and more simply done using randi directly without using RandStream.

s = RandStream('dsfmt19937'); % << arbitrarily chosen generator type; change as you wish (see doc link above)
r = randi(s, 26, [1 4]); % 4 integers between 1 and 26 using stream s
code = char(r + 'a'); % convert to letters of the alphabet 
% Then use the simplified one-time pad algorithm I showed in my comment above
keyword='famt';
w1 = double(keyword - 'a');
c1 = double(code - 'a');
ncode = mod(w1+c1, 26)
ncode = 1×4
     6     6    20     3
finalcode = char(ncode + 'a')
finalcode = 'ggud'