Caesarts Cipher encryption algorithm assistance

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Andrew Marttini
Andrew Marttini 2019-7-14
评论： Yifan He 2022-7-28
Caesar's cypher is the simplest encryption algorithm. It adds a fixed value to the ASCII (unicode) value of each character of a text. In other words, it shifts the characters. Decrypting a text is simply shifting it back by the same amount, that is, it substract the same value from the characters. Write a function called caesar that accepts two arguments: the first is the character vector to be encrypted, while the second is the shift amount. The function returns the output argument coded, the encrypted text. The function needs to work with all the visible ASCII characters from space to ~. The ASCII codes of these are 32 through 126. If the shifted code goes outside of this range, it should wrap around. For example, if we shift ~ by 1, the result should be space. If we shift space by -1, the result should be ~.
Here are a few things you may want to try with MATLAB before starting on this assignment:
double(' ')
ans =
32
double('~')
ans =
126
char([65 66 67])
ans =
'ABC'
' ' : '~'
ans =
' !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'
And here are a few example runs:
caesar('ABCD',1)
ans =
'BCDE'
caesar('xyz ~',1)
ans =
'yz{! '
caesar('xyz ~',-1)
ans =
'wxy~}'
Code to Call your Function:
coded = caesar('ABCD', 3)
decoded = caesar(coded, -3)
wrap = caesar('1234', 96)
back = caesar(wrap, -96)
Hi there, I am having trouble with the caesars cypher question for week 8 homework assignments and I was wondering if I could get some help with the code that I have so far. Here is what I have, any help would be appreciated.
function coded = caesar(v,n)
v = char(32:126)
secret = v + 2
mod(v,126)
coded = char(mod(v,126))
end
ps. I feel embarrased posting this I am trying to figure it out but it is very difficult for me.
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显示 18更早的评论
evan muas
evan muas 2019-12-29
A link to my answer on stackexchange
https://stackoverflow.com/a/59522032/10810614

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回答（4 个）

Akhil Thomas
Akhil Thomas 2020-5-16
function
y = caesar2(ch, key)
v = ' ' : '~';
[~, loc] = ismember(ch, v);
v2 = circshift(v, -key);
y = v2(loc);
end
Akhil Thomas
Akhil Thomas 2020-5-16
function txt = caesar(txt,key)
txt = double(txt) + key;
first = double(' ');
last = double('~');
% use mod to shift the characters - notice the + 1
% this is a common error and results in shifts
% being off by 1
txt = char(mod(txt - first,last - first + 1) + first);
end
Shaun Olisagu
Shaun Olisagu 2020-7-27
function coded = caesar(text, amount)
new_text = double(text)
text_shift = new_text + amount
coded = char(mod(text_shift,(32:126,32)))
end
Pls help. I've been on this for quite a long time now
Yifan He
Yifan He 2022-7-28
编辑：Walter Roberson 2022-7-28
function coded = caesar(v,s)
x = double(v);
y = x + s;
if y >= 32
n = fix((y-32)/95);
else
n = fix((y-126)/95);
end
z = y - 95*n;
coded = char(z);
  2 个评论
Yifan He
Yifan He 2022-7-28
It still make sense. This problem is a step function in mathematics, actually. z=f(y)=y-95n (32+95n ≤ y ≤ 126+95n,n∈Z)

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