Increment Nonce by any fixed value in loop

2019 6 24
2 个回答
回答已采纳
更新时间：2019 6 26
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0 个投票

I have the nonce value in hex. Let say:
nonce = {'00' '11' '22' '33' '44' '55'};
I need to add any fixed value 'x'(hex) to this value in loop and need to save every new value.
I was doing this like:
nonce = {'00' '11' '22' '33' '44' '55'};
for i=1:5
nonce(i) = nonce + 01;
i = i+1;
end
But I am not acheiving what I need.

1 个评论
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Jan
Jan 2019-6-25
Please mention, what you expect as output. Having only not running code does not clarify, what you want to achieve.
Your code contains some bugs:
for i=1:5
nonce(i) = nonce + 01;
% Here on the left side there is a scalar cell element, and on
% the right you try to add 01 (which is the same as 1) to a
% cell vector.
i = i+1; % i is iterated by the FOR loop already
% so do not increase it manually
end

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 采纳的回答

Alex Mcaulley
Alex Mcaulley 2019-6-24

0 个投票

Using a loop:
nonce = {'00' '11' '22' '33' '44' '55'};
x = '01';
for i = 1:numel(nonce)
nonce{i} = dec2hex(hex2dec(nonce{i}) + hex2dec(x),2);
end
Or using cellfun:
nonce = {'00' '11' '22' '33' '44' '55'};
x = '01';
nonce = cellfun(@(y) dec2hex(hex2dec(y) + hex2dec(x),2),nonce,'uni',0);

3 个评论
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Zeeshan Abbas
Zeeshan Abbas 2019-6-25
Thank you but it's giving me: nonce = {'01' '12' '23' '34' '45' '56'}
I need it to be: nonce = {'00' '11' '22' '33' '44' '56'}; just need to increament the whole value by 1, not every element. We can increament it from deecimal value as well and then at last convert it into hex. But I need to increment the value 5-times and need to save every value.
The ultimate usage is to use this as a nonce/counter value in CTR mode block cipher to create bit stream.
Alex Mcaulley
Alex Mcaulley 2019-6-25
Well, then an option is:
nonce = {'00' '11' '22' '33' '44' '55'};
x = '01';
a = strcat(nonce{:});
for i = 2:6
a(i,:) = dec2hex(hex2dec(a(i-1,:)) + hex2dec(x),12);
end
nonce = mat2cell(a,ones(6,1),2*ones(6,1))
nonce =
6×6 cell array
'00' '11' '22' '33' '44' '55'
'00' '11' '22' '33' '44' '56'
'00' '11' '22' '33' '44' '57'
'00' '11' '22' '33' '44' '58'
'00' '11' '22' '33' '44' '59'
'00' '11' '22' '33' '44' '5A'
At the end of the code, each row of nonce corresponds with the value in each iteration.
Zeeshan Abbas
Zeeshan Abbas 2019-6-26
Thank you very much. It's giving what I asked, so I am accepting. Although it don't worked for me in that scenario in which I was seeking this.

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更多回答（1 个）

Jan
Jan 2019-6-25
编辑：Jan 2019-6-25

0 个投票

nonce = {'00' '11' '22' '33' '44' '55'};
toAdd = hex2dec('01');
for k = 1:5
nonce{k} = dec2hex(hex2dec(nonce{k}) + toAdd);
end
It might be easier to work with a double vector, if you want to perform calculations. Then hex strings are rather inefficient.

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