How to solve the problem?
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Darsana P M
le 12 Avr 2018
Commenté : Darsana P M
le 16 Avr 2018
I have a dicom image,I of size :
size(I)
ans =
716 1000 3
From this I took first 64 bits,like I(1:16),I(17:32),I(33:48),I(49:64) and did the encryption operation. So before sending it I would like to get back the remaining bits and thus get back the image?
I hope the question is clear.Here I took Ist rows upto 64. This is stored in suppose a variable A.How to get the remaining bits, so that if store the variable in B. So that after decryption of A,I can concatenate with B and get back the final image.
Can somebody help me out to get this?
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Walter Roberson
le 14 Avr 2018
Those are not the first 64 bits. The first 64 bits are probably I(1:4) or I(1:8)
However AES-GCM of a dicom image needs the first 64 bits of the dicom file itself, not of the image stored in the file.
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Walter Roberson
le 15 Avr 2018
A1bits = reshape((dec2bin(typecast(A1, 'uint8'), 8) - '0').', 1, []);
This will be a row vector. Once you have done this up to A4 then you can do
[A1bits, A2bits, A3bits, A4bits]
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Walter Roberson
le 15 Avr 2018
[YourMatrix(1,65:end), reshape(YourMatrix(2:end,:).', 1, [])]
However, I do not understand why you are taking the first 64 numbers or elements of the first row when you want the first 64 bits. Your array contains double precision precision numbers, so your elements are 64 bits each, so the first 64 of the first row would be 64 elements * 64 bits per element = 4096 bits. You are only producing a 64 bit hash, so you are losing 63*64 = 4032 bit positions in your output.
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