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I have to create a state array (4x4 matrix of 128bit in total, having each element of one byte) for implementing AES in python, how can I read one byte at a time from an input text file.

bhanu pratap
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  • You can read the lines, join the list into a string, and go through it letter by letter. *Assuming ASCII encoding*, that should be one byte at a time. – ofthegoats Oct 07 '19 at 18:32

1 Answers1

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I'll assume you are using NumPy since you mention 4x4 matrix.

Suppose we have text.txt with "this is a TEST ø´®†˙∆\n" as its contents. We can use the void data type to work with raw data. 

>>> arr = np.fromfile('text.txt', dtype='|V1')
>>> arr
array([b'\x74', b'\x68', b'\x69', b'\x73', b'\x20', b'\x69', b'\x73',
       b'\x20', b'\x61', b'\x20', b'\x54', b'\x45', b'\x53', b'\x54',
       b'\x20', b'\xC3', b'\xB8', b'\xC2', b'\xB4', b'\xC2', b'\xAE',
       b'\xE2', b'\x80', b'\xA0', b'\xCB', b'\x99', b'\xE2', b'\x88',
       b'\x86', b'\x0A'], dtype='|V1')

This results in the same data as, although ASCII is displayed as characters.

>>> with open('text.txt', 'rb') as fp:
...     byte = fp.read()
>>> byte
b'this is a TEST \xc3\xb8\xc2\xb4\xc2\xae\xe2\x80\xa0\xcb\x99\xe2\x88\x86\n'
Matt Eding
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  • thanks for the answer, but please tell me how I can convert the numpy array with raw datatype to its corresponding original type, in other words, how can I get my text file back with state array if possible using numpy. – bhanu pratap Oct 10 '19 at 10:53