How to Reverse Byte-to-Integer Conversion using int.from_bytes() in Python?

Reversing the Bytes-to-Int Conversion

In pursuing encryption/decryption endeavors, converting bytes to integers can be crucial. However, the common issue arises when trying to invert this process. To address this:

int.from_bytes: A Byte-to-Integer Conversion Helper

Python 3.2 and later provide an inbuilt solution: int.from_bytes(bytes, byteorder, *, signed=False). This method takes a bytes-like object or an iterable producing bytes and converts it to an integer.

The byteorder argument specifies the order of bytes in the numeric representation:

• "big" indicates that the most significant byte is at the beginning.
• "little" places the most significant byte at the end.
• Use sys.byteorder for the native byte order of the system.

Additionally, the signed parameter determines whether two's complement is used, enabling negative integer representation.

Example Implementations:

Consider the following examples:

<code class="python">int.from_bytes(b'\x00\x01', "big")    # Result: 1
int.from_bytes(b'\x00\x01', "little")  # Result: 256

int.from_bytes(b'\x00\x10', byteorder="little")  # Result: 4096
int.from_bytes(b'\xfc\x00', byteorder="big", signed=True)  # Result: -1024</code>

By leveraging int.from_bytes, programmers can effortlessly convert byte sequences into integers, a crucial step in various computing tasks.

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