Python：使用base64解码bin

Question

如果我有二进制字符串，可以说str = "010100011010101001001101100101100110101" ，它是由其他字符串的base64版本编码的，如何解码该字符串？

Answer 1

It would have been great if your example string is actually something meaningful rather than something made up which makes this question rather unclear, but I will try my best here to figure out what you might have meant in the most verbose manner possible.

Assuming your actual input is a str that looks like this:

s = '101100101010011010000100011000001011010010110000100111000110000'

You can get the hexadecimal form of this by casting it to int using the base keyword argument

>>> i = int(s, base=2)  # 6436561067884170800

Then turn it back into a string by formatting it like so:

>>> h = '%x' % i  # '595342305a584e30'

Then use the binascii.a2b_hex function on the hexadecimal string to get the raw bytes:

>>> b64 = binascii.a2b_hex(h)  # b'YSB0ZXN0'

If it is some valid base 64 encoded stream of bytes, you may then use base64.b64decode on that to get the actual bytes

>>> r = base64.b64decode(b64)  # b'a test'

To turn that into a string, apply the correct codec to it (ie use bytes.encode ).

Finally, if you cared to know how I generated that input, this is all the above, reversed into a single one-line function:

>>> '{0:b}'.format(int(binascii.b2a_hex(base64.b64encode(b'a test')), base=16))
'101100101010011010000100011000001011010010110000100111000110000'