114 lines
3.5 KiB
Python
114 lines
3.5 KiB
Python
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from ubinascii import *
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if not "unhexlify" in globals():
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def unhexlify(data):
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if len(data) % 2 != 0:
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raise ValueError("Odd-length string")
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return bytes([ int(data[i:i+2], 16) for i in range(0, len(data), 2) ])
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b2a_hex = hexlify
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a2b_hex = unhexlify
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# ____________________________________________________________
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PAD = '='
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table_a2b_base64 = [
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
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52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1, # Note PAD->-1 here
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-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11,12,13,14,
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15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
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-1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
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41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
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]
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def _transform(n):
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if n == -1:
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return '\xff'
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else:
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return chr(n)
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table_a2b_base64 = ''.join(map(_transform, table_a2b_base64))
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assert len(table_a2b_base64) == 256
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def a2b_base64(ascii):
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"Decode a line of base64 data."
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res = []
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quad_pos = 0
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leftchar = 0
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leftbits = 0
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last_char_was_a_pad = False
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for c in ascii:
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c = chr(c)
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if c == PAD:
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if quad_pos > 2 or (quad_pos == 2 and last_char_was_a_pad):
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break # stop on 'xxx=' or on 'xx=='
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last_char_was_a_pad = True
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else:
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n = ord(table_a2b_base64[ord(c)])
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if n == 0xff:
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continue # ignore strange characters
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#
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# Shift it in on the low end, and see if there's
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# a byte ready for output.
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quad_pos = (quad_pos + 1) & 3
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leftchar = (leftchar << 6) | n
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leftbits += 6
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#
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if leftbits >= 8:
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leftbits -= 8
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res.append((leftchar >> leftbits).to_bytes(1, 'big'))
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leftchar &= ((1 << leftbits) - 1)
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#
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last_char_was_a_pad = False
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else:
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if leftbits != 0:
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raise Exception("Incorrect padding")
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return b''.join(res)
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# ____________________________________________________________
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table_b2a_base64 = (
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
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def b2a_base64(bin):
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"Base64-code line of data."
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newlength = (len(bin) + 2) // 3
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newlength = newlength * 4 + 1
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res = []
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leftchar = 0
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leftbits = 0
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for c in bin:
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# Shift into our buffer, and output any 6bits ready
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leftchar = (leftchar << 8) | c
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leftbits += 8
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res.append(table_b2a_base64[(leftchar >> (leftbits-6)) & 0x3f])
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leftbits -= 6
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if leftbits >= 6:
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res.append(table_b2a_base64[(leftchar >> (leftbits-6)) & 0x3f])
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leftbits -= 6
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#
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if leftbits == 2:
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res.append(table_b2a_base64[(leftchar & 3) << 4])
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res.append(PAD)
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res.append(PAD)
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elif leftbits == 4:
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res.append(table_b2a_base64[(leftchar & 0xf) << 2])
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res.append(PAD)
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res.append('\n')
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return ''.join(res).encode('ascii')
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