79 lines
2.7 KiB
Python
Executable File
79 lines
2.7 KiB
Python
Executable File
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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# https://www.reddit.com/r/SwitchHacks/comments/f7psrk/anatomy_of_an_eshop_card_code/
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CHARSET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
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def safe2real(code: str) -> str:
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"""Converts a code with unambiguous characters to the real code"""
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code = code.upper()
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code_first = code[0]
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if code_first != 'A':
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code = code.replace('V', 'A') # A might be confused with 4
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code = code.replace('W', 'E') # E might be confused with 3
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code = code.replace('X', 'I') # I might be confused with 1
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code = code.replace('Y', 'O') # O might be confused with 0
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return code
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def real2safe(code: str) -> str:
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"""Converts an actual code to a representation with unambiguous characters"""
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code_first = code[0]
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code = code.upper()
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if code_first != 'A':
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code = code.replace('A', 'V') # A might be confused with 4
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code = code.replace('E', 'W') # E might be confused with 3
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code = code.replace('I', 'X') # I might be confused with 1
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code = code.replace('O', 'Y') # O might be confused with 0
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code = code_first + code[1:]
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return code
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def generate_checksum(base_code, base = 30):
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if len(base_code) != 15:
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raise RuntimeError("Bad argument to checksum")
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# https://www.reddit.com/r/SwitchHacks/comments/f7psrk/anatomy_of_an_eshop_card_code/fijt5d4/
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cksum = sum(int(c, base) for c in base_code) % base
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return CHARSET[cksum]
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def validate(code):
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if len(code) != 16: return False
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# Make uppercase if necessary, then change X and Y back to their base 33 equivalents
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unmangled_code = safe2real(code)
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theirs = unmangled_code[15]
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code_type = get_type(code)
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base = 33 if code_type == '_A_' else 30
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mine = generate_checksum(unmangled_code[0:15], base)
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return theirs == mine
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def parse(code):
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serial = None
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external_validator = None
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code_type = get_type(code)
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unmangled_code = safe2real(code)
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if code_type == 'NUM':
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serial = int(code[0:8])
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external_validator = int(code[8:])
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elif code_type == '_A_':
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serial = int(unmangled_code[1:8], 33)
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external_validator = int(unmangled_code[8:15], 33)
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elif code_type == '_B_' or code_type == '_C_':
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serial = int(unmangled_code[1:8], 30)
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external_validator = int(unmangled_code[8:15], 30)
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else:
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print(" unknown card generation '%s'" % code[0])
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return
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print(" ser#: {:010d} / Ext. validator: {:010d}".format(serial, external_validator))
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def get_type(code: str) -> str:
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if code[0].isnumeric():
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return 'NUM'
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elif code[0] == 'A':
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return '_A_'
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elif code[0] == 'B':
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return '_B_'
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elif code[0] == 'C':
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return '_C_'
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else:
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return 'UNK'
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