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ic:laboratoare:01 [2020/10/07 20:09] acosmin.maria |
ic:laboratoare:01 [2020/10/18 15:55] (current) acosmin.maria |
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| Line 29: | Line 29: | ||
| <file python utils.py> | <file python utils.py> | ||
| import base64 | import base64 | ||
| + | |||
| # CONVERSION FUNCTIONS | # CONVERSION FUNCTIONS | ||
| + | |||
| def _chunks(string, chunk_size): | def _chunks(string, chunk_size): | ||
| for i in range(0, len(string), chunk_size): | for i in range(0, len(string), chunk_size): | ||
| yield string[i:i+chunk_size] | yield string[i:i+chunk_size] | ||
| + | |||
| + | def _hex(x): | ||
| + | return format(x, '02x') | ||
| + | |||
| def hex_2_bin(data): | def hex_2_bin(data): | ||
| return ''.join(f'{int(x, 16):08b}' for x in _chunks(data, 2)) | return ''.join(f'{int(x, 16):08b}' for x in _chunks(data, 2)) | ||
| + | |||
| def str_2_bin(data): | def str_2_bin(data): | ||
| return ''.join(f'{ord(c):08b}' for c in data) | return ''.join(f'{ord(c):08b}' for c in data) | ||
| + | |||
| def bin_2_hex(data): | def bin_2_hex(data): | ||
| return ''.join(f'{int(b, 2):02x}' for b in _chunks(data, 8)) | return ''.join(f'{int(b, 2):02x}' for b in _chunks(data, 8)) | ||
| + | |||
| def str_2_hex(data): | def str_2_hex(data): | ||
| return ''.join(f'{ord(c):02x}' for c in data) | return ''.join(f'{ord(c):02x}' for c in data) | ||
| + | |||
| def bin_2_str(data): | def bin_2_str(data): | ||
| return ''.join(chr(int(b, 2)) for b in _chunks(data, 8)) | return ''.join(chr(int(b, 2)) for b in _chunks(data, 8)) | ||
| + | |||
| def hex_2_str(data): | def hex_2_str(data): | ||
| return ''.join(chr(int(x, 16)) for x in _chunks(data, 2)) | return ''.join(chr(int(x, 16)) for x in _chunks(data, 2)) | ||
| + | |||
| # XOR FUNCTIONS | # XOR FUNCTIONS | ||
| + | |||
| def strxor(a, b): # xor two strings, trims the longer input | def strxor(a, b): # xor two strings, trims the longer input | ||
| return ''.join(chr(ord(x) ^ ord(y)) for (x, y) in zip(a, b)) | return ''.join(chr(ord(x) ^ ord(y)) for (x, y) in zip(a, b)) | ||
| + | |||
| def bitxor(a, b): # xor two bit-strings, trims the longer input | def bitxor(a, b): # xor two bit-strings, trims the longer input | ||
| return ''.join(str(int(x) ^ int(y)) for (x, y) in zip(a, b)) | return ''.join(str(int(x) ^ int(y)) for (x, y) in zip(a, b)) | ||
| + | |||
| def hexxor(a, b): # xor two hex-strings, trims the longer input | def hexxor(a, b): # xor two hex-strings, trims the longer input | ||
| - | return ''.join(hex(int(x, 16) ^ int(y, 16))[2:] for (x, y) in zip(_chunks(a, 2), _chunks(b, 2))) | + | return ''.join(_hex(int(x, 16) ^ int(y, 16)) for (x, y) in zip(_chunks(a, 2), _chunks(b, 2))) |
| + | |||
| # BASE64 FUNCTIONS | # BASE64 FUNCTIONS | ||
| + | |||
| def b64decode(data): | def b64decode(data): | ||
| return bytes_to_string(base64.b64decode(string_to_bytes(data))) | return bytes_to_string(base64.b64decode(string_to_bytes(data))) | ||
| + | |||
| def b64encode(data): | def b64encode(data): | ||
| return bytes_to_string(base64.b64encode(string_to_bytes(data))) | return bytes_to_string(base64.b64encode(string_to_bytes(data))) | ||
| + | |||
| # PYTHON3 'BYTES' FUNCTIONS | # PYTHON3 'BYTES' FUNCTIONS | ||
| + | |||
| def bytes_to_string(bytes_data): | def bytes_to_string(bytes_data): | ||
| return bytes_data.decode() # default utf-8 | return bytes_data.decode() # default utf-8 | ||
| + | |||
| def string_to_bytes(string_data): | def string_to_bytes(string_data): | ||
| return string_data.encode() # default utf-8 | return string_data.encode() # default utf-8 | ||
| Line 248: | Line 251: | ||
| == Hints == | == Hints == | ||
| - | <node tip> | + | <note tip> |
| * What happens when you XOR a character from [a-z] with the character ' ' (spacebar). Check also for [A-Z]. | * What happens when you XOR a character from [a-z] with the character ' ' (spacebar). Check also for [A-Z]. | ||
| * You can't write a perfect algorithm to solve the problem in one shot, you will mostly have to guess. Why? | * You can't write a perfect algorithm to solve the problem in one shot, you will mostly have to guess. Why? | ||
