This code enable decimal base conversion according map length and a different char set.
Example:
- map = ['0','1'] base 2 10 -> 1010
- map = ['a','b'] base 2 10 -> baba
- map = ['a','b','c','d','e','f','g','h','i','j','k','l'] base 12 10 -> k
- map = ['a','b','c','d','e','f','g','h','i','j','k','l'] base 12 100 -> ie
this simple method can be used in web sites to hide a well known decimal sequence like user ids.
Python, 36 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | # Deveploed by Mark Zitnik
# selected map can be change scrambled
map = ['a','b','c','d','e','f','g','h','i','j','k','l','1','H']
map_dict = {}
base = len(map)
# create a bi-directional dict
for item in range(base):
map_dict[item] = map[item]
map_dict[map[item]] = item
def i_to_map_base(num):
if num == 0: return map_dict[0]
base_str = []
while num > 0:
base_str.append(map_dict[ num % base ])
num = num / base
base_str.reverse()
return ''.join(base_str)
def map_base_to_i(str):
x = [a for a in str]
x.reverse()
value = 0
for i in range(len(x)):
item = x[i]
value += (map_dict[item] * pow(base,i))
return value
# test code
for i in range(1000):
str = i_to_map_base(i)
val = map_base_to_i(str)
print 'i[%s] : [%s:%s]' % (i , str , val)
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