66 lines
2.8 KiB
Python
66 lines
2.8 KiB
Python
import sys
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def java_string_hashcode(s): # The hashCode function in java.
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h = 0
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for c in s:
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h = (31 * h + ord(c)) & 0xFFFFFFFF
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return ((h + 0x80000000) & 0xFFFFFFFF) - 0x80000000
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def isFlag(str):
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return java_string_hashcode(str) == 1471587914 and java_string_hashcode(str.lower) == 1472541258 # The function from the CTF.
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def main():
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sum=0
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max1 = pow(31, 4) * 122 # Max option of alphanumeric characters.
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min1 = pow(31, 4) * 48 # Min option of alphanumeric characters.
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max2 = pow(31, 3) * 122
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min2 = pow(31, 3) * 48
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max3 = pow(31, 2) * 122
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min3 = pow(31, 2) * 48
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max4 = pow(31, 1) * 122
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min4 = pow(31, 1) * 48
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max5 = 122
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min5 = 48
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list=[] # Make a list of alphanumeric characters.
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for i in range (48,58):
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list.append(i)
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for i in range (65,91):
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list.append(i)
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for i in range(97, 123):
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list.append(i)
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for i0 in list:
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x0 = pow(31, 5) * i0
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if (x0 + max1 + max2 + max3 + max4 + max5 >= 1471587914 and x0 + min1 + min2 + min3 + min4 + min5 <= 1472541258):
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print("flag[0] =", i0)
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for i1 in list:
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x1 = pow(31, 4) * i1
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if (x0 + x1 + max2 + max3 + max4 + max5 >= 1471587914 and x0 + x1 + min2 + min3 + min4 + min5 <= 1472541258):
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print("flag[1] = ", i1)
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for i2 in list:
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x2 = pow(31, 3) * i2
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if (x0 + x1 + x2 + max3 + max4 + max5 >= 1471587914 and x0 + x1 + x2 + min3 + min4 + min5 <= 1472541258):
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print("flag[2] = ", i2)
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for i3 in list:
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x3 = pow(31, 2) * i3
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if (x0 + x1 + x2 + x3 + max4 + max5 >= 1471587914 and x0 + x1 + x2 + x3 + min4 + min5 <= 1472541258):
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print("flag[3] = ", i3)
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for i4 in list:
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x4 = pow(31, 1) * i4
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if (x0 + x1 + x2 + x3 + x4 + max5 >= 1471587914 and x0 + x1 + x2 + x3 + x4 + min5 <= 1472541258):
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print("flag[4] = ", i4)
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for i5 in list:
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x5 = i5
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if (x0 + x1 + x2 + x3 + x4 + x5 == 1471587914 ):
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flag = ""
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flag += chr(i0) + chr(i1) + chr(i2) + chr(i3) + chr(i4) + chr(i5)
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if(java_string_hashcode(flag.lower())==1472541258): # Check for the lowercase condition.
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print("The flag is:", flag)
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sys.exit()
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main()
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