flag_printer_temp

flag_printer/flag_printer.py

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+#!/usr/bin/env python3
+import galois
+import numpy as np
+MOD = 7514777789
+
+points = []
+
+for line in open('encoded.txt', 'r').read().strip().split('\n'):
+    x, y = line.split(' ')
+    points.append((int(x), int(y)))
+
+GF = galois.GF(MOD)
+print(GF.properties)
+
+matrix = []
+solution = []
+for point in points:
+    x, y = point
+    solution.append(GF(y % MOD))
+
+    row = []
+    for i in range(3):
+        row.append(GF((x ** i) % MOD))
+    
+    matrix.append(GF(row))
+
+print('solving')
+open('output.bmp', 'wb').write(bytearray(np.linalg.lstsq(GF(matrix), GF(solution)).tolist()[:-1]))

flag_printer/sol.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+from sage.all import *
+MOD = 7514777789
+
+ring=GF(MOD)
+
+points = []
+for line in open('encoded.txt', 'r').read().strip().split('\n'):
+    x, y = line.split(' ')
+    points.append((int(x), int(y)))
+
+print("building matrices")
+
+solution = []
+M = []
+for point in points:
+    x, y = point
+    solution.append(ring(y % MOD))
+
+    row = []
+    for i in range(3):
+        row.append(pow(x, i, MOD))
+    M.append(row)
+
+print("converting matrices")
+
+solution = vector(solution)
+M = Matrix(M, base_ring=GF(MOD))
+
+print('solving')
+open('output.bmp', 'wb').write(bytearray(M.solve_right(solution).tolist()[:-1]))