A .gitignore

@@ -0,0 +1,2 @@ 
+.idea
+a.out

A main.cpp

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+#include <fstream>
+
+const char* chars16 = "0123456789ABCDEF";
+
+struct secret {
+    char bytes[16];
+
+    void load(char* file) {
+        FILE* f = fopen(file, "r");
+        fread(secret, 1, 16, f);
+        fclose(f);
+    }
+
+    void save(char* file) {
+        FILE* f = fopen(file, "w");
+        fwrite(secret, 1, 16, f);
+        fclose(f);
+    }
+
+    void generate() {
+        int r, i, j;
+        for (i = 0; i < 16; i += 4) {
+            r = rand();
+            for (j = 0; j < 4; j++) {
+                bytes[i + j] = r & 255;
+                r >>= 8;
+            }
+        }
+    }
+};
+
+stuct otp {
+
+};
+
+int main() {
+    secret s;
+    s.generate();
+    for (int i = 0; i < 16; i++) {
+        printf("%c%c", chars16[s.bytes[i] >> 4], chars16[s.bytes[i] & 15]);
+    }
+}