把文件下载下来，拖进JEB进行分析，通过onClickTest函数分析，可以知道这里对输入的字符串和一个字符串对比从而进行正确错误提示，很显然需要输入flag，而对比的字符串就是flag。
注意到程序中有两个固定的byte数组：
下面找到计算flag的函数：
v2数组是通过p、q数组异或得到的，v4是v2中的一部分，可以直接将这个函数写个Java程序破解，拿到flag：
public class test {
private static byte[] p;
private static byte[] q;
public static void main(String[] args) {
p = new byte[]{-40, -62, 107, 66, -126, 103, -56, 77, 122, -107, -24, -127, 72, -63, -98, 64, -24, -5, -49, -26, 79, -70, -26, -81, 120, 25, 111, -100, -23, -9, 122, -35, 66, -50, -116, 3, -72, 102, -45, -85, 0, 126, -34, 62, 83, -34, 48, -111, 61, -9, -51, 114, 20, 81, -126, -18, 27, -115, -76, -116, -48, -118, -10, -102, -106, 113, -104, 98, -109, 74, 48, 47, -100, -88, 121, 22, -63, -32, -20, -41, -27, -20, -118, 100, -76, 70, -49, -39, -27, -106, -13, -108, 115, -87, -1, -22, -53, 21, -100, 124, -95, -40, 62, -69, 29, 56, -53, 85, -48, 25, 37, -78, 11, -110, -24, -120, -82, 6, -94, -101};
q = new byte[]{-57, -90, 53, -71, -117, 98, 62, 98, 101, -96, 36, 110, 77, -83, -121, 2, -48, 94, -106, -56, -49, -80, -1, 83, 75, 66, -44, 74, 2, -36, -42, -103, 6, -115, -40, 69, -107, 85, -78, -49, 54, 78, -26, 15, 98, -70, 8, -90, 94, -61, -84, 64, 112, 51, -29, -34, 126, -21, -126, -71, -31, -24, -60, -2, -81, 66, -84, 85, -91, 10, 84, 70, -8, -63, 26, 126, -76, -104, -123, -71, -126, -62, -23, 11, -39, 70, 14, 59, -101, -39, -124, 91, -109, 102, -49, 21, 105, 0, 37, -128, -57, 117, 110, -115, -86, 56, 25, -46, -55, 7, -125, 109, 76, 104, -15, 82, -53, 18, -28, -24};
int len = p.length;
byte v2[] = new byte[120];
for(int i = 0; i < len; i++) {
v2[i] = ((byte)(p[i]^q[i]));
}
int v0, v3 = v2[0];
for(v0 = 0; v2[v3 + v0] != 0; ++v0) {
}
System.out.println(v3 + " " + v0);
byte[] v4 = new byte[v0];
int v1 = 0;
for(v1 = 0; v1 < v0; v1++) {
v4[v1] = v2[v3 + v1];
}
System.out.println(new String(v4));
}
private String i() {
int v1 = 0;
byte[] v2 = new byte[test.p.length];
int v0;
for(v0 = 0; v0 < v2.length; ++v0) {
v2[v0] = ((byte)(test.p[v0] ^ test.q[v0]));
}
int v3 = v2[0];
for(v0 = 0; v2[v3 + v0] != 0; ++v0) {
}
byte[] v4 = new byte[v0];
while(v1 < v0) {
v4[v1] = v2[v3 + v1];
++v1;
}
return new String(v4);
}
}
运行之后顺利拿到flag。