2018/11/26-AXCTF-安卓

import com.sun.org.apache.xml.internal.security.utils.Base64;
public class Main{
    public static void main(String[] args) {
        String flag;
        byte[] str1 = new byte[100];
        String str2;

        try {
            str1 = Base64.decode("w73DrcK2GcKkw7nCv8KgwpbDrMOdw7TDqFTDjRAcJA==");
        } catch (Exception e) {
        }

        str2 = new String(str1);
        flag = encrypt(str2,"126E8F3A5FD52707AFE653E4BFECF723");
        System.out.println(flag);
    }

    public static String encrypt(String arg13, String arg14) {
        int v9;
        int v12 = 256;
        int[] v5 = new int[v12];
        byte[] v3 = new byte[v12];
        int v0;
        for(v0 = 0; v0 < v12; ++v0) {
            v5[v0] = v0;
        }
        v0 = 0;
        while(v0 < v12) {
            v3[v0] = ((byte)arg14.charAt(v0 % arg14.length()));
            v0++;
        }
        int v7 = 0;
        for(v0 = 0; v0 < 255; ++v0) {
            v7 = (v5[v0] + v7 + v3[v0]) % 256;
            v9 = v5[v0];
            v5[v0] = v5[v7];
            v5[v7] = v9;
        }
        v0 = 0;
        v7 = 0;
        char[] v2 = arg13.toCharArray();
        char[] v4 = new char[v2.length];
        int v10 = 0;
        while(v10 < v2.length) {
            v0 = (v0 + 1) % 256;
            v7 = (v5[v0] + v7) % 256;
            v9 = v5[v0];
            v5[v0] = v5[v7];
            v5[v7] = v9;
            v4[v10] = ((char)(v2[v10] ^ (((char)v5[(v5[v0] + v5[v7] % 256) % 256]))));
            v10++;
        }
        return new String(v4);
    }
}