题目：编码+异或
R0I0RElPSk1HQjRESU1aTUdCNERJWkpNR0I0RElPQk1HQjRES05CTUdCNERPT0JNR0I0RElZSk1HQjRESU1aTUdCNERJWVpNR0I0RElNQk1HQjRESU1STUdCNERJWUpNR0I0RE9NQk1HQjRET1lSTUdCNERJTUJNR0I0RE9NQk1HQjRET05KTUdCNERPTkpNR0I0RE9ZSk1HQjRHS0xCUVBBMlRFQ1E9

ctf在线解码： http://ctf.ssleye.com/
由编码尝试b64
得到 
GB4DIOJMGB4DIMZMGB4DIZJMGB4DIOBMGB4DKNBMGB4DOOBMGB4DIYJMGB4DIMZMGB4DIYZMGB4DIMBMGB4DIMRMGB4DIYJMGB4DOMBMGB4DOYRMGB4DIMBMGB4DOMBMGB4DONJMGB4DONJMGB4DOYJMGB4GKLBQPA2TECQ=
全部大写并且尾部带有等号
再次b32解码得到： 
0x49,0x43,0x4e,0x48,0x54,0x78,0x4a,0x43,0x4c,0x40,0x42,0x4a,0x70,0x7b,0x40,0x70,0x75,0x75,0x7a,0xe,0x52
即：
73 67 78 72 84 120 74 67 76 64 66 74 112 123 64 112 117 117 122 14 82
题目给有异或提示，尝试多种方法后，发现是将每一位都与一个相同的数异或
73(" I ")：1001001
res:          1100110   ---- 47
102(" f "): 1100110
逐位异或后得到flag{Welcome_To_ZZU!}