re | [羊城杯 2020]easyre

winx64的pe文件
估计是devc编译的，debugmode

主要逻辑非常简单
base以后两个位变换
直接丢exp了：

from base64 import b64encode, b64decode
aim = "EmBmP5Pmn7QcPU4gLYKv5QcMmB3PWHcP5YkPq3=cT6QckkPckoRG"
p = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234567890+/="

count = len(aim)
print(count)

# 38位
flag = ""

# 从encode3开始爆破
tmp = ‘‘
for i in range(count):
	print(i)
	for j in p:
		if ord(j) <= 0x40 or ord(j) > 0x5a:
			if  ord(j) <= 0x60 or ord(j) > 0x7a:
				if ord(j) <= 0x2f or ord(j) > 0x39:
					t = j
				else:
					t = chr((ord(j)-48+3)%10 + 48)
			else:
				t = chr((ord(j)-97+3)%26 + 97)
		else:
			t = chr((ord(j)-65+3)%26 + 65)
		if t == aim[i]:
			tmp += j
			print(tmp)
			break
print(tmp)
# BjYjM2Mjk4NzMR1dIVHs2NzJjY0MTEzM2VhMn0=zQ3NzhhMzhlOD
# encode2
_tmp = tmp[13:26] + tmp[39:] + tmp[:13] + tmp[26:39]
print(b64decode(_tmp))

overです。