3字符 → 4字符

83Bite → 46Bite

在 base64 表找对应字符

变表base64

import base64
import string

str1 = "mTyqm7wjODkrNLcWl0eqO8K8gc1BPk1GNLgUpI=="

string1 = "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0987654321/+"
string2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

print (base64.b64decode(str1.translate(str.maketrans(string1,string2))))