import re  
def is_allowed_specific_char(string):  
    charRe = re.compile(r'[^a-zA-Z0-9.]')  
    string = charRe.search(string)  
    return not bool(string)  
  
print(is_allowed_specific_char("ABCDEFabcdef123450"))   
print(is_allowed_specific_char("*&%@#!}{"))