urlsafe_b64encode总是以'='结尾？:

Question

我认为这一定是一个愚蠢的问题,但为什么urlsafe_b64encode()的结果总是以'='结尾？'='不是网址安全吗？

from random import getrandbits
from base64 import urlsafe_b64encode
from hashlib import sha256
from time import sleep

def genKey():
   keyLenBits = 64
   a = str(getrandbits(keyLenBits))
   b = urlsafe_b64encode(sha256(a).digest())
   print b

while 1:
   genKey()
   sleep(1)

输出:

DxFOVxWvvzGdOSh2ARkK-2XPXNavnpiCkD6RuKLffvA=
xvA99ZLBrLvtf9-k0-YUFcLsiKl8Q8KmkD7ahIqPZ5Y=
jYbNK7j62KCBA5gnoiSpM2AGOPxmyQTIJIl_wWdOwoY=
CPIKkXPfIX4bd8lQtUj1dYG3ZOBxmZTMkVpmR7Uvu4s=
HlTs0tBW805gaxfMrq3OPOa6Crg7MsLSLnqe-eX0JEA=
FKRu0ePZEppHsvACWYssL1b2uZhjy9UU5LI8sWIqHe8=
aY_kVaT8kjB4RRfp3S6xG2vJaL0vAwQPifsBcN1LYvo=
6Us3XsewqnEcovMb5EEPtf4Fp4ucWfjPVso-UkRuaRc=
_vAI943yOWs3t2F6suUGy47LJjQsgi_XLiMKhYZnm9M=
CcUSXVqPNT_eb8VXasFXhvNosPOWQQWjGlipQp_68aY=

Answer 1

Base64使用'='进行填充.你的字符串位长度不能被24整除,所以它用'='填充.顺便说一下,'='应该是URL安全的,因为它经常用于URL中的参数.

也请参阅此讨论.