字符加密。将大写字母逐个按其ASCII值转换为

字符加密。将大写字母逐个按其ASCII值转换为7位二进制数，并在最左边补0，使得每个字母转换为8位二进制数，然后将8位二进制数每四位转为十六进制数。如明文是"CIE"，加密后的密文是"434945"。编写的python程序如下，完善划线处的代码。

def xtob(n): #将整数转为二进制数

if n <= 1:

return str(n)

return xtob(n//2) ??①???

mingwen = "CIE"

he = '0123456789ABCDEF'

rst = ''

for c in mingwen:

s = "0" xtob(ord(c)) #将明文转为8位二进制数

i = 0

data = https://tiku.scratchor.com/paper/question_answer/0

while i < 8:

data =https://tiku.scratchor.com/paper/question_answer/data * 2 ??②??

if (i 1) % 4 == 0:

rst = rst he[data]

data = https://tiku.scratchor.com/paper/question_answer/0

????③???

print('密文是:',rst)