python脚本 通过rsa private key 生成 publickey

说明：蓝色=命令名称
浅绿=命令参数 浅蓝=选项 紫色=目录
系统环境：CentOS 5.5 x86_64 python版本：Python 2.7.3参考paramiko和pycrypto官方文档写了一个通过rsa private key生成 public key的工具，如下

#!/usr/bin/env python
#-*- coding:utf-8 -*-
#Author:left_left
import struct
import base64
import sys
import os
from optparse import OptionParser
from Crypto.PublicKey import RSA
def get_bin(n):
s = ''
n = long(n)
while (n != 0) and (n != -1):
s = struct.pack('>I', n & 0xffffffffL) + s
n = n >> 32

for i in enumerate(s):
if (n == 0) and (i[1] != '\000'):
break
if (n == -1) and (i[1] != '\xff'):
break

s = s[i[0]:]
if (n == 0) and (ord(s[0]) >= 0x80):
s = '\x00' + s
if (n == -1) and (ord(s[0]) <0x80):
s = '\xff' + s

s = struct.pack(">I", len(s)) + s
return s
def parse():
p = OptionParser()
p.set_usage("command [options] privatekey")
p.add_option('-p', '--publickey', dest = 'publickey', default = './p.pub')
#p.add_option('-v', '--private', dest = 'vf')
p.add_option('-t', '--type', dest = 'type', default = 'ssh-rsa')
return p
def main():
p = parse()
options, args = p.parse_args()

try:
vf = args[0]
except IndexError:
print "Please use '-h/--help' for help!"
sys.exit(1)
try:
f = open(vf)
except IOError, e:
print e
sys.exit(1)

uf = options.publickey
if os.path.exists(uf):
print "%s is exists!" % uf
sys.exit(1)
try:
k = RSA.importKey(f.read())
except ValueError, e:
print e
sys.exit(1)
s = ''
t = options.type
l = len(t)
s = struct.pack('>I%ss' % l, l, t)
e = get_bin(k.e)
n = get_bin(k.n)
b = base64.b64encode(''.join((s, e, n)))

try:
of = open(uf, 'w')
of.write("%s %s\n" % (t, b))
of.close()
except IOError, e:
print e
sys.exit(1)
if __name__ == "__main__":
main()