A tricky secure bulk file upload

Last week i came across a situation that, I hav to upload a bulk file of 52 MB through a very unsteady internet connection.This python program is for that,which splits a files into pieces and do an secure copy and reconstruct the file there,at the destination.This script uses the python implementation of expect command in unix,namely pexpect.This is a very useful class,which can be used to execute almost all commands and we can spawn a new process and we can control the session of the process through this class.
here's the script


#!/usr/bin/python
import pexpect
import os
import sys
import getpass

failedlist=[]
def splitter (filename,size,prefix):
os.popen('split -a3 -b %s %s %s'%(size,filename,prefix))
fin,fout=os.popen2('ls %s*'%(prefix))
list=fout.readlines()
return list
def doSsh (user, host, password, command):
"""This runs a command on the remote host. This returns a
pexpect.spawn object. This handles the case when you try
to connect to a new host and ssh asks you if you want to
accept the public key fingerprint and continue connecting.
"""
ssh_newkey = 'Are you sure you want to continue connecting'
child = pexpect.spawn('ssh -l %s %s %s'%(user, host, command))
i = child.expect([pexpect.TIMEOUT, ssh_newkey, 'password: '])
if i == 0: # Timeout
print 'ERROR!'
print 'SSH could not login. Here is what SSH said:'
print child.before, child.after
return None
if i == 1: # SSH does not have the public key. Just accept it.
child.sendline ('yes')
child.expect ('password: ')
i = child.expect([pexpect.TIMEOUT, 'password: '])
if i == 0: # Timeout
print 'ERROR!'
print 'SSH could not login :'
print child.before, child.after
return None
child.sendline(password)
return child
def doScp(filename,user,host,passwd,dest_dir):
ssh_newkey = 'Are you sure you want to continue connecting'
print 'doing scp'
string='scp '+filename+' '+user+'@'+host+':'+dest_dir
print string
child = pexpect.spawn(string)
print 'after spawning'
i = child.expect([pexpect.TIMEOUT, ssh_newkey, 'password: '])
if i == 0: # Timeout
print 'ERROR!'
print 'Copying failed: '
print child.before, child.after
failedlist.append(filename)
return None
if i == 1: # SSH does not have the public key. Just accept it.
child.sendline ('yes')
child.expect ('password: ')
i = child.expect([pexpect.TIMEOUT, 'password: '])
if i == 0: # Timeout
print 'ERROR!'
print 'Copying Failed :'
print child.before, child.after
return None
child.sendline(passwd)
child.expect([pexpect.TIMEOUT, '100%'])
print 'uploading done'
return child


def doUpload(list,user,passwd,host,dest_dir):
for file in list:
doScp(file,user,host,passwd,dest_dir)

list=splitter('install','1m','.splitted.tmp.')
doUpload(list,'root','password','192.168.1.2','/root/')
doSsh('root','192.168.1.2','password','cat .splitted.tmp.* > install')
doSsh('root','192.168.1.2','password','rm -f .splitted.tmp.*')