Hi!
I ran in to something curious, but could not find any info on it so I
thought I'll ask.
If there are related posts, please point me to the as my search engine
skills seem to have been insufficient to find them.
Ok lets go.
Problem Setting:
Client C wants to authenticate with Server S using a password to decrypt a
transmitted random, The password is provided by the user, C authenticates
and returns the root object of S.
First C establishes a connection with S using rpyc.ssh_connect(sshctx,
port, service=CustomCallback,config = {"allow_public_attrs" : True,
"allow_all_attrs" : True}
To get the socked used by my rpyc connection I do:
fd = connection.fileno()
sock = socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM)
So then C does:
*snip*
def authenticate_with_blowfish(key, iv, sock):
blowfish = Blowfish.new(key, Blowfish.MODE_CBC, iv)
time.sleep(1)
b64_encrypted_b64 = sock.recv(2048)
encrypted_b64 = base64.b64decode(b64_encrypted_b64)
b64 = blowfish.decrypt(encrypted_b64)
sock.send(b64)
*snip*
On the Server Side there is an authenticator listening which has been
adapted with functools.partial to be accepted by rpyc:
def blowfish_authenticator_partial(key,iv,sock):
blowfish = Blowfish.new(key,Blowfish.MODE_CBC, iv)
random = Random.get_random_bytes(1024)
randomB64 = base64.b64encode(random)
cipher = blowfish.encrypt(randomB64)
cipherB64 = base64.b64encode(cipher)
sock.send(cipherB64)
replyB64 = sock.recv(8188)
decodedReply = base64.b64decode(replyB64)
if decodedReply == random:
return [sock, None]
raise AuthenticationError
Ok. My question is: Why is the time.sleep(1) necessary? I could not get it
working without it but with it this code works like a charm. If I put in
debug statements all statements before the first socket send/recv are
printed.
I run in to a similar problem a second time:
in pseudocode:
authenticate_connection(c)
print c.root
#will fail while
authenticate_connection(c)
time.sleep(1)
print c.root
#will work
My test setting:
2 VM's running Ubuntu 12.04 Server
python 2.7.3
rpyc v3.2.1
Ok. This got rather lengthy but I wanted to give a description which is as
detailed as possible.
This is not intended as bug report, I am just curious as to why this
behavior occurs.
Thanks for taking the time to read through this.
Regards
Eduard
