Hi,
What do you think we're trying to do? The official yahoo client uses an MD5 Challenge/Response pair that is near impossible to crack.
I don't know anything about the Yahoo protocol etc. But speaking from a purely cryptographic stand point, this protocol necessarily has to be crackable. In the absence of an external key (i.e. one entered by the user) there is no way to prevent one program from imitating another.
However, it can be immune to a passive attack, i.e. simply listening to communications go back and forth. To break it one would need to reverse-engineer the Yahoo program.
If you can, please help.
If it is legal to do it, I can try to disassemble and reverse-engineer the Yahoo protocol.
Get a packet sniffer (I think you already have one),
tcpdump?
and start working on the authentication part. Look for tcp connects on port 5050 from your machine with the PUSH flag set to 1.
Regards, Vinay vinay@vinaypai.com
Hi,
I just happened to chance upon these postings, and am interested in knowing where I can find info on the Yahoo challange / response protocol.
I need to come up with a similar auth protocol between a client and server that I am writing.
I thought of using a simple maths formula on both sides, generating a random number from one end, passing it through the formula, sending it out, have the client apply the same, return the result and compare it with the first result.
I guess Yahoo does something remotely similar ?? Or am I off track completly ?
Thanks. Shahed.
PS : I know this has nothing to do with Linux. Pls dont flame me as I rarely post and flames just add to the traffic.
On Apr 11, 2002 at 16:17, Shahed Moolji wrote:
and am interested in knowing where I can find info on the Yahoo challange / response protocol.
"challenge".
Yahoo: http://www.venkydude.com/articles/yahoo.htm
MSN: http://www.venkydude.com/articles/msn.htm http://www.atlantageek.com/msn-protocol.html
I configured Mandrake 8.0 to provide internet sharing to my windows clients. The connection on the Mandrake PC is fast enough, but the clients seem to browse very slowly. Any pointers to troubleshoot this?
Thank in advance, Shishir
--- Shishir iamshishir@hotpop.com wrote:
I configured Mandrake 8.0 to provide internet sharing to my windows clients. The connection on the Mandrake PC is fast enough, but the clients seem to
[snip] There can b various reasons shishir.......
--> simply......cause u r on the proxy surfin, the speed is better than the rest as u hav a direct connection and not goin thro the proxy(again this depends on how u hav configured surfin on the mandrake proxy box).
--> The no of clients vs the b/w is another major factor. Our 56K POTS dialup lines r due for a major overhaul if u r talkin terms of delivern last mile hops to ur desktop. shishir....understand..it's like this. No 2 pple can have the same b/w availability due to various reasons linked from bad telephone lines to analog xchanges and el-cheapo win-modems.
--> Hane u enabled cachine on the local mandrake proxy.....this should give pple the impression that the b/w has increased.
Best of luck.
Trevor Warren
browse very slowly. Any pointers to troubleshoot this?
Thank in advance, Shishir
===== ( >- GNU/LINUX, It's all about CHOICE -< ) /~\ __ http://www.qmailtheeasyway.com __ /~\ | ) / mailto: trevorwarren@yahoo.com \ (/ | |_|_ \ Urgent ->9820349221@maxtouch.co.in / _|_| ___________________________________/
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On Thu, 11 Apr 2002, Satya wrote:
and am interested in knowing where I can find info on the Yahoo challange / response protocol.
"challenge".
Sigh. Please read the whole thread before posting these things. This article is about YPSN2. That is what we've been using all this time. That is the one that yahoo no longer supports.
MSN:
We have no problem with MSN.
On Thu, 11 Apr 2002, Shahed Moolji wrote:
I just happened to chance upon these postings, and am interested in knowing where I can find info on the Yahoo challange / response
Well, if we knew where, then this thread wouldn't exist. The purpose of this thread is to generate just such information.
One way of generating a challenge, and I'm guessing is what yahoo does is to use the username, a timestamp and a random number passed through MD5_Update to generate a MD5 hash. This is sent to the client.
The client then has some elaborate algorithm, not too dissimilar from the one use to create MD5 passwords in /etc/shadow. This algorithm hashes the password to generate a new MD5 hash. It probably also hashes the username. Two hashes are sent back which are authenticated by the server.
Dear all
I have installed Redhat 7.2 [kernel 2.4.7-10] on two IBM labtops, the A21 and the T23. I am running a wireless LAN and the IBM wireless cards manufactured by Lucent work fine. I was also able to get the Prism cards working with exactly the same configuration.
However on the IBM T23, only the prism cards work, the IBM cards do not. Does anyone know what the reason could be and how to make it work?
My configuration for the wireless network is
Net device: eth1 kernel module: wavelan I/O number and IRQ have been left blank
Regards
_________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com
On Fri, 12 Apr 2002, Vinay Pai wrote:
What do you think we're trying to do? The official yahoo client uses an MD5 Challenge/Response pair that is near impossible to crack.
I don't know anything about the Yahoo protocol etc. But speaking from a purely cryptographic stand point, this protocol necessarily has to be crackable. In the absence of an external key (i.e. one entered by
The point is we don't know what the key is. If we can figure that out, we'd make some progress. What we do know, is that the yahoo server sends a challenge string - a MD5 hash - that I'm guessing is used somehow to hash the password. Now, this hash that is sent by the server may be generated based on anything, but possibly a timestamp and the userid that is sent through first. We don't really care about that as you said. We care about what the yahoo client does with this hash and the password.
However, it can be immune to a passive attack, i.e. simply listening to communications go back and forth. To break it one would need to reverse-engineer the Yahoo program.
Not necessarily. Just a thought - the libcrypto library being used is free software, so why not just restrict our tracing to what goes into and what comes out of MD5_* functions. That should give us a fair idea of how the hash is being generated. I've done a preliminary analysis, and judging by the number of calls to MD5_Update, I'm guessing that this is almost identical to how pam generates passwords. What's the probability that yahoo would use the same tried and tested algorithm rather than develop their own?
If you can, please help.
If it is legal to do it, I can try to disassemble and reverse-engineer the Yahoo protocol.
The protocol you can reverse-engineer - it is broadcast over a TCP/IP network, which means all packets are available for public inspection. The binary you may not be allowed to, but check the licence agreement anyway.
Get a packet sniffer (I think you already have one),
tcpdump?
ethereal is better for separating out the parts of the packets, and it also understands several protocols.
-
Philip S Tellis -
Satya -
Shahed Moolji -
Shankar Ramchandran -
Shishir -
Trevor Warren -
Vinay Pai