Ajas,

FWIW, you can either push the info to the remote site to be identified by the ID or have the remote site pull it from you. Your choice, really.

-dhs


Dean H. Saxe, CISSP, CEH
[EMAIL PROTECTED]
"I have always strenuously supported the right of every man to his own opinion, however different that opinion might be to mine. He who denies another this right makes a slave of himself to his present opinion, because he precludes himself the right of changing it."
    -- Thomas Paine, 1783


On Aug 8, 2008, at 12:39 PM, Ajas Mohammed wrote:

Thanks everyone for the replies.

Thanks Dean for giving a detailed insight about encryption and back channel. Thanks Sean for CreateUUID example.

I am glad I am not using encryption now because crazy things were happening, beyond my control.

I am sticking to the idea suggested by pretty much everyone i.e. unique random ID, identifying the transaction which is independent of the user .

Thanks a lot.

Ajas.



On 7/30/08, Dean H. Saxe <[EMAIL PROTECTED]> wrote: BTW, the reason your solution is inappropriate is because you have allowed the user to control the transaction by controlling the data passed between the two systems. By passing the data via a back channel you can remove the user from the authentication mechanism between the two systems and require the user to have previously authenticated via your site before using SSO to the target site. Your solution doesn't require any prior login, since a user could theoretically "guess" a valid login string. (Theoretically being the key term here. Unlikely is another. But it is still not a good idea.)

-dhs


Dean H. Saxe, CISSP, CEH
[EMAIL PROTECTED]
"If liberty means anything at all, it means the right to tell people what they do not want to hear."
   -- George Orwell, 1945



On Jul 30, 2008, at 11:30 AM, Dean H. Saxe wrote:

Ajas,

Your model is broken. Not to say I have never implemented a similar solution, I have. But it is a poor solution which can be significantly improved. (I run into these all the time on penetration tests, so you are not the first or last to try this...)

A valid, strong solution would pass the structure from server to server via a back channel and avoid the user altogether. If done over SSL, there is no need for encryption (beyond the SSL). A unique, time limited, highly random token (not a UUID) would be used to identify the transaction and that is the only information needed by the user, this clearly needs to be provided in the transaction passed via the back channel and should be created from a secure random number generator. The server receiving the SSO request (target server) would need to maintain state of all requests passed by the back channel and remove those requests from its queue when they time out (e.g. <2 minutes after receipt) or when the valid request from the user containing the SSO identifier is received by the target server.

There is little extra work needed for this solution, but the long term time/effort savings are huge by not having to deal with the problems brought up by encryption. Might as well get it right the first time, rather than having to recode a proper solution later after you find out why yours is broken, right?

-dhs

Dean H. Saxe, CISSP, CEH
[EMAIL PROTECTED]
"A true conservationist is a person who knows that the world is not given by his fathers, but borrowed from his children."
-- John James Audubon




On Jul 30, 2008, at 11:10 AM, Ajas Mohammed wrote:

Hi,

Thanks everyone for the suggestions. Those suggestions were really helpful.

Sean, CreateUUID looks like a good idea. I will use it in addition to my logic. Anyone wants to comment anything about that approach.

Dean, The reason I want to encrypt is because I plan to pass a structure as url parameter using wddx and I want to pass it over encrypted, otherwise it looks like simple xml with all values easily seen in url.I have to use wddx because I cant pass structure as url parameter.

Shawn, agreed about management. Honestly, no one asked me todo this. I want to make it as safe as possible using the help from some great minds we have in this group. ;-) .

Ajas.


On 7/29/08, [EMAIL PROTECTED] <[EMAIL PROTECTED] > wrote: Return Receipt

Your Re: [ACFUG Discuss] cflocation with variables encrypted, is
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<Ajas Mohammed />
http://ajashadi.blogspot.com
We cannot become what we need to be, remaining what we are.
No matter what, find a way. Because thats what winners do.
You can't improve what you don't measure.
Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skillful execution; it represents the wise choice of many alternatives.
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