[Openid-specs-ab] Transient Client Secret Extension for OAuth

John Bradley ve7jtb at ve7jtb.com
Mon Jul 29 07:13:09 UTC 2013

If it is just a hash then it can be precomputed.   Adding a random salt that is hashed with the value sent to the token endpoint prevents pre-computation of the hash.

The issues are the same as with PB-KDF given that we are sending the hash in the clear.  

Yes but if I am a bed person and there is no per password salt I use a precomputed rainbow table and even if I don't cover the entire space eventually I will find a collision if I intercept enough messages.

On 2013-07-29, at 8:29 AM, Nat Sakimura <sakimura at gmail.com> wrote:

> I have thought of that, and I do not think so. 
> Adding salt amounts to expanding the entropy of the input string. 
> So, having enough bit length in the transient secret to start with has the same effect. 
> Since the validity period of the transient secret is rather short, you cannot do the offline attack. 
> The attacker has to have the rainbow table to start with. 
> What we want to make sure is that len(tcs) > max_len(available rainbow table). 
> 2013/7/29 John Bradley <ve7jtb at ve7jtb.com>
> Thinking about it overnight we need to also have a salt sent with the hash, to prevent rainbow tables attacks.
> On 2013-07-28, at 9:39 PM, Nat Sakimura <sakimura at gmail.com> wrote:
>> As some of you knows, passing the code securely to a native app on iOS platform is next to impossible. Malicious application may register the same custom scheme as the victim application and hope to obtain the code, whose success rate is rather high. 
>> We have discussed about it during the OpenID Conenct Meeting at IETF 87 today, and I have captured the discussion in the form of I-D. It is pretty short and hopefully easy to read. 
>> You can find it at: 
>> https://bitbucket.org/Nat/drafts/src/
>> Comments are welcome. 
>> -- 
>> Nat Sakimura (=nat)
>> Chairman, OpenID Foundation
>> http://nat.sakimura.org/
>> @_nat_en
>> _______________________________________________
>> Openid-specs-ab mailing list
>> Openid-specs-ab at lists.openid.net
>> http://lists.openid.net/mailman/listinfo/openid-specs-ab
> -- 
> Nat Sakimura (=nat)
> Chairman, OpenID Foundation
> http://nat.sakimura.org/
> @_nat_en

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