Re: [OAUTH-WG] Defining a maximum token length?

Eran Hammer-Lahav <eran@hueniverse.com> Sat, 10 April 2010 05:16 UTC

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From: Eran Hammer-Lahav <eran@hueniverse.com>
To: Allen Tom <atom@yahoo-inc.com>, Luke Shepard <lshepard@facebook.com>, OAuth WG <oauth@ietf.org>
Date: Fri, 09 Apr 2010 22:16:00 -0700
Thread-Topic: [OAUTH-WG] Defining a maximum token length?
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Subject: Re: [OAUTH-WG] Defining a maximum token length?
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I would argue that for the spec to provide a token size limit that is greater than 255 would cause more harm than good. This is not to say I am supporting the 255 limit (I take no position on the matter - yeah, that happens rarely). If the spec provided a 4K limit, client libraries are likely to codify that which will make them extremely wasteful for 99% of the popular cases on the web today. A 4K limit doesn't really improve interop since the limit is so high, no one is likely to issue even bigger tokens with public APIs.

The 255 limit keeps the token size within the most effective database field size limit for this type of identifier. If we cannot reach consensus on this size limit, I don't think the spec should say anything. However, if I wrote a client library, I would make it use a 255 default size limit and require a custom configuration to enable it to use something else.

So my proposal is 255 or no size guidance/restriction.

EHL


On 4/9/10 4:49 PM, "Allen Tom" <atom@yahoo-inc.com> wrote:

I think a good precedent would be to use the HTTP Cookie size limit, which
is 4KB.

An OAuth Access Token is like an HTTP Authorization cookie. They're both
bearer tokens that are used as a credentials for a client to access
protected resources on behalf of the end user.

All Oauth clients have to implement HTTP anyway, so 4KB sounds like a
reasonable limit.

Allen



> On Fri, Apr 9, 2010 at 3:14 AM, Luke Shepard <lshepard@facebook.com> wrote:

>>
>> So, what is a reasonable limit for the token length?  1k? 2k? 4k? 5mb? I
>> suggest some language like this:
>>
>>

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