[keycloak-dev] PKCE support for Keycloak Adapters (OAuthRequestAuthenticator)

Fri Jun 8 13:35:13 EDT 2018

Hi Marek,

thanks for your helpful feedback!
I extracted the generateRandomData() function from the
generateCodeVerifier() function, which could be
reused for state and UUID generation. I also added a fallback in case
Uint8Array isn't available.

I created a PR with the current implementation for KEYCLOAK-1033 (the issue
subject should be adapted to this)
https://github.com/keycloak/keycloak/pull/5255

What's the best way to implement an automated for this?

Cheers,
Thomas

On Wed, Jun 6, 2018 at 9:12 AM Marek Posolda <mposolda at redhat.com> wrote:

> Hi Thomas,
>
> I think it is great and will be good to support this in our javascript
> adapter OOTB.
>
> Few comments:
> - In keycloak.js, we use "createUUID()" function to generate "nonce" and
> "state" . IMO it will be good if all the things (nonce, state,
> codeVerifier...) are generated through same mechanism. I guess that we
> can use "window.crypto" or "window.msCrypto", but if none of them is
> available, then just fallback to what is currently used in
> "createUUID()" ? Also change the current generating of "nonce" and
> "state" to this as I suppose that "window.crypto" or "window.msCrypto"
> are safer alternatives than our current "createUUID()" ?
>
> - I have same concern as you about localStorage, but don't have any
> better alternative... No idea if sessionStorage is better.
>
> - We should document what browsers supports it. I guess that due to
> fallback for crypto/msCrypto, the "plain" method shouldn't be an issue
> for any browser as codeVerifier will be always generated just fine? But
> I guess that S256, which requires this "Uint8Array" stuff may have
> compatibility issues? Or am I wrong here? The issue is, that people can
> still use very old browsers (For example Windows XP with IE6) and not
> sure how bad it is if those people with old browsers can't authenticate...
>
> Marek
>
>
> On 05/06/18 21:33, Thomas Darimont wrote:
> > Hello,
> >
> > I gave it another spin and tested it with a whole bunch of browsers
> > - Windows (IE11, Edge, Firefox, Chrome)
> > - Linux (Chrome, Firefox)
> >
> > Current changes: (Added IE11 Support)
> >
> https://github.com/keycloak/keycloak/compare/master...thomasdarimont:poc/keycloak-js-pkce-support?expand=0
> >
> > If you want to give it a try, you could use the js-console example from
> >
> >
> https://github.com/keycloak/keycloak/blob/master/examples/js-console/src/main/webapp/index.html
> > and just copy the keycloak.js with the PKCE support into the webapp
> folder
> > an include the script from there.
> >
> > In the initOptions for Keycloak, just add "pkceMethod: 'S256'", e.g.:
> >
> >      var initOptions = {
> >          responseMode: 'fragment',
> >          flow: 'standard',
> >          pkceMethod: 'S256'
> >      };
> >
> > If you look at your browser dev-tools, you should now see, code_challenge
> > and code_challenge_method parameters added to your
> > /auth url. Additionally a code_verifier parameter should be sent with the
> > /token POST request.
> >
> > Some additional remarks:
> >
> > In order to support IE11 I had to use the window.msCrypto APIs and I
> added
> > a fallback if even that is not available.
> > Currently the generated code_verifier is stored in localStorage similar
> to
> > the 'kc-callback-...' values.
> > I think that localStorage is not the best place to store a temporary
> secret
> > ... I'm open to alternatives.
> >
> > The PKCE code_verifier is generated and stored in localStorage when
> > building the auth URL, where either
> > the plain value or an url-safe base64 encoded sha256 has of the
> > code_verifier is used as the code_challenge, depending on the chosen
> method.
> > Instead of localStorage one could probably also just use sessionStorage,
> > which would have the advantage of automatic deletion when the tab /
> browser
> > is closed.
> >
> > The two included libraries could be embedded / scoped into the keycloak
> JS
> > scope to not interfere with other included versions of the libraries.
> >
> > Cheers,
> > Thomas
> >
> > On Thu, May 31, 2018 at 1:09 PM Thomas Darimont <
> > thomas.darimont at googlemail.com> wrote:
> >
> >> Hi folks,
> >>
> >> I've got a working PoC for PKCE support in the Keycloak JS adapter that
> >> supports `plain` and `S256` code_challenge_methods.
> >> Works very well with Keycloak 4.0.0.beta3 and Keycloak 3.4.3.Final.
> >> Perhaps this could serve as a base for a real PR.
> >>
> >> I needed to use two small js libraries to have proper support for sha256
> >> and base64 encoding for Unit8Arrays in order to
> >> produce a codeChallenge in the same way the Keycloak server does it, for
> >> details see commit.
> >>
> >> Branch:
> >>
> https://github.com/thomasdarimont/keycloak/tree/poc/keycloak-js-pkce-support
> >> Commit:
> >>
> https://github.com/thomasdarimont/keycloak/commit/f05066d430f6504246f7e518a124aef2ef5195b8
> >>
> >> Looks like this would solve the issue
> >> https://issues.jboss.org/browse/KEYCLOAK-1033 (which would probably
> need
> >> to be renamed).
> >>
> >> Cheers,
> >> Thomas
> >>
> >> On Wed, May 30, 2018 at 11:57 PM Thomas Darimont <
> >> thomas.darimont at googlemail.com> wrote:
> >>
> >>> Good point. Yes the main use case for PKCE are public clients / native
> >>> apps.
> >>>
> >>> However the recently published OAuth 2.0 Security Best Current Practice
> >>> (Draft 06 2018) [1] states:
> >>> "
> >>> 2.1.  Protecting redirect-based flows
> >>> ...
> >>>   Clients shall use PKCE [RFC7636] in order to (with the help of the
> >>>     authorization server) detect and prevent attempts to inject
> (replay)
> >>>     authorization codes into the authorization response.  The PKCE
> >>>     challenges must be transaction-specific and securely bound to the
> >>>     user agent, in which the transaction was started.  OpenID Connect
> >>>     clients may use the "nonce" parameter of the OpenID Connect
> >>>     authentication request as specified in [OpenID] in conjunction with
> >>>     the corresponding ID Token claim for the same purpose.
> >>>
> >>> Note: although PKCE so far was recommended as mechanism to protect
> >>>     native apps, this advice applies to all kinds of OAuth clients,
> >>>     including web applications.
> >>> "
> >>> The last "Note" section was what inspired me to look into PKCE support
> >>> for server-side adapters as well.
> >>> But I generally agree that this is probably better suited for the JS /
> >>> CLI/ keycloak-installed adapters.
> >>>
> >>> [1] https://tools.ietf.org/html/draft-ietf-oauth-security-topics-06
> >>>
> >>> On Wed, May 30, 2018 at 8:38 AM Stian Thorgersen <sthorger at redhat.com>
> >>> wrote:
> >>>
> >>>> As PKCE is aimed at public clients why is there a need to add support
> >>>> for this to the Java adapters? Makes more sense to add this to the
> >>>> JavaScript adapter and CLI/desktop adapter.
> >>>>
> >>>> On 30 May 2018 at 07:47, 乗松隆志 / NORIMATSU，TAKASHI <
> >>>> takashi.norimatsu.ws at hitachi.com> wrote:
> >>>>
> >>>>> Hello,
> >>>>>
> >>>>> I've encountered the same problem and gave up.
> >>>>>
> >>>>> At that time, the naive idea had hit on me.
> >>>>> * prepare some concurrently accessible singleton (line
> >>>>> KeycloakDeployment) from OAuthRequestAuthenticator
> >>>>> * store generated codeVerifier on it with state parameter value as
> its
> >>>>> key.
> >>>>>
> >>>>> But, considering the nature of codeVerifier, the followings are
> >>>>> required for such the store
> >>>>> * codeVerifier should be treated the same secure levels as client
> >>>>> credentials
> >>>>> * codeVerifier should be short-lived and deleted after its life the
> >>>>> same as Authorization Code
> >>>>>
> >>>>> Therefore, It might be better to create an tentative instance whose
> >>>>> lifetime is between issuing Authorization Code Request and issuing
> Token
> >>>>> Request. And, it should be identified and only accessible from the
> session
> >>>>> instance who issued Authorization Code Request.
> >>>>>
> >>>>> However, I'm afraid it might be difficult to accomplish it in generic
> >>>>> fashion. We need to implement the above each type of client adapter.
> >>>>>
> >>>>> Best regards,
> >>>>> Takashi Norimatsu
> >>>>> Hitachi Ltd.,
> >>>>>
> >>>>> -----Original Message-----
> >>>>> From: keycloak-dev-bounces at lists.jboss.org <
> >>>>> keycloak-dev-bounces at lists.jboss.org> On Behalf Of Thomas Darimont
> >>>>> Sent: Wednesday, May 30, 2018 9:02 AM
> >>>>> To: keycloak-dev <keycloak-dev at lists.jboss.org>
> >>>>> Subject: [!][keycloak-dev] PKCE support for Keycloak Adapters
> >>>>> (OAuthRequestAuthenticator)
> >>>>>
> >>>>> Hi there,
> >>>>>
> >>>>> I was recently playing with the PKCE support in Keycloak (server)
> which
> >>>>> worked quite well.
> >>>>> However the support for client / adapters seems to be quite limited
> at
> >>>>> the moment...
> >>>>>
> >>>>> I think support for PKCE to all? java adapters could be added quite
> >>>>> easily
> >>>>> - I could provide a
> >>>>> PR but I'm currently stuck with finding a generic way to store the
> >>>>> codeVerifier generated for the login redirect for later retrival for
> the
> >>>>> code2token exchange.
> >>>>>
> >>>>> Do you have any recommendations for this?
> >>>>>
> >>>>> I created the following JIRA issue (with some comments) to track
> this:
> >>>>>
> >>>>>
> https://clicktime.symantec.com/a/1/bkUjActRvyW1Ds3zoQSu7mjr4Nabixm_1YJAW4-UxEM=?d=d5OUWVTwLT2kMkuISm5qn8WHJTBcSVkENKzaB0Z2mA-PX8kp40LeKyOrcMpyKd841kYgP2EXaDDWYa0qu-AFLCtVLO4LvMfUJgUhu3xFwONMPy78dypmmmeEalkcYLU4XY3LcstbfVAoE0jRdEXXMyYStWwO95V_98pfhIYFlYFIHgapXJsFfGrldL8-siYGhinjnCn_AWyuyqrwhvBY582Dr3Pn9k4YZfsudBwcSJkErQKzyYEKfMhwz4ix7EAa-hvQ6rGHFdSza3jf1cMjsR4Xio667eNtirL9ruV4Z-FFQhamJMSJGb2o8rR52iEuGTp_28Vivk5HiwYx5XhZ4Bm9_dhN2eNeWT396bZQJwC7tDetr6UPVrPiMn6aTLdGMu6Wr-byBNvnEFmqxCB0Cx1tPxQkO4DVWKF4_iWgxZ6sW49k87BqaRTp3ktECRXNJ-CA04UZQbL7w-uPYlxvyvNNl408bCn5LpYf8w%3D%3D&u=https%3A%2F%2Fissues.jboss.org%2Fbrowse%2FKEYCLOAK-7467
> >>>>>
> >>>>> Cheers,
> >>>>> Thomas
> >>>>> _______________________________________________
> >>>>> keycloak-dev mailing list
> >>>>> keycloak-dev at lists.jboss.org
> >>>>>
> >>>>>
> https://clicktime.symantec.com/a/1/Xn2ffdZIVPL_UA8_cnNApcirkcZZdsnyb6SpUdKiO-s=?d=d5OUWVTwLT2kMkuISm5qn8WHJTBcSVkENKzaB0Z2mA-PX8kp40LeKyOrcMpyKd841kYgP2EXaDDWYa0qu-AFLCtVLO4LvMfUJgUhu3xFwONMPy78dypmmmeEalkcYLU4XY3LcstbfVAoE0jRdEXXMyYStWwO95V_98pfhIYFlYFIHgapXJsFfGrldL8-siYGhinjnCn_AWyuyqrwhvBY582Dr3Pn9k4YZfsudBwcSJkErQKzyYEKfMhwz4ix7EAa-hvQ6rGHFdSza3jf1cMjsR4Xio667eNtirL9ruV4Z-FFQhamJMSJGb2o8rR52iEuGTp_28Vivk5HiwYx5XhZ4Bm9_dhN2eNeWT396bZQJwC7tDetr6UPVrPiMn6aTLdGMu6Wr-byBNvnEFmqxCB0Cx1tPxQkO4DVWKF4_iWgxZ6sW49k87BqaRTp3ktECRXNJ-CA04UZQbL7w-uPYlxvyvNNl408bCn5LpYf8w%3D%3D&u=https%3A%2F%2Flists.jboss.org%2Fmailman%2Flistinfo%2Fkeycloak-dev
> >>>>>
> >>>>> _______________________________________________
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> >>>>> keycloak-dev at lists.jboss.org
> >>>>> https://lists.jboss.org/mailman/listinfo/keycloak-dev
> >>>>>
> >>>>
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