diff --git a/.github/ISSUE_TEMPLATE/bug_report.md b/.github/ISSUE_TEMPLATE/bug_report.md
new file mode 100644
index 0000000..49ccc49
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/bug_report.md
@@ -0,0 +1,38 @@
+---
+name: 🐛 Bug report
+about: Create a report to help us improve
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Desktop (please complete the following information):**
+- OS: [e.g. iOS]
+- Browser [e.g. chrome, safari]
+- Version [e.g. 22]
+
+**Smartphone (please complete the following information):**
+- Device: [e.g. iPhone6]
+- OS: [e.g. iOS8.1]
+- Browser [e.g. stock browser, safari]
+- Version [e.g. 22]
+
+**Additional context**
+Add any other context about the problem here.
\ No newline at end of file
diff --git a/.github/ISSUE_TEMPLATE/config.yml b/.github/ISSUE_TEMPLATE/config.yml
new file mode 100644
index 0000000..a49eab2
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/config.yml
@@ -0,0 +1 @@
+blank_issues_enabled: true
\ No newline at end of file
diff --git a/.github/ISSUE_TEMPLATE/feature_request.md b/.github/ISSUE_TEMPLATE/feature_request.md
new file mode 100644
index 0000000..118d30e
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/feature_request.md
@@ -0,0 +1,20 @@
+---
+name: 🚀 Feature request
+about: Suggest an idea for this project
+title: ''
+labels: enhancement
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index e5ca513..6e4ab89 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -1,11 +1,18 @@
 name: Release
-on: push
+on:
+  push:
+    branches:
+      - '**'
+    tags-ignore:
+      - '**'
+  workflow_dispatch:
+
 jobs:
   test:
     runs-on: ubuntu-18.04
     strategy:
       matrix:
-        go: ['1.14', '1.15', '1.16']
+        go: ['1.14', '1.15', '1.16', '1.17']
     name: Go ${{ matrix.go }} test
     steps:
       - uses: actions/checkout@v2
@@ -14,13 +21,14 @@ jobs:
         with:
           go-version: ${{ matrix.go }}
       - run: go test -race -v -coverprofile=profile.cov ./pkg/...
-      - uses: codecov/codecov-action@v1
+      - uses: codecov/codecov-action@v2.1.0
         with:
           file: ./profile.cov
           name: codecov-go
   release:
     runs-on: ubuntu-18.04
     needs: [test]
+    if: ${{ github.event_name == 'workflow_dispatch' || github.ref == 'refs/heads/main' }}
     env:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
diff --git a/.releaserc.js b/.releaserc.js
index d9c7f99..6500ace 100644
--- a/.releaserc.js
+++ b/.releaserc.js
@@ -1,8 +1,8 @@
 module.exports = {
-    branch: 'master',
+    branches: ["main"],
     plugins: [
         "@semantic-release/commit-analyzer",
         "@semantic-release/release-notes-generator",
         "@semantic-release/github"
     ]
-  };
\ No newline at end of file
+};
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..b107ae4
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,128 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, religion, or sexual identity
+and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, viewpoints, and experiences
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the
+  overall community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or
+  advances of any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email
+  address, without their explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official e-mail address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the community leaders responsible for enforcement at
+abuse@zitadel.ch.
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series
+of actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or
+permanent ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior,  harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within
+the community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.0, available at
+https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.
+
+Community Impact Guidelines were inspired by [Mozilla's code of conduct
+enforcement ladder](https://github.com/mozilla/diversity).
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see the FAQ at
+https://www.contributor-covenant.org/faq. Translations are available at
+https://www.contributor-covenant.org/translations.
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..f0c8ac7
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,40 @@
+# How to contribute to the OIDC SDK for Go
+
+## Did you find a bug?
+
+Please file an issue [here](https://github.com/caos/oidc/issues/new?assignees=&labels=bug&template=bug_report.md&title=).
+
+Bugs are evaluated every day as soon as possible.
+
+## Enhancement
+
+Do you miss a feature? Please file an issue [here](https://github.com/caos/oidc/issues/new?assignees=&labels=enhancement&template=feature_request.md&title=)
+
+Enhancements are discussed and evaluated every Wednesday by the ZITADEL core team.
+
+## Grab an Issues
+
+We add the label "good first issue" for problems we think are a good starting point to contribute to the OIDC SDK.
+
+* [Issues for first time contributors](https://github.com/caos/oidc/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
+* [All issues](https://github.com/caos/oidc/issues)
+
+### Make a PR
+
+If you like to contribute fork the OIDC repository. After you implemented the new feature create a PullRequest in the OIDC reposiotry.
+
+Make sure you use semantic release:
+
+* feat: New Feature
+* fix: Bug Fix
+* docs: Documentation
+
+## Want to use the library?
+
+Checkout the [examples folder](example) for different client and server implementations.
+
+Or checkout how we use it ourselves in our OpenSource Identity and Access Management [ZITADEL](https://github.com/caos/zitadel).
+
+## **Did you find a security flaw?**
+
+* Please read [Security Policy](SECURITY.md).
\ No newline at end of file
diff --git a/README.md b/README.md
index f7b4365..ef428ed 100644
--- a/README.md
+++ b/README.md
@@ -7,11 +7,13 @@
 [![Go Report Card](https://goreportcard.com/badge/github.com/caos/oidc)](https://goreportcard.com/report/github.com/caos/oidc)
 [![codecov](https://codecov.io/gh/caos/oidc/branch/master/graph/badge.svg)](https://codecov.io/gh/caos/oidc)
 
-> This project is in beta state. It can AND will continue breaking until version 1.0.0 is released
+![openid_certified](https://cloud.githubusercontent.com/assets/1454075/7611268/4d19de32-f97b-11e4-895b-31b2455a7ca6.png)
 
 ## What Is It
 
-This project is a easy to use client and server implementation for the `OIDC` (Open ID Connect) standard written for `Go`.
+This project is a easy to use client (RP) and server (OP) implementation for the `OIDC` (Open ID Connect) standard written for `Go`.
+
+The RP is certified for the [basic](https://www.certification.openid.net/plan-detail.html?public=true&plan=uoprP0OO8Z4Qo) and [config](https://www.certification.openid.net/plan-detail.html?public=true&plan=AYSdLbzmWbu9X) profile.
 
 Whenever possible we tried to reuse / extend existing packages like `OAuth2 for Go`.
 
@@ -44,6 +46,7 @@ For your convenience you can find the relevant standards linked below.
 | 1.14    | :white_check_mark: |
 | 1.15    | :white_check_mark: |
 | 1.16    | :white_check_mark: |
+| 1.17    | :white_check_mark: |
 
 ## Why another library
 
@@ -51,7 +54,6 @@ As of 2020 there are not a lot of `OIDC` library's in `Go` which can handle serv
 
 ### Goals
 
-- [Certify this library as RP](https://openid.net/certification/#RPs)
 - [Certify this library as OP](https://openid.net/certification/#OPs)
 
 ### Other Go OpenID Connect library's
diff --git a/go.mod b/go.mod
index e582c70..a340df8 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,7 @@ require (
 	github.com/golang/mock v1.6.0
 	github.com/google/go-cmp v0.5.2 // indirect
 	github.com/google/go-github/v31 v31.0.0
-	github.com/google/uuid v1.2.0
+	github.com/google/uuid v1.3.0
 	github.com/gorilla/handlers v1.5.1
 	github.com/gorilla/mux v1.8.0
 	github.com/gorilla/schema v1.2.0
@@ -16,7 +16,7 @@ require (
 	github.com/sirupsen/logrus v1.8.1
 	github.com/stretchr/testify v1.7.0
 	golang.org/x/oauth2 v0.0.0-20200902213428-5d25da1a8d43
-	golang.org/x/text v0.3.6
+	golang.org/x/text v0.3.7
 	gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b // indirect
 	gopkg.in/square/go-jose.v2 v2.6.0
 )
diff --git a/go.sum b/go.sum
index d08c4eb..4ff0c39 100644
--- a/go.sum
+++ b/go.sum
@@ -50,9 +50,13 @@ github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1m
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/felixge/httpsnoop v1.0.1 h1:lvB5Jl89CsZtGIWuTcDM1E/vkVs49/Ml7JJe07l8SPQ=
 github.com/felixge/httpsnoop v1.0.1/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
+github.com/gin-contrib/sse v0.1.0/go.mod h1:RHrZQHXnP2xjPF+u1gW/2HnVO7nvIa9PG3Gm+fLHvGI=
+github.com/gin-gonic/gin v1.5.0/go.mod h1:Nd6IXA8m5kNZdNEHMBd93KT+mdY3+bewLgRvmCsR2Do=
 github.com/go-gl/glfw v0.0.0-20190409004039-e6da0acd62b1/go.mod h1:vR7hzQXu2zJy9AVAgeJqvqgH9Q5CA+iKCZ2gyEVpxRU=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20191125211704-12ad95a8df72/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
+github.com/go-playground/locales v0.12.1/go.mod h1:IUMDtCfWo/w/mtMfIE/IG2K+Ey3ygWanZIBtBW0W2TM=
+github.com/go-playground/universal-translator v0.16.0/go.mod h1:1AnU7NaIRDWWzGEKwgtJRd2xk99HeFyHw3yid4rvQIY=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20191227052852-215e87163ea7/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
@@ -95,6 +99,7 @@ github.com/google/go-github/v31 v31.0.0 h1:JJUxlP9lFK+ziXKimTCprajMApV1ecWD4NB6C
 github.com/google/go-github/v31 v31.0.0/go.mod h1:NQPZol8/1sMoWYGN2yaALIBytu17gAWfhbweiEed3pM=
 github.com/google/go-querystring v1.0.0 h1:Xkwi/a1rcvNg1PPYe5vI8GbeBY/jrVuDX5ASuANWTrk=
 github.com/google/go-querystring v1.0.0/go.mod h1:odCYkC5MyYFN7vkCjXpyrEuKhc/BUO6wN/zVPAxq5ck=
+github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
 github.com/google/martian/v3 v3.0.0/go.mod h1:y5Zk1BBys9G+gd6Jrk0W3cC1+ELVxBWuIGO+w/tUAp0=
 github.com/google/pprof v0.0.0-20181206194817-3ea8567a2e57/go.mod h1:zfwlbNMJ+OItoe0UupaVj+oy1omPYYDuagoSzA8v9mc=
@@ -105,8 +110,8 @@ github.com/google/pprof v0.0.0-20200229191704-1ebb73c60ed3/go.mod h1:ZgVRPoUq/hf
 github.com/google/pprof v0.0.0-20200430221834-fc25d7d30c6d/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM=
 github.com/google/pprof v0.0.0-20200708004538-1a94d8640e99/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
-github.com/google/uuid v1.2.0 h1:qJYtXnJRWmpe7m/3XlyhrsLrEURqHRM2kxzoxXqyUDs=
-github.com/google/uuid v1.2.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
+github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
 github.com/gorilla/handlers v1.5.1 h1:9lRY6j8DEeeBT10CvO9hGW0gmky0BprnvDI5vfhUHH4=
@@ -120,6 +125,7 @@ github.com/gorilla/securecookie v1.1.1/go.mod h1:ra0sb63/xPlUeL+yeDciTfxMRAA+MP+
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
+github.com/json-iterator/go v1.1.7/go.mod h1:KdQUCv79m/52Kvf8AW2vK1V8akMuk1QjK/uOdHXbAo4=
 github.com/jstemmer/go-junit-report v0.0.0-20190106144839-af01ea7f8024/go.mod h1:6v2b51hI/fHJwM22ozAgKL4VKDeJcHhJFhtBdhmNjmU=
 github.com/jstemmer/go-junit-report v0.9.1/go.mod h1:Brl9GWCQeLvo8nXZwPNNblvFj/XSXhF0NWZEnDohbsk=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
@@ -129,21 +135,30 @@ github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORN
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/leodido/go-urn v1.1.0/go.mod h1:+cyI34gQWZcE1eQU7NVgKkkzdXDQHr1dBMtdAPozLkw=
+github.com/mattn/go-isatty v0.0.9/go.mod h1:YNRxwqDuOph6SZLI9vUUz6OYw3QyUt7WiY2yME+cCiQ=
+github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
+github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
+github.com/rs/cors v1.8.0 h1:P2KMzcFwrPoSjkF1WLRPsp3UMLyql8L4v9hQpVeK5so=
+github.com/rs/cors v1.8.0/go.mod h1:EBwu+T5AvHOcXwvZIkQFjUN6s8Czyqw12GL/Y0tUyRM=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
 github.com/sirupsen/logrus v1.8.1 h1:dJKuHgqk1NNQlqoA6BTlM1Wf9DOH3NBjQyu0h9+AZZE=
 github.com/sirupsen/logrus v1.8.1/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=
+github.com/ugorji/go/codec v1.1.7/go.mod h1:Ax+UKWsSmolVDwsd+7N3ZtXu+yMGCf907BLYF3GoBXY=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
@@ -244,6 +259,7 @@ golang.org/x/sys v0.0.0-20190507160741-ecd444e8653b/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190606165138-5da285871e9c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190624142023-c5567b49c5d0/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191001151750-bb3f8db39f24/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -272,8 +288,8 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
-golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -403,6 +419,8 @@ gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b h1:QRR6H1YWRnHb4Y/HeNFCTJLFVxaq6wH4YuVdsUOr75U=
 gopkg.in/check.v1 v1.0.0-20200902074654-038fdea0a05b/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
+gopkg.in/go-playground/assert.v1 v1.2.1/go.mod h1:9RXL0bg/zibRAgZUYszZSwO/z8Y/a8bDuhia5mkpMnE=
+gopkg.in/go-playground/validator.v9 v9.29.1/go.mod h1:+c9/zcJMFNgbLvly1L1V+PpxWdVbfP1avr/N00E2vyQ=
 gopkg.in/square/go-jose.v2 v2.6.0 h1:NGk74WTnPKBNUhNzQX7PYcTLUjoq7mzKk2OKbvwk2iI=
 gopkg.in/square/go-jose.v2 v2.6.0/go.mod h1:M9dMgbHiYLoDGQrXy7OpJDJWiKiU//h+vD76mk0e1AI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/pkg/client/rp/jwks.go b/pkg/client/rp/jwks.go
index 98ed501..4062ab4 100644
--- a/pkg/client/rp/jwks.go
+++ b/pkg/client/rp/jwks.go
@@ -3,26 +3,41 @@ package rp
 import (
 	"context"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"net/http"
 	"sync"
 
 	"github.com/caos/oidc/pkg/utils"
-
 	"gopkg.in/square/go-jose.v2"
 
 	"github.com/caos/oidc/pkg/oidc"
 )
 
-func NewRemoteKeySet(client *http.Client, jwksURL string) oidc.KeySet {
-	return &remoteKeySet{httpClient: client, jwksURL: jwksURL}
+func NewRemoteKeySet(client *http.Client, jwksURL string, opts ...func(*remoteKeySet)) oidc.KeySet {
+	keyset := &remoteKeySet{httpClient: client, jwksURL: jwksURL}
+	for _, opt := range opts {
+		opt(keyset)
+	}
+	return keyset
+}
+
+//SkipRemoteCheck will suppress checking for new remote keys if signature validation fails with cached keys
+//and no kid header is set in the JWT
+//
+//this might be handy to save some unnecessary round trips in cases where the JWT does not contain a kid header and
+//there is only a single remote key
+//please notice that remote keys will then only be fetched if cached keys are empty
+func SkipRemoteCheck() func(set *remoteKeySet) {
+	return func(set *remoteKeySet) {
+		set.skipRemoteCheck = true
+	}
 }
 
 type remoteKeySet struct {
-	jwksURL    string
-	httpClient *http.Client
-	defaultAlg string
+	jwksURL         string
+	httpClient      *http.Client
+	defaultAlg      string
+	skipRemoteCheck bool
 
 	// guard all other fields
 	mu sync.Mutex
@@ -72,23 +87,67 @@ func (r *remoteKeySet) VerifySignature(ctx context.Context, jws *jose.JSONWebSig
 	if alg == "" {
 		alg = r.defaultAlg
 	}
-	keys := r.keysFromCache()
-	key, ok := oidc.FindKey(keyID, oidc.KeyUseSignature, alg, keys...)
-	if ok && keyID != "" {
-		payload, err := jws.Verify(&key)
-		return payload, err
+	payload, err := r.verifySignatureCached(jws, keyID, alg)
+	if payload != nil {
+		return payload, nil
 	}
+	if err != nil {
+		return nil, err
+	}
+	return r.verifySignatureRemote(ctx, jws, keyID, alg)
+}
 
+//verifySignatureCached checks for a matching key in the cached key list
+//
+//if there is only one possible, it tries to verify the signature and will return the payload if successful
+//
+//it only returns an error if signature validation fails and keys exactMatch which is if either:
+// - both kid are empty and skipRemoteCheck is set to true
+// - or both (JWT and JWK) kid are equal
+//
+//otherwise it will return no error (so remote keys will be loaded)
+func (r *remoteKeySet) verifySignatureCached(jws *jose.JSONWebSignature, keyID, alg string) ([]byte, error) {
+	keys := r.keysFromCache()
+	if len(keys) == 0 {
+		return nil, nil
+	}
+	key, err := oidc.FindMatchingKey(keyID, oidc.KeyUseSignature, alg, keys...)
+	if err != nil {
+		//no key / multiple found, try with remote keys
+		return nil, nil //nolint:nilerr
+	}
+	payload, err := jws.Verify(&key)
+	if payload != nil {
+		return payload, nil
+	}
+	if !r.exactMatch(key.KeyID, keyID) {
+		//no exact key match, try getting better match with remote keys
+		return nil, nil
+	}
+	return nil, fmt.Errorf("signature verification failed: %w", err)
+}
+
+func (r *remoteKeySet) exactMatch(jwkID, jwsID string) bool {
+	if jwkID == "" && jwsID == "" {
+		return r.skipRemoteCheck
+	}
+	return jwkID == jwsID
+}
+
+func (r *remoteKeySet) verifySignatureRemote(ctx context.Context, jws *jose.JSONWebSignature, keyID, alg string) ([]byte, error) {
 	keys, err := r.keysFromRemote(ctx)
 	if err != nil {
-		return nil, fmt.Errorf("fetching keys %v", err)
+		return nil, fmt.Errorf("unable to fetch key for signature validation: %w", err)
 	}
-	key, ok = oidc.FindKey(keyID, oidc.KeyUseSignature, alg, keys...)
-	if ok {
-		payload, err := jws.Verify(&key)
-		return payload, err
+	key, err := oidc.FindMatchingKey(keyID, oidc.KeyUseSignature, alg, keys...)
+	if err != nil {
+		return nil, fmt.Errorf("unable to validate signature: %w", err)
 	}
-	return nil, errors.New("invalid key")
+	payload, err := jws.Verify(&key)
+	if err != nil {
+		return nil, fmt.Errorf("signature verification failed: %w", err)
+	}
+	return payload, nil
 }
 
 func (r *remoteKeySet) keysFromCache() (keys []jose.JSONWebKey) {
diff --git a/pkg/client/rp/relaying_party.go b/pkg/client/rp/relaying_party.go
index c9c7a8c..669a910 100644
--- a/pkg/client/rp/relaying_party.go
+++ b/pkg/client/rp/relaying_party.go
@@ -2,6 +2,7 @@ package rp
 
 import (
 	"context"
+	"encoding/base64"
 	"errors"
 	"net/http"
 	"strings"
@@ -288,7 +289,7 @@ func AuthURLHandler(stateFn func() string, rp RelyingParty) http.HandlerFunc {
 
 //GenerateAndStoreCodeChallenge generates a PKCE code challenge and stores its verifier into a secure cookie
 func GenerateAndStoreCodeChallenge(w http.ResponseWriter, rp RelyingParty) (string, error) {
-	codeVerifier := uuid.New().String()
+	codeVerifier := base64.RawURLEncoding.EncodeToString([]byte(uuid.New().String()))
 	if err := rp.CookieHandler().SetCookie(w, pkceCode, codeVerifier); err != nil {
 		return "", err
 	}
diff --git a/pkg/oidc/keyset.go b/pkg/oidc/keyset.go
index adfffcf..3eca654 100644
--- a/pkg/oidc/keyset.go
+++ b/pkg/oidc/keyset.go
@@ -5,6 +5,7 @@ import (
 	"crypto/ecdsa"
 	"crypto/ed25519"
 	"crypto/rsa"
+	"errors"
 
 	"gopkg.in/square/go-jose.v2"
 )
@@ -13,6 +14,11 @@ const (
 	KeyUseSignature = "sig"
 )
 
+var (
+	ErrKeyMultiple = errors.New("multiple possible keys match")
+	ErrKeyNone     = errors.New("no possible keys matches")
+)
+
 //KeySet represents a set of JSON Web Keys
 // - remotely fetch via discovery and jwks_uri -> `remoteKeySet`
 // - held by the OP itself in storage -> `openIDKeySet`
@@ -39,20 +45,38 @@ func GetKeyIDAndAlg(jws *jose.JSONWebSignature) (string, string) {
 //will return the key immediately if matches exact (id, usage, type)
 //
 //will return false none or multiple match
+//
+//deprecated: use FindMatchingKey which will return an error (more specific) instead of just a bool
+//moved implementation already to FindMatchingKey
 func FindKey(keyID, use, expectedAlg string, keys ...jose.JSONWebKey) (jose.JSONWebKey, bool) {
+	key, err := FindMatchingKey(keyID, use, expectedAlg, keys...)
+	return key, err == nil
+}
+
+//FindMatchingKey searches the given JSON Web Keys for the requested key ID, usage and key type
+//
+//will return the key immediately if matches exact (id, usage, type)
+//
+//will return a specific error if none (ErrKeyNone) or multiple (ErrKeyMultiple) match
+func FindMatchingKey(keyID, use, expectedAlg string, keys ...jose.JSONWebKey) (key jose.JSONWebKey, err error) {
 	var validKeys []jose.JSONWebKey
-	for _, key := range keys {
-		if key.KeyID == keyID && key.Use == use && algToKeyType(key.Key, expectedAlg) {
-			if keyID != "" {
-				return key, true
+	for _, k := range keys {
+		if k.Use == use && algToKeyType(k.Key, expectedAlg) {
+			if k.KeyID == keyID && keyID != "" {
+				return k, nil
+			}
+			if k.KeyID == "" || keyID == "" {
+				validKeys = append(validKeys, k)
 			}
-			validKeys = append(validKeys, key)
 		}
 	}
 	if len(validKeys) == 1 {
-		return validKeys[0], true
+		return validKeys[0], nil
 	}
-	return jose.JSONWebKey{}, false
+	if len(validKeys) > 1 {
+		return key, ErrKeyMultiple
+	}
+	return key, ErrKeyNone
 }
 
 func algToKeyType(key interface{}, alg string) bool {
diff --git a/pkg/oidc/keyset_test.go b/pkg/oidc/keyset_test.go
new file mode 100644
index 0000000..802edec
--- /dev/null
+++ b/pkg/oidc/keyset_test.go
@@ -0,0 +1,319 @@
+package oidc
+
+import (
+	"crypto/rsa"
+	"errors"
+	"reflect"
+	"testing"
+
+	"gopkg.in/square/go-jose.v2"
+)
+
+func TestFindKey(t *testing.T) {
+	type args struct {
+		keyID       string
+		use         string
+		expectedAlg string
+		keys        []jose.JSONWebKey
+	}
+	type res struct {
+		key jose.JSONWebKey
+		err error
+	}
+	tests := []struct {
+		name string
+		args args
+		res  res
+	}{
+		{
+			"no keys, ErrKeyNone",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys:        nil,
+			},
+			res{
+				key: jose.JSONWebKey{},
+				err: ErrKeyNone,
+			},
+		},
+		{
+			"single key enc, ErrKeyNone",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "enc",
+						Key: &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{},
+				err: ErrKeyNone,
+			},
+		},
+		{
+			"single key wrong algorithm, ErrKeyNone",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "sig",
+						Key: &rsa.PrivateKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{},
+				err: ErrKeyNone,
+			},
+		},
+		{
+			"single key no kid, no jwt kid, match",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{
+					Use: "sig",
+					Key: &rsa.PublicKey{},
+				},
+				err: nil,
+			},
+		},
+		{
+			"single key kid, jwt no kid, match",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use:   "sig",
+						KeyID: "id",
+						Key:   &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{
+					Use:   "sig",
+					KeyID: "id",
+					Key:   &rsa.PublicKey{},
+				},
+				err: nil,
+			},
+		},
+		{
+			"single key no kid, jwt with kid, match",
+			args{
+				keyID:       "id",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{
+					Use: "sig",
+					Key: &rsa.PublicKey{},
+				},
+				err: nil,
+			},
+		},
+		{
+			"single key wrong kid, ErrKeyNone",
+			args{
+				keyID:       "id",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use:   "sig",
+						KeyID: "id2",
+						Key:   &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{},
+				err: ErrKeyNone,
+			},
+		},
+		{
+			"multiple keys no kid, jwt no kid, ErrKeyMultiple",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{},
+				err: ErrKeyMultiple,
+			},
+		},
+		{
+			"multiple keys with kid, jwt no kid, ErrKeyMultiple",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use:   "sig",
+						KeyID: "id1",
+						Key:   &rsa.PublicKey{},
+					},
+					{
+						Use:   "sig",
+						KeyID: "id2",
+						Key:   &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{},
+				err: ErrKeyMultiple,
+			},
+		},
+		{
+			"multiple keys, single sig key, jwt no kid, match",
+			args{
+				keyID:       "",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+					{
+						Use: "enc",
+						Key: &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{
+					Use: "sig",
+					Key: &rsa.PublicKey{},
+				},
+				err: nil,
+			},
+		},
+		{
+			"multiple keys no kid, jwt with kid, ErrKeyMultiple",
+			args{
+				keyID:       "id",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{},
+				err: ErrKeyMultiple,
+			},
+		},
+		{
+			"multiple keys with kid, jwt with kid, match",
+			args{
+				keyID:       "id1",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use:   "sig",
+						KeyID: "id1",
+						Key:   &rsa.PublicKey{},
+					},
+					{
+						Use:   "sig",
+						KeyID: "id2",
+						Key:   &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{
+					Use:   "sig",
+					KeyID: "id1",
+					Key:   &rsa.PublicKey{},
+				},
+				err: nil,
+			},
+		},
+		{
+			"multiple keys, single sig key, jwt with kid, match",
+			args{
+				keyID:       "id1",
+				use:         KeyUseSignature,
+				expectedAlg: "RS256",
+				keys: []jose.JSONWebKey{
+					{
+						Use: "sig",
+						Key: &rsa.PublicKey{},
+					},
+					{
+						Use: "enc",
+						Key: &rsa.PublicKey{},
+					},
+				},
+			},
+			res{
+				key: jose.JSONWebKey{
+					Use: "sig",
+					Key: &rsa.PublicKey{},
+				},
+				err: nil,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := FindMatchingKey(tt.args.keyID, tt.args.use, tt.args.expectedAlg, tt.args.keys...)
+			if (tt.res.err != nil && !errors.Is(err, tt.res.err)) || (tt.res.err == nil && err != nil) {
+				t.Errorf("FindKey() error, got = %v, want = %v", err, tt.res.err)
+			}
+			if !reflect.DeepEqual(got, tt.res.key) {
+				t.Errorf("FindKey() got = %v, want %v", got, tt.res.key)
+			}
+		})
+	}
+}
diff --git a/pkg/oidc/verifier.go b/pkg/oidc/verifier.go
index f8470b5..4284d17 100644
--- a/pkg/oidc/verifier.go
+++ b/pkg/oidc/verifier.go
@@ -39,6 +39,7 @@ var (
 	ErrSignatureMultiple       = errors.New("id_token contains multiple signatures")
 	ErrSignatureUnsupportedAlg = errors.New("signature algorithm not supported")
 	ErrSignatureInvalidPayload = errors.New("signature does not match Payload")
+	ErrSignatureInvalid        = errors.New("invalid signature")
 	ErrExpired                 = errors.New("token has expired")
 	ErrIatMissing              = errors.New("issuedAt of token is missing")
 	ErrIatInFuture             = errors.New("issuedAt of token is in the future")
@@ -143,7 +144,7 @@ func CheckSignature(ctx context.Context, token string, payload []byte, claims Cl
 
 	signedPayload, err := set.VerifySignature(ctx, jws)
 	if err != nil {
-		return err
+		return fmt.Errorf("%w (%v)", ErrSignatureInvalid, err)
 	}
 
 	if !bytes.Equal(signedPayload, payload) {
diff --git a/pkg/op/config.go b/pkg/op/config.go
index 704cc20..39c84c8 100644
--- a/pkg/op/config.go
+++ b/pkg/op/config.go
@@ -4,7 +4,6 @@ import (
 	"errors"
 	"net/url"
 	"os"
-	"strings"
 
 	"golang.org/x/text/language"
 )
@@ -57,9 +56,5 @@ func devLocalAllowed(url *url.URL) bool {
 	if !b {
 		return b
 	}
-	return url.Scheme == "http" &&
-		url.Host == "localhost" ||
-		url.Host == "127.0.0.1" ||
-		url.Host == "::1" ||
-		strings.HasPrefix(url.Host, "localhost:")
+	return url.Scheme == "http"
 }
diff --git a/pkg/op/op.go b/pkg/op/op.go
index e10a088..419a9b9 100644
--- a/pkg/op/op.go
+++ b/pkg/op/op.go
@@ -2,7 +2,7 @@ package op
 
 import (
 	"context"
-	"errors"
+	"fmt"
 	"net/http"
 	"time"
 
@@ -279,12 +279,12 @@ type openIDKeySet struct {
 func (o *openIDKeySet) VerifySignature(ctx context.Context, jws *jose.JSONWebSignature) ([]byte, error) {
 	keySet, err := o.Storage.GetKeySet(ctx)
 	if err != nil {
-		return nil, errors.New("error fetching keys")
+		return nil, fmt.Errorf("error fetching keys: %w", err)
 	}
 	keyID, alg := oidc.GetKeyIDAndAlg(jws)
-	key, ok := oidc.FindKey(keyID, oidc.KeyUseSignature, alg, keySet.Keys...)
-	if !ok {
-		return nil, errors.New("invalid kid")
+	key, err := oidc.FindMatchingKey(keyID, oidc.KeyUseSignature, alg, keySet.Keys...)
+	if err != nil {
+		return nil, fmt.Errorf("invalid signature: %w", err)
 	}
 	return jws.Verify(&key)
 }