diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
new file mode 100644
index 0000000..1131471
--- /dev/null
+++ b/.github/workflows/ruby.yml
@@ -0,0 +1,37 @@
+# This workflow uses actions that are not certified by GitHub.
+# They are provided by a third-party and are governed by
+# separate terms of service, privacy policy, and support
+# documentation.
+# This workflow will download a prebuilt Ruby version, install dependencies and run tests with Rake
+# For more information see: https://github.com/marketplace/actions/setup-ruby-jruby-and-truffleruby
+
+name: Ruby
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ruby-version: ['2.7', '3.0']
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Ruby
+    # To automatically get bug fixes and new Ruby versions for ruby/setup-ruby,
+    # change this to (see https://github.com/ruby/setup-ruby#versioning):
+      uses: ruby/setup-ruby@v1 # v1.146.0
+      with:
+        ruby-version: ${{ matrix.ruby-version }}
+        bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+    - name: Run tests
+      run: bundle exec rake
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index b6e28c4..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,12 +0,0 @@
-sudo: false
-language: ruby
-rvm:
-  - 2.6.6
-  - 2.7.2
-  - 3.0.0
-before_install:
-  - sudo apt-get update
-  - sudo apt-get install -y libsodium-dev
-  - gem update --system
-  - gem --version
-  - gem install bundler
diff --git a/README.md b/README.md
index a081da0..83d8c0f 100644
--- a/README.md
+++ b/README.md
@@ -1,11 +1,5 @@
 # threema
 
-[![Build Status](https://travis-ci.org/thorsteneckel/threema.svg?branch=master)](https://travis-ci.org/thorsteneckel/threema)
-[![codecov](https://codecov.io/gh/thorsteneckel/threema/branch/master/graph/badge.svg)](https://codecov.io/gh/thorsteneckel/threema)
-[![Code Climate](https://codeclimate.com/github/thorsteneckel/threema/badges/gpa.svg)](https://codeclimate.com/github/thorsteneckel/threema)
-[![Gem](https://img.shields.io/gem/v/threema.svg?maxAge=2592000)]()
-
-
 This gem provides access to the Threema Gateway API.
 
 ## Installation
diff --git a/lib/threema/blob.rb b/lib/threema/blob.rb
index 5d98281..b3bd3cc 100644
--- a/lib/threema/blob.rb
+++ b/lib/threema/blob.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'case_transform'
 require 'threema/exceptions'
 
 class Threema
diff --git a/lib/threema/capabilities.rb b/lib/threema/capabilities.rb
index c5b1305..e12d486 100644
--- a/lib/threema/capabilities.rb
+++ b/lib/threema/capabilities.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'case_transform'
-
 class Threema
   class Capabilities
     class << self
diff --git a/lib/threema/lookup.rb b/lib/threema/lookup.rb
index 956a0e4..9baab6e 100644
--- a/lib/threema/lookup.rb
+++ b/lib/threema/lookup.rb
@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require 'case_transform'
-
 class Threema
   class Lookup
     URL_PATH = {
@@ -67,7 +65,7 @@ def bulk(params)
     def keys_camel_lower(params)
       cameled = {}
       params.each do |key, value|
-        cameled[CaseTransform.camel_lower(key.to_s)] = value
+        cameled[key.to_s.camelize(:lower)] = value
       end
       cameled
     end
@@ -76,7 +74,7 @@ def underscore_entry_keys(list)
       list.collect do |response_entry|
         result_entry = {}
         response_entry.each do |key, value|
-          result_entry[CaseTransform.underscore(key).to_sym] = value
+          result_entry[key.underscore.to_sym] = value
         end
 
         result_entry
diff --git a/lib/threema/receive.rb b/lib/threema/receive.rb
index 2d1e874..4cca456 100644
--- a/lib/threema/receive.rb
+++ b/lib/threema/receive.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'case_transform'
 require 'threema/e2e/mac'
 require 'threema/typed_message'
 require 'threema/lookup'
@@ -65,7 +64,7 @@ def classify(type)
       end
 
       def class_name(type)
-        class_name = CaseTransform.camel(type.to_s)
+        class_name = type.to_s.camelize
         "Threema::Receive::#{class_name}"
       end
 
diff --git a/lib/threema/send.rb b/lib/threema/send.rb
index 19f876f..954632f 100644
--- a/lib/threema/send.rb
+++ b/lib/threema/send.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'case_transform'
 require 'threema/exceptions'
 require 'threema/send/simple'
 require 'threema/send/text'
diff --git a/spec/factories/threema.rb b/spec/factories/threema.rb
index 7535db8..9c9e2ce 100644
--- a/spec/factories/threema.rb
+++ b/spec/factories/threema.rb
@@ -4,6 +4,7 @@
   factory :threema do
     api_identity { test_from }
     api_secret   { test_api_secret }
+    private_key { test_private_key }
 
     initialize_with do
       new(**attributes)
diff --git a/spec/factories/threema_client.rb b/spec/factories/threema_client.rb
index ff24ee7..d572fc4 100644
--- a/spec/factories/threema_client.rb
+++ b/spec/factories/threema_client.rb
@@ -2,7 +2,7 @@
 
 FactoryBot.define do
   factory :threema_client, class: Threema::Client do
-    threema { FactoryBot.build(:threema) }
+    threema
 
     initialize_with do
       new(**attributes)
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 055d526..347d6b1 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -10,19 +10,13 @@
 require 'pry'
 
 require 'simplecov'
-require 'codecov'
-require 'codeclimate-test-reporter'
 
 SimpleCov.start do
   # Don't get coverage on the test cases themselves.
   add_filter '/spec/'
   add_filter '/test/'
-  # Codecov doesn't automatically ignore vendored files.
-  add_filter '/vendor/'
 end
-SimpleCov.formatter = SimpleCov::Formatter::Codecov
-
-CodeClimate::TestReporter.start
+SimpleCov.formatter = SimpleCov::Formatter::HTMLFormatter
 
 require 'threema'
 
diff --git a/spec/support/shared_values.rb b/spec/support/shared_values.rb
index dc6b355..61af51b 100644
--- a/spec/support/shared_values.rb
+++ b/spec/support/shared_values.rb
@@ -9,11 +9,11 @@ def hello_world
 end
 
 def test_public_key
-  ENV['THREEMARB_PUBLIC']
+  'd981f35570026a9551fbb27709087fe9c268b8f1395998b4ae5019476cd58fae'
 end
 
 def test_private_key
-  ENV['THREEMARB_PRIVATE']
+  '2edf856e8a0f8f8e761be57f895f8827f42c6be0c6c891b95494faa7d264f7d9'
 end
 
 def test_auth_params
@@ -24,11 +24,11 @@ def test_auth_params
 end
 
 def test_from
-  ENV['THREEMARB_API_IDENTITY']
+  '*VALID1'
 end
 
 def test_api_secret
-  ENV['THREEMARB_API_SECRET']
+  'CWWuNaFDkEZLiRSt'
 end
 
 def test_blob_id
diff --git a/spec/threema/client_spec.rb b/spec/threema/client_spec.rb
index 0a7d4d0..0e65d0c 100644
--- a/spec/threema/client_spec.rb
+++ b/spec/threema/client_spec.rb
@@ -11,8 +11,8 @@
     expect(described_class).to respond_to(:url)
   end
 
-  let(:instance) { build(:threema_client, threema: threema) }
-  let(:threema) { build(:threema) }
+  let(:instance) { build(:threema_client) }
+  let!(:threema) { build(:threema) }
 
   context '#not_found_ok' do
     it 'responds to not_found_ok' do
@@ -53,8 +53,8 @@
 
       before(:each) do
         instance.configure do |config|
-          # Threema API fingerprint as of 2021-02-27
-          fingerprint = '42b1038e72f00c8c4dad78a3ebdc6d7a50c5ef288da9019b9171e4d675c08a17'
+          # Threema API fingerprint as of 2024-04-30
+          fingerprint = '317bc8626c34a2ccd9052164828f4eb71a6bc6290e2569acee5b3a2cbde13d2a'
 
           # See: http://stackoverflow.com/a/22108461
           config.use_ssl = true
@@ -74,8 +74,8 @@
         end
       end
 
-      # this is needed due to internet access restrictions
-      # in the (travis) CI environment
+      # skipped in CI because this test requires actual
+      # private key, identity, etc set in .env variables
       if !ENV['CI']
         context 'given Threema Message API URL with matching certificate' do
           let(:url) { described_class::API_URL }
@@ -87,7 +87,7 @@
       end
 
       context 'given another URL without matching certificate' do
-        let(:url) { 'https://github.com/thorsteneckel/threema' }
+        let(:url) { 'https://github.com/threemarb/threema' }
         it { should raise_error(OpenSSL::SSL::SSLError) }
 
         context 'but if static certificate pinning is disabled' do
diff --git a/threema.gemspec b/threema.gemspec
index 38ff347..9f38b4b 100644
--- a/threema.gemspec
+++ b/threema.gemspec
@@ -16,12 +16,12 @@ Gem::Specification.new do |spec|
   spec.homepage      = 'https://github.com/thorsteneckel/threema'
   spec.license       = 'MIT'
 
-  spec.required_ruby_version = '>= 2.6.0'
+  spec.required_ruby_version = '>= 2.7.0'
 
   spec.files         = Dir['{lib}/**/*']
   spec.require_paths = ['lib']
 
-  spec.add_runtime_dependency 'case_transform'
+  spec.add_runtime_dependency 'activesupport', '~> 7.0.8'
   spec.add_runtime_dependency 'dotenv'
   spec.add_runtime_dependency 'mimemagic'
   spec.add_runtime_dependency 'mime-types'
@@ -29,8 +29,6 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'rbnacl'
 
   spec.add_development_dependency 'bundler'
-  spec.add_development_dependency 'codeclimate-test-reporter', '~> 0.6'
-  spec.add_development_dependency 'codecov'
   spec.add_development_dependency 'factory_bot'
   spec.add_development_dependency 'fakefs'
   spec.add_development_dependency 'pry'