diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..f2e41f5
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,47 @@
+AllCops:
+  DisplayCopNames: true
+  NewCops: disable
+  TargetRubyVersion: 3.3.6
+
+Style/FrozenStringLiteralComment:
+  Exclude:
+    - 'lib/acquia-http-hmac/rack_authenticate.rb'
+
+Metrics/ParameterLists:
+  Max: 7
+
+Style/ClassVars:
+  Exclude:
+    - 'example/app.rb'
+    - 'lib/acquia-http-hmac/rack_authenticate.rb'
+
+Metrics/AbcSize:
+  Max: 50
+  Exclude:
+    - 'test/acquia_spec_test.rb'
+
+Naming/AccessorMethodName:
+  Exclude:
+    - 'test/rack_simple_app_test.rb'
+    - 'test/rack_sqlite3_app_test.rb'
+
+Metrics/BlockLength:
+  Max: 150
+
+Metrics/ClassLength:
+  Max: 1000
+
+Metrics/CyclomaticComplexity:
+  Max: 12
+
+Layout/LineLength:
+  Max: 200
+
+Metrics/MethodLength:
+  Max: 50
+
+Metrics/ModuleLength:
+  Max: 250
+
+Metrics/PerceivedComplexity:
+  Max: 10
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 71d2c2b..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,11 +0,0 @@
-language: ruby
-rvm:
-  - "2.6"
-  - "2.7"
-  - "3.0"
-before_script:
- - "bundle exec rackup -p8010 example/config.ru &"
- - "sleep 3"
-script:
- - "bundle exec rake test"
- - "example/test.sh"
diff --git a/Gemfile b/Gemfile
index b4e2a20..7f4f5e9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
-source "https://rubygems.org"
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
 
 gemspec
diff --git a/Rakefile b/Rakefile
index 70a4928..bb52302 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,12 +1,21 @@
+# frozen_string_literal: true
+
 require 'bundler/setup'
 
 begin
   require 'rake/testtask'
   Rake::TestTask.new do |t|
-    t.libs.push "lib"
+    t.libs.push 'lib'
     t.test_files = FileList['test/*_test.rb']
     t.verbose = true
   end
-  task(default: [:test])
-rescue LoadError
+
+  desc 'Run RuboCop'
+  task :rubocop do
+    sh 'rubocop'
+  end
+
+  task default: %i[test rubocop]
+rescue LoadError => e
+  warn "Could not load rake/testtask: #{e}"
 end
diff --git a/acquia-http-hmac.gemspec b/acquia-http-hmac.gemspec
index a6b02de..dc911d6 100644
--- a/acquia-http-hmac.gemspec
+++ b/acquia-http-hmac.gemspec
@@ -1,24 +1,29 @@
+# frozen_string_literal: true
+
 Gem::Specification.new do |s|
   s.name = 'acquia-http-hmac'
-  s.version = '2.0.2'
+  s.version = '2.0.3'
+  s.required_ruby_version = '>= 3.3.0'
   s.licenses = ['MIT']
-  s.summary = "HMAC signing library and rack middleware"
+  s.summary = 'HMAC signing library and rack middleware'
   s.description = "HMAC signing library and rack middleware conforming to Acquia's HMAC 2.0 specifications"
-  s.date = Time.now.strftime("%Y-%m-%d")
-  s.authors = ["Peter Wolanin", "Marc Seeger"]
+  s.date = Time.now.strftime('%Y-%m-%d')
+  s.authors = ['Peter Wolanin', 'Marc Seeger']
   s.email = 'engineering@acquia.com'
-  s.homepage    = 'https://www.acquia.com/'
-  s.files = Dir["[A-Z]*", "{bin,etc,lib,test}/**/*"]
+  s.homepage = 'https://www.acquia.com/'
+  s.files = Dir['[A-Z]*', '{bin,etc,lib,test}/**/*']
   s.bindir = 'bin'
-  s.require_paths = ["lib"]
+  s.require_paths = ['lib']
   s.executables << 'acq-http-request'
 
-  s.add_dependency 'addressable', '~> 2.4'
+  s.add_dependency 'addressable', '~> 2.8'
 
-  s.add_development_dependency('rake')
-  s.add_development_dependency('grape')
-  s.add_development_dependency('rack-test')
-  s.add_development_dependency('multi_json')
-  s.add_development_dependency('sqlite3')
-  s.add_development_dependency('webrick')
+  s.add_development_dependency('grape', '~> 2.2')
+  s.add_development_dependency('multi_json', '~> 1.15')
+  s.add_development_dependency 'rack', '~> 2.2.10'
+  s.add_development_dependency('rack-test', '~> 2.1')
+  s.add_development_dependency('rake', '~> 13.2')
+  s.add_development_dependency 'rubocop', '~> 1.69'
+  s.add_development_dependency('sqlite3', '~> 2.4')
+  s.add_development_dependency('webrick', '~> 1.9')
 end
diff --git a/bin/acq-http-request b/bin/acq-http-request
index ab7ff42..d132b62 100755
--- a/bin/acq-http-request
+++ b/bin/acq-http-request
@@ -1,79 +1,71 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
 require 'acquia-http-hmac'
 require 'optparse'
 require 'ostruct'
 
-if ARGV[0]
-  url = ARGV[0]
-end
+url = ARGV[0] if ARGV[0]
 
 # Argument processing
 options = OpenStruct.new
 options.realm = 'Test'
 options.http_method = 'GET'
 o = OptionParser.new do |opts|
-  opts.banner = "Usage: #{$0} URL -u ID:PASSWORD"
-  opts.on("-r", "--realm [REALM]", "Server auth realm. Default 'Test'.") { |v| options.realm = v }
-  opts.on("-u", "--user [ID:PASSWORD]", "HMAC creds") { |v| options.user = v }
-  opts.on("-d", "--data [DATA]", "Data to POST.") { |v| options.data = v }
-  opts.on("-X", "--request [METHOD]", "HTTP method.  Defaults to GET, or POST if --data is specified.") { |v| options.http_method = v.upcase }
+  opts.banner = "Usage: #{$PROGRAM_NAME} URL -u ID:PASSWORD"
+  opts.on('-r', '--realm [REALM]', "Server auth realm. Default 'Test'.") { |v| options.realm = v }
+  opts.on('-u', '--user [ID:PASSWORD]', 'HMAC creds') { |v| options.user = v }
+  opts.on('-d', '--data [DATA]', 'Data to POST.') { |v| options.data = v }
+  opts.on('-X', '--request [METHOD]', 'HTTP method.  Defaults to GET, or POST if --data is specified.') { |v| options.http_method = v.upcase }
 end
 begin
   o.parse!
-rescue Exception => e
+rescue StandardError => e
   puts e.message
   puts o.help
   exit 1
 end
 
-if ARGV.empty? or !options.user
+if ARGV.empty? || !options.user
   puts o.help
   exit
 end
 
 uri = URI(Addressable::URI.escape.encode(url))
 
-if uri.path == ''
-  uri.path = '/'
-end
+uri.path = '/' if uri.path == ''
 
 host = uri.host
-if uri.port && uri.port != '443'
-  host << ':' + uri.port
-end
+host << ":#{uri.port}" if uri.port && uri.port != '443'
 
 id, password = options.user.split(':', 2)
 
 mac = Acquia::HTTPHmac::Auth.new(options.realm, password)
 
-
-
 args = {
   http_method: options.http_method,
   host: host,
   id: id,
-  path_info: uri.path,
+  path_info: uri.path
 }
 
-case
-when options.http_method == 'GET'
-  req = Net::HTTP::GET.new(uri)
-when options.http_method == 'HEAD'
-  req = Net::HTTP::HEAD.new(uri)
-when options.http_method == 'POST'
-  req = Net::HTTP::POST.new(uri)
-when options.http_method == 'PUT'
-  req = Net::HTTP::PUT.new(uri)
-when options.http_method == 'DELETE'
-  req = Net::HTTP::DELETE.new(uri)
+case options.http_method
+when 'GET'
+  Net::HTTP::GET.new(uri)
+when 'HEAD'
+  Net::HTTP::HEAD.new(uri)
+when 'POST'
+  Net::HTTP::POST.new(uri)
+when 'PUT'
+  Net::HTTP::PUT.new(uri)
+when 'DELETE'
+  Net::HTTP::DELETE.new(uri)
 else
-  fail("Unsupported HTTP verb #{options.http_method}")
+  raise("Unsupported HTTP verb #{options.http_method}")
 end
 mac.prepare_request_headers(args).each do |name, value|
-  #header(name, value)
+  # header(name, value)
 end
 
 net = Net::HTTP.new(uri.host, uri.port)
-net.use_ssl= uri.host != 'localhost'
-
+net.use_ssl = uri.host != 'localhost'
diff --git a/example-sqlite3/setup.rb b/example-sqlite3/setup.rb
index 283e4d2..89ad837 100644
--- a/example-sqlite3/setup.rb
+++ b/example-sqlite3/setup.rb
@@ -1,11 +1,12 @@
+# frozen_string_literal: true
+
 require 'sqlite3'
 require 'base64'
 require 'openssl'
 require 'yaml'
 
-
+# Class: ExampleSQLite3Setup
 class ExampleSQLite3Setup
-
   def initialize(dbfile, passwords_file)
     @dbfile = dbfile
     File.unlink(@dbfile) if File.exist?(@dbfile)
@@ -13,7 +14,7 @@ def initialize(dbfile, passwords_file)
   end
 
   def create_t1
-    return <<-SQL
+    <<-SQL
       CREATE TABLE passwords (
         id VARCHAR(50),
         request_date CHAR(10),
@@ -24,7 +25,7 @@ def create_t1
   end
 
   def create_t2
-    return <<-SQL
+    <<-SQL
       CREATE TABLE password_data (
         id VARCHAR(50),
         request_method VARCHAR(10),
@@ -46,43 +47,43 @@ def write_database
 
     dates =  [
       today.strftime('%F'),
-      tomorrow.strftime('%F'),
+      tomorrow.strftime('%F')
     ]
     realm = 'Test'
 
     creds = YAML.safe_load(File.read(@passwords_file))
     passwords = {}
-    creds.each do |id,data|
+    creds.each do |id, data|
       passwords[id] = data['password']
     end
 
     data = {
       'testadmin' => [
         ['GET', '/'],
-        ['POST', '/'],
+        ['POST', '/']
       ],
       'testuser' => [],
       'curltest' => [
-        ['GET', '/'],
-      ],
+        ['GET', '/']
+      ]
     }
 
-    sha256 = OpenSSL::Digest::SHA256.new
+    sha256 = OpenSSL::Digest.new('SHA256')
 
-    passwords.each do |id,pass|
+    passwords.each do |id, pass|
       # Run a 2-step HMAC KDF using date and realm
       binary_pass = Base64.decode64(pass)
       dates.each do |date|
         derived_pass1 = OpenSSL::HMAC.digest(sha256, binary_pass, date)
         derived_pass2 = OpenSSL::HMAC.digest(sha256, derived_pass1, realm)
-        db.execute("INSERT INTO passwords (id, request_date, base64_password) VALUES ( ?, ?, ? )", [id, date, Base64.strict_encode64(derived_pass2)])
+        db.execute('INSERT INTO passwords (id, request_date, base64_password) VALUES ( ?, ?, ? )', [id, date, Base64.strict_encode64(derived_pass2)])
       end
     end
 
     data.each do |id, values|
       values.each do |row|
-         row.unshift(id)
-         db.execute("INSERT INTO password_data VALUES ( ?, ?, ? )", row)
+        row.unshift(id)
+        db.execute('INSERT INTO password_data VALUES ( ?, ?, ? )', row)
       end
     end
 
@@ -90,7 +91,7 @@ def write_database
   end
 end
 
-if $0 == __FILE__
+if $PROGRAM_NAME == __FILE__
 
   mypath = File.dirname(__FILE__)
   dbfile = File.join(mypath, 'passwords.sqlite3')
diff --git a/example/app.rb b/example/app.rb
index ea18329..7615f8d 100644
--- a/example/app.rb
+++ b/example/app.rb
@@ -1,9 +1,12 @@
+# frozen_string_literal: true
+
 require 'bundler/setup'
 require 'securerandom'
 require 'grape'
 require 'json'
 
 module Example
+  # Class: App
   class App < Grape::API
     version 'v1', using: :header, vendor: 'acquia'
 
@@ -14,28 +17,28 @@ class App < Grape::API
     helpers do
       def hellos
         # Store data in memory for simple testing.
-        @@hellos ||= {SecureRandom.uuid => "world"}
+        @@hellos ||= { SecureRandom.uuid => 'world' }
         @@hellos
       end
     end
 
     resource :hello do
       get do
-        {hello: hellos}
+        { hello: hellos }
       end
 
-      desc "Return a single hello."
+      desc 'Return a single hello.'
       get ':id' do
-        {hello: hellos[params[:id]]}
+        { hello: hellos[params[:id]] }
       end
 
       params do
-        requires :hello, type: String, desc: "A hello."
+        requires :hello, type: String, desc: 'A hello.'
       end
       post do
         id = SecureRandom.uuid
         hellos[id] = params[:hello]
-        {id => params[:hello]}
+        { id => params[:hello] }
       end
     end
 
diff --git a/example/config.ru b/example/config.ru
index 73682bc..42d20fb 100755
--- a/example/config.ru
+++ b/example/config.ru
@@ -1,18 +1,19 @@
 #!/usr/bin/env rackup -p8010
+# frozen_string_literal: true
 
-require "bundler/setup"
+require 'bundler/setup'
 Bundler.require
 
 require_relative 'app'
 require 'acquia-http-hmac/rack_authenticate'
 
 unless ENV['NO_AUTHENTICATION']
-  passwords = Acquia::HTTPHmac::FilePasswordStorage.new(File.dirname(__FILE__) + '/../fixtures/passwords.yml')
+  passwords = Acquia::HTTPHmac::FilePasswordStorage.new("#{File.dirname(__FILE__)}/../fixtures/passwords.yml")
   options = {
     password_storage: passwords,
     realm: 'Test',
     nonce_checker: Acquia::HTTPHmac::MemoryNonceChecker.new,
-    excluded_paths: ['/healthcheck'],
+    excluded_paths: ['/healthcheck']
   }
   use Acquia::HTTPHmac::RackAuthenticate, options
 end
diff --git a/features/step_definitions/common.rb b/features/step_definitions/common.rb
index 5a8df97..f2930ca 100644
--- a/features/step_definitions/common.rb
+++ b/features/step_definitions/common.rb
@@ -1,40 +1,41 @@
-Given /^the endpoint "(.*?)" "(.*?)"$/ do |method, path|
-	@method = method
-	@path = path
+# frozen_string_literal: true
+
+Given(/^the endpoint "(.*?)" "(.*?)"$/) do |method, path|
+  @method = method
+  @path = path
 end
 
-Given /^the header "(.*?)" "(.*?)"$/ do |key, value|
-	@headers = Hash.new unless @headers
-	@headers[key] = value
+Given(/^the header "(.*?)" "(.*?)"$/) do |key, value|
+  @headers ||= {}
+  @headers[key] = value
 end
 
-Given /^the custom header "(.*?)" "(.*?)"$/ do |key, value|
-	@cheaders = Hash.new unless @cheaders
-	@cheaders[key] = value
-	@headers = Hash.new unless @headers
-	@headers[key] = value
+Given(/^the custom header "(.*?)" "(.*?)"$/) do |key, value|
+  @cheaders ||= {}
+  @cheaders[key] = value
+  @headers ||= {}
+  @headers[key] = value
 end
 
-Given /^the body "(.*?)"$/ do |body|
-	@body = body
+Given(/^the body "(.*?)"$/) do |body|
+  @body = body
 end
 
-When /^I sign the request with the "(.*?)" digest and secret key "(.*?)"$/ do |digest, key|
-	signer = Acquia::HTTPHmac.new(@method, @body, @headers, @cheaders, @path)
-	key = key
-	case digest
-	when "SHA-1"
-		digester = Digest::SHA1
-	when "SHA1"
-		digester = Digest::SHA1
-	when "SHA-256"
-		digester = Digest::SHA256
-	when "SHA256"
-		digester = Digest::SHA256
-	end
-	@signature = signer.sign(digester, key)
+When(/^I sign the request with the "(.*?)" digest and secret key "(.*?)"$/) do |digest, key|
+  signer = Acquia::HTTPHmac.new(@method, @body, @headers, @cheaders, @path)
+  case digest
+  when 'SHA-1'
+    digester = Digest::SHA1
+  when 'SHA1'
+    digester = Digest::SHA1
+  when 'SHA-256'
+    digester = Digest::SHA256
+  when 'SHA256'
+    digester = Digest::SHA256
+  end
+  @signature = signer.sign(digester, key)
 end
 
-Then /^I should see the signature "(.*?)"$/ do |signature|
-	expect(@signature).to eq(signature)
-end
\ No newline at end of file
+Then(/^I should see the signature "(.*?)"$/) do |signature|
+  expect(@signature).to eq(signature)
+end
diff --git a/features/support/env.rb b/features/support/env.rb
index d86c6f3..462ae14 100644
--- a/features/support/env.rb
+++ b/features/support/env.rb
@@ -1 +1,3 @@
-require 'acquia/httphmac'
\ No newline at end of file
+# frozen_string_literal: true
+
+require 'acquia/httphmac'
diff --git a/lib/acquia-http-hmac/rack_authenticate.rb b/lib/acquia-http-hmac/rack_authenticate.rb
index 148982d..e75f0de 100644
--- a/lib/acquia-http-hmac/rack_authenticate.rb
+++ b/lib/acquia-http-hmac/rack_authenticate.rb
@@ -1,10 +1,11 @@
 require 'yaml'
 require 'openssl'
 require 'base64'
-require_relative '../acquia-http-hmac'
+require_relative '../acquia_http_hmac'
 
 module Acquia
   module HTTPHmac
+    # Class: RackAuthenticate
     class RackAuthenticate
       def initialize(app, options)
         @password_storage = options[:password_storage]
@@ -16,17 +17,17 @@ def initialize(app, options)
 
       def call(env)
         # Skip paths based on a list of prefixes.
-        if @excluded_paths && env['PATH_INFO'].start_with?(*@excluded_paths)
-          return @app.call(env)
-        end
+        return @app.call(env) if @excluded_paths && env['PATH_INFO'].start_with?(*@excluded_paths)
+
         auth_header = env['HTTP_AUTHORIZATION'].to_s
         return unauthorized if auth_header.empty?
 
         attributes = Acquia::HTTPHmac::Auth.parse_auth_header(auth_header)
         return denied('Invalid nonce') unless @nonce_checker.valid?(attributes[:id], attributes[:nonce])
+
         args = args_for_authenticator(env, attributes)
         mac = message_authenticator(args[:id], args[:timestamp])
-        return denied('Invalid credentials') unless mac && mac.request_authenticated?(args)
+        return denied('Invalid credentials') unless mac&.request_authenticated?(args)
 
         return denied('Invalid body') unless valid_body?(env)
 
@@ -40,31 +41,27 @@ def call(env)
       private
 
       def unauthorized
-        [ 401,
-          {
-            'Content-Type' => 'text/plain',
-            'Content-Length' => '0',
-            'WWW-Authenticate' => 'acquia-http-hmac realm="'+ @realm +'"'
-          },
-          []
-        ]
+        [401,
+         {
+           'Content-Type' => 'text/plain',
+           'Content-Length' => '0',
+           'WWW-Authenticate' => "acquia-http-hmac realm=\"#{@realm}\""
+         },
+         []]
       end
 
       def denied(message)
-        [ 403,
-          {
-            'Content-Type' => 'text/plain',
-            'Connection' => 'close',
-          },
-          [message]
-        ]
+        [403,
+         {
+           'Content-Type' => 'text/plain',
+           'Connection' => 'close'
+         },
+         [message]]
       end
 
       def message_authenticator(id, timestamp)
         mac = nil
-        if @password_storage.valid?(id)
-          mac = Acquia::HTTPHmac::Auth.new(@realm, @password_storage.password(id, timestamp))
-        end
+        mac = Acquia::HTTPHmac::Auth.new(@realm, @password_storage.password(id, timestamp)) if @password_storage.valid?(id)
         mac
       end
 
@@ -77,11 +74,11 @@ def args_for_authenticator(env, attributes)
           path_info: request.path_info,
           content_type: request.content_type,
           body_hash: env['HTTP_X_AUTHORIZATION_CONTENT_SHA256'],
-          timestamp: env['HTTP_X_AUTHORIZATION_TIMESTAMP'].to_i,
+          timestamp: env['HTTP_X_AUTHORIZATION_TIMESTAMP'].to_i
         }.merge(attributes)
         # Map expected header names to the key that would be in env.
-        attributes[:headers].keys.each do |name|
-          key = 'HTTP_' + name.gsub('-', '_').upcase
+        attributes[:headers].each_key do |name|
+          key = "HTTP_#{name.gsub('-', '_').upcase}"
           args[:headers][name] = env[key] if env[key]
         end
         args
@@ -116,18 +113,17 @@ def sign_response(status, headers, resp_body, nonce, timestamp, mac)
         # Rack defines the response body as implementing #each
         resp_body.each { |part| final_body << part }
         # Use the request nonce to sign the response.
-        headers['X-Server-Authorization-HMAC-SHA256'] = mac.signature(nonce + "\n" + timestamp.to_s + "\n" + final_body)
+        headers['X-Server-Authorization-HMAC-SHA256'] = mac.signature("#{nonce}\n#{timestamp}\n#{final_body}")
         # Nobody should be changing or caching this response.
         headers['Cache-Control'] = 'no-transform, no-cache, no-store, private, max-age=0'
         [status, headers, [final_body]]
       end
-
     end
 
     ### The classes below are primarily for testing.
 
+    # Class: SimplePasswordStorage
     class SimplePasswordStorage
-
       def initialize(creds = {})
         @@creds = creds
       end
@@ -143,13 +139,15 @@ def valid?(id)
       # @param [Integer] timestamp
       #   A unix timestamp. The returned password may be different based on
       #   the current date or time.
-      def password(id, timestamp)
-        fail('Invalid id') unless @@creds[id] && @@creds[id]['password']
+      def password(id, _timestamp)
+        raise('Invalid id') unless @@creds[id] && @@creds[id]['password']
+
         @@creds[id]['password']
       end
 
       def data(id)
-        fail('Invalid id') unless @@creds[id]
+        raise('Invalid id') unless @@creds[id]
+
         @@creds[id]
       end
 
@@ -158,23 +156,23 @@ def ids
       end
     end
 
+    # Class: FilePasswordStorage
     class FilePasswordStorage < SimplePasswordStorage
-
       def initialize(filename)
         creds = {}
-        if File.exist?(filename)
-          creds = YAML.safe_load(File.read(filename))
-        end
+        creds = YAML.safe_load(File.read(filename)) if File.exist?(filename)
         super(creds)
       end
     end
 
+    # Class: NoopNonceChecker
     class NoopNonceChecker
-      def valid?(id, nonce)
+      def valid?(_id, nonce)
         nonce.length == 36
       end
     end
 
+    # Class: MemoryNonceChecker
     class MemoryNonceChecker
       def initialize
         @@seen = {}
@@ -183,6 +181,7 @@ def initialize
       def valid?(id, nonce)
         # A UUID is 36 characters.
         return false unless nonce.length == 36
+
         @@seen[id] ||= {}
         valid = !@@seen[id][nonce]
         @@seen[id][nonce] = Time.now.to_i
@@ -191,4 +190,3 @@ def valid?(id, nonce)
     end
   end
 end
-
diff --git a/lib/acquia-http-hmac/sqlite3_password_storage.rb b/lib/acquia-http-hmac/sqlite3_password_storage.rb
index 6e57a23..219f6ce 100644
--- a/lib/acquia-http-hmac/sqlite3_password_storage.rb
+++ b/lib/acquia-http-hmac/sqlite3_password_storage.rb
@@ -1,12 +1,13 @@
+# frozen_string_literal: true
+
 require 'openssl'
 require 'base64'
 require 'sqlite3'
 
 module Acquia
   module HTTPHmac
-
+    # Class: SQLite3PasswordStorage
     class SQLite3PasswordStorage
-
       def initialize(filename)
         @filename = filename
         @creds = {}
@@ -25,13 +26,15 @@ def valid?(id)
       #   A unix timestamp. The returned password may be different based on
       #   the current date or time.
       def password(id, timestamp)
-        fail('Invalid id') unless valid?(id)
+        raise('Invalid id') unless valid?(id)
+
         load(id, timestamp.to_i)
         @creds[id]['password']
       end
 
       def data(id)
-        fail('Invalid id') unless valid?(id)
+        raise('Invalid id') unless valid?(id)
+
         result = []
         connection.execute('SELECT * FROM password_data WHERE id = ?', [today]) do |row|
           result << row
@@ -51,17 +54,17 @@ def ids
 
       def load(id, timestamp = nil)
         date = timestamp ? Time.at(timestamp).utc.strftime('%F') : today
-        if @creds[id].nil? || date != today
-          @creds[id] = false
-          connection.execute('SELECT base64_password FROM passwords WHERE id = ? AND request_date = ?', [id, date]) do |row|
-            @creds[id] = {}
-            @creds[id]['password'] = row['base64_password']
-          end
+        return unless @creds[id].nil? || date != today
+
+        @creds[id] = false
+        connection.execute('SELECT base64_password FROM passwords WHERE id = ? AND request_date = ?', [id, date]) do |row|
+          @creds[id] = {}
+          @creds[id]['password'] = row['base64_password']
         end
       end
 
       def connection
-        @connection ||= SQLite3::Database.new(@filename,  { readonly: true, results_as_hash: true })
+        @connection ||= SQLite3::Database.new(@filename, { readonly: true, results_as_hash: true })
       end
 
       def today
@@ -70,4 +73,3 @@ def today
     end
   end
 end
-
diff --git a/lib/acquia-http-hmac.rb b/lib/acquia_http_hmac.rb
similarity index 95%
rename from lib/acquia-http-hmac.rb
rename to lib/acquia_http_hmac.rb
index 4b0b4ed..b8a820a 100644
--- a/lib/acquia-http-hmac.rb
+++ b/lib/acquia_http_hmac.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'addressable'
 require 'openssl'
 require 'base64'
@@ -7,8 +9,8 @@ module Acquia
   module HTTPHmac
     VERSION = '2.0'
 
+    # Class: Auth
     class Auth
-
       def initialize(realm, base64_secret)
         @realm = realm
         @secret = Base64.decode64(base64_secret)
@@ -37,7 +39,7 @@ def prepare_request_headers(args = {})
           content_type: '',
           headers: {},
           body_hash: nil,
-          version: VERSION,
+          version: VERSION
         }.merge(args)
         # Replace args so that the calling method gets all the values.
         args.replace(merged_args)
@@ -46,7 +48,7 @@ def prepare_request_headers(args = {})
 
         headers = {}
         headers['X-Authorization-Timestamp'] = args[:timestamp]
-        unless args[:body].nil? || (args[:body].length == 0)
+        unless args[:body].nil? || args[:body].empty?
           args[:body_hash] = Base64.strict_encode64(OpenSSL::Digest::SHA256.digest(args[:body]))
           headers['X-Authorization-Content-SHA256'] = args[:body_hash]
         end
@@ -81,9 +83,11 @@ def prepare_request_headers(args = {})
       def request_authenticated?(args = {})
         return false unless args[:realm] == @realm
         return false unless args[:nonce].match(/[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}/)
+
         # Allow up to 900 sec (15 min) of clock skew by default.
         allowed_skew = args[:allowed_skew] || 900
         return false if (Time.now.to_i - args[:timestamp].to_i).abs > allowed_skew
+
         base_string = prepare_base_string(args)
         signature(base_string) == args[:signature]
       end
@@ -122,9 +126,9 @@ def prepare_base_string(args = {})
         base_string_parts = [args[:http_method], args[:host].downcase, args[:path_info]]
         base_string_parts << args[:query_string]
         base_string_parts << "id=#{Addressable::URI.escape(args[:id])}&nonce=#{args[:nonce]}&realm=#{Addressable::URI.escape(@realm)}&version=#{args[:version]}"
-        headers = args[:headers].to_a.sort do |x,y|
-          (key_x, val_x) = x
-          (key_y, val_y) = y
+        headers = args[:headers].to_a.sort do |x, y|
+          (key_x,) = x
+          (key_y,) = y
           key_x.downcase <=> key_y.downcase
         end
         headers.each do |h|
@@ -146,11 +150,12 @@ def self.parse_auth_header(header)
           nonce: '',
           realm: '',
           signature: '',
-          version: '',
+          version: ''
         }
         header.to_s.sub(/^acquia-http-hmac\s+/, '').split(/,\s*/).each do |value|
-          m = value.match(/^(\w+)\=\"([^\"]*)\"$/)
+          m = value.match(/^(\w+)="([^"]*)"$/)
           break unless m
+
           attributes[m[1].to_sym] = Addressable::URI.unescape(m[2])
         end
         # Re-format custom headers to hash keys.
@@ -161,7 +166,7 @@ def self.parse_auth_header(header)
       end
 
       def signature(base_string)
-        Base64.strict_encode64(OpenSSL::HMAC.digest(OpenSSL::Digest::SHA256.new, @secret, base_string))
+        Base64.strict_encode64(OpenSSL::HMAC.digest(OpenSSL::Digest.new('SHA256'), @secret, base_string))
       end
     end
   end
diff --git a/test/acquia_spec_test.rb b/test/acquia_spec_test.rb
index 86e0324..451c847 100644
--- a/test/acquia_spec_test.rb
+++ b/test/acquia_spec_test.rb
@@ -1,8 +1,9 @@
+# frozen_string_literal: true
+
 require 'minitest/autorun'
-require_relative '../lib/acquia-http-hmac'
+require_relative '../lib/acquia_http_hmac'
 
 class TestAcquiaHmacSpec < Minitest::Test
-
   def test_fixture
     fixtures_path = File.join(File.dirname(__FILE__), '../fixtures/acquia_spec.json')
     fixtures_json = File.read(File.realpath(fixtures_path))
@@ -30,7 +31,7 @@ def test_fixture
         nonce: input['nonce'],
         timestamp: input['timestamp'],
         headers: signed_headers,
-        body_hash: body_hash,
+        body_hash: body_hash
       }
       headers = mac.prepare_request_headers(args)
 
@@ -41,18 +42,16 @@ def test_fixture
       assert(headers['Authorization'].include?("nonce=\"#{input['nonce']}\""))
       expected_headers = input['signed_headers'].join(';')
       assert(headers['Authorization'].include?("headers=\"#{expected_headers}\""))
-      assert(headers['Authorization'].include?("version=\"2.0\""))
+      assert(headers['Authorization'].include?('version="2.0"'))
       assert(headers['Authorization'].include?("signature=\"#{expectations['message_signature']}\""))
 
       # Prove that we can authenticate the request.
-      attributes = Acquia::HTTPHmac::Auth::parse_auth_header(expectations['authorization_header'])
+      attributes = Acquia::HTTPHmac::Auth.parse_auth_header(expectations['authorization_header'])
       auth_args = args.merge(attributes)
       auth_args[:allowed_skew] = input['timestamp'] + 900
       auth_args[:headers] = signed_headers
       ret = mac.request_authenticated?(auth_args)
       assert(ret, "request_authenticated? failed for #{input['name']}")
     end
-
   end
-
 end
diff --git a/test/helpers/rack_app_test_base.rb b/test/helpers/rack_app_test_base.rb
index df70ca0..06b2ac2 100644
--- a/test/helpers/rack_app_test_base.rb
+++ b/test/helpers/rack_app_test_base.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rack/test'
 
 require 'acquia-http-hmac/rack_authenticate'
@@ -17,7 +19,7 @@ def prepare_get(id, password, args = {})
       http_method: 'GET',
       host: 'example.org', # Default in the Rack test
       id: id,
-      path_info: '/hello',
+      path_info: '/hello'
     }.merge(args)
     mac.prepare_request_headers(args).each do |name, value|
       header(name, value)
@@ -34,7 +36,7 @@ def prepare_post(id, password, body, args = {})
       id: id,
       path_info: '/hello',
       body: body,
-      content_type: 'application/json',
+      content_type: 'application/json'
     }.merge(args)
     mac.prepare_request_headers(args).each do |name, value|
       header(name, value)
@@ -46,20 +48,20 @@ def prepare_post(id, password, body, args = {})
   # Add just the auth middleware
   def app
     passwords = get_password_storage
-    Rack::Builder.new {
-      map "/" do
+    Rack::Builder.new do
+      map '/' do
         # Need this base middleware so that request.logger is defined.
         use Rack::NullLogger
         options = {
           password_storage: passwords,
           realm: 'Test',
           nonce_checker: Acquia::HTTPHmac::MemoryNonceChecker.new,
-          excluded_paths: ['/healthcheck'],
+          excluded_paths: ['/healthcheck']
         }
         use Acquia::HTTPHmac::RackAuthenticate, options
         run Example::App
       end
-    }.to_app
+    end.to_app
   end
 
   def test_401_get
@@ -86,7 +88,7 @@ def test_403_bad_password_get
     passwords = get_password_storage
     id = passwords.ids.first
     # Use an invalid password by adding a letter.
-    prepare_get(id, 'a' + get_password(id))
+    prepare_get(id, "a#{get_password(id)}")
     get '/hello'
     assert_equal(403, last_response.status)
   end
@@ -95,7 +97,7 @@ def test_403_bad_id_get
     passwords = get_password_storage
     id = passwords.ids.first
     # Use an invalid id by adding a letter.
-    prepare_get(id + 'a', get_password(id))
+    prepare_get("#{id}a", get_password(id))
     get '/hello'
     assert_equal(403, last_response.status)
   end
@@ -126,7 +128,7 @@ def test_403_missing_header_get
     passwords = get_password_storage
     id = passwords.ids.first
     # Pass a header expected to be signed.
-    prepare_get(id, get_password(id), headers: {'X-Custom-Foo' => 'nick'})
+    prepare_get(id, get_password(id), headers: { 'X-Custom-Foo' => 'nick' })
     get '/hello'
     # The expected header was missing.
     assert_equal(403, last_response.status)
@@ -136,7 +138,7 @@ def test_403_mismatched_header_get
     passwords = get_password_storage
     id = passwords.ids.first
     # Pass a header expected to be signed.
-    prepare_get(id, get_password(id), headers: {'X-Custom-Foo' => 'nick'})
+    prepare_get(id, get_password(id), headers: { 'X-Custom-Foo' => 'nick' })
     # The expected header has a different value.
     header('X-Custom-Foo', 'nack')
     get '/hello'
@@ -171,7 +173,7 @@ def test_get_with_extra_header
     passwords = get_password_storage
     id = passwords.ids.first
     # Pass a header expected to be signed.
-    prepare_get(id, get_password(id), headers: {'X-Custom-Foo' => 'nick'})
+    prepare_get(id, get_password(id), headers: { 'X-Custom-Foo' => 'nick' })
     header('X-Custom-Foo', 'nick')
     get '/hello'
     assert_equal(200, last_response.status)
@@ -181,7 +183,7 @@ def test_get_with_quoted_header
     passwords = get_password_storage
     id = passwords.ids.first
     # Pass a header expected to be signed.
-    prepare_get(id, get_password(id), headers: {'X-Custom-Foo' => '"nick"'})
+    prepare_get(id, get_password(id), headers: { 'X-Custom-Foo' => '"nick"' })
     header('X-Custom-Foo', '"nick"')
     get '/hello'
     assert_equal(200, last_response.status)
@@ -191,7 +193,7 @@ def test_get_with_spaces_in_header
     passwords = get_password_storage
     id = passwords.ids.first
     # Pass a header expected to be signed.
-    prepare_get(id, get_password(id), headers: {'X-Custom-Foo' => 'a b c '})
+    prepare_get(id, get_password(id), headers: { 'X-Custom-Foo' => 'a b c ' })
     header('X-Custom-Foo', ' a b c   ')
     get '/hello'
     assert_equal(200, last_response.status)
@@ -201,7 +203,7 @@ def test_get_with_spaces_in_quoted_header
     passwords = get_password_storage
     id = passwords.ids.first
     # Pass a header expected to be signed.
-    prepare_get(id, get_password(id), headers: {'X-Custom-Foo' => '"hi nick" '})
+    prepare_get(id, get_password(id), headers: { 'X-Custom-Foo' => '"hi nick" ' })
     header('X-Custom-Foo', ' "hi nick"   ')
     get '/hello'
     assert_equal(200, last_response.status)
@@ -223,7 +225,7 @@ def test_403_bad_body_post
     body = '{"hello":"hi.bob","params":["5","4","8"]}'
     prepare_post(id, get_password(id), body)
     # Create a mismatch by adding an extra character to the body.
-    post '/hello', body + 'a'
+    post '/hello', "#{body}a"
     assert_equal(403, last_response.status)
   end
 end
diff --git a/test/httphmac_test.rb b/test/httphmac_test.rb
index 30f25d5..0a409d4 100644
--- a/test/httphmac_test.rb
+++ b/test/httphmac_test.rb
@@ -1,39 +1,40 @@
+# frozen_string_literal: true
+
 require 'minitest/autorun'
-require_relative '../lib/acquia-http-hmac'
+require_relative '../lib/acquia_http_hmac'
 
 class TestHTTPHmac < Minitest::Test
-
   def test_prepare_request_get
-    mac = Acquia::HTTPHmac::Auth.new('TestRealm', "dGhlc2VjcmV0")
+    mac = Acquia::HTTPHmac::Auth.new('TestRealm', 'dGhlc2VjcmV0')
     args = {
       http_method: 'GET',
       host: 'www.example.com',
       id: 'test',
-      path_info: '/hello',
+      path_info: '/hello'
     }
     headers = mac.prepare_request_headers(args)
     auth_header = headers['Authorization']
-    assert(auth_header.match /acquia-http-hmac realm="TestRealm",id="test",nonce="[0-9a-f-]{36}",version="2\.0",headers="[^"]*",signature="[^"]+"/)
+    assert(auth_header.match(/acquia-http-hmac realm="TestRealm",id="test",nonce="[0-9a-f-]{36}",version="2\.0",headers="[^"]*",signature="[^"]+"/))
 
     # Repeat with known nonce and timestamp
     # "dGhlc2VjcmV0" is base64 of 'thesecret'
-    mac = Acquia::HTTPHmac::Auth.new('TestRealm', "dGhlc2VjcmV0")
-    args[:nonce] = "f2c91a46-b505-4b50-afa2-21364dc8ff34"
-    args[:timestamp] = "1432180014"
+    mac = Acquia::HTTPHmac::Auth.new('TestRealm', 'dGhlc2VjcmV0')
+    args[:nonce] = 'f2c91a46-b505-4b50-afa2-21364dc8ff34'
+    args[:timestamp] = '1432180014'
     headers = mac.prepare_request_headers(args)
     auth_header = headers['Authorization']
     # We expect the following base string:
     # GET
     # www.example.com
     # /hello
-    # 
+    #
     # id=test&nonce=f2c91a46-b505-4b50-afa2-21364dc8ff34&realm=TestRealm&version=2.0
     # 1432180014
 
     m = auth_header.match(/.*,signature="([^"]+)"$/)
     assert(m, 'Did not find signature')
     # Compare to a signature calulated with the base string in PHP.
-    assert_equal("hKHBXbx9KDirAWpvYKGOqHVSLn6yjD3V5aaQTRklPPA=", m[1])
+    assert_equal('hKHBXbx9KDirAWpvYKGOqHVSLn6yjD3V5aaQTRklPPA=', m[1])
     # Repeast with a query string that needs to be normalized.
     args[:query_string] = 'base=foo&all'
     headers = mac.prepare_request_headers(args)
@@ -48,24 +49,24 @@ def test_prepare_request_get
     m = auth_header.match(/.*,signature="([^"]+)"$/)
     assert(m, 'Did not find signature')
     # Compare to a signature calulated with the base string in PHP.
-    assert_equal("dvl8wLvEcLbAtKfvIYaIGThIXHBpOtOTw7dQX4nBjwM=", m[1])
+    assert_equal('dvl8wLvEcLbAtKfvIYaIGThIXHBpOtOTw7dQX4nBjwM=', m[1])
   end
 
   def test_prepare_request_get_headers
-    mac = Acquia::HTTPHmac::Auth.new('TestRealm', "dGhlc2VjcmV0")
+    mac = Acquia::HTTPHmac::Auth.new('TestRealm', 'dGhlc2VjcmV0')
     args = {
       http_method: 'GET',
       host: 'www.example.com',
       id: 'test',
       path_info: '/hello',
       query_string: 'base=foo&all',
-      nonce: "f2c91a46-b505-4b50-afa2-21364dc8ff34",
-      timestamp: "1432180014",
-      headers: {'x-custom-foo' => 'nick'}
+      nonce: 'f2c91a46-b505-4b50-afa2-21364dc8ff34',
+      timestamp: '1432180014',
+      headers: { 'x-custom-foo' => 'nick' }
     }
     headers = mac.prepare_request_headers(args)
     auth_header = headers['Authorization']
-    assert(auth_header.match /acquia-http-hmac realm="TestRealm",id="test",nonce="[0-9a-f-]{36}",version="2\.0",headers="[^"]*",signature="[^"]+"/)
+    assert(auth_header.match(/acquia-http-hmac realm="TestRealm",id="test",nonce="[0-9a-f-]{36}",version="2\.0",headers="[^"]*",signature="[^"]+"/))
 
     # We expect the following base string:
     # GET
@@ -78,37 +79,36 @@ def test_prepare_request_get_headers
     m = auth_header.match(/.*,signature="([^"]+)"$/)
     assert(m, 'Did not find signature')
     # Compare to a signature calulated with the base string in PHP.
-    assert_equal("RuYnAieiiOOWWAZ0tjZ/+HMebpBCBhGSYEWWBF+lP28=", m[1])
+    assert_equal('RuYnAieiiOOWWAZ0tjZ/+HMebpBCBhGSYEWWBF+lP28=', m[1])
   end
 
   def test_prepare_request_post
     # Use known nonce and timestamp
-    mac = Acquia::HTTPHmac::Auth.new('TestRealm', "dGhlc2VjcmV0")
+    mac = Acquia::HTTPHmac::Auth.new('TestRealm', 'dGhlc2VjcmV0')
     args = {
       http_method: 'POST',
       host: 'www.example.com',
       id: 'test',
       path_info: '/hello',
-      nonce: "f2c91a46-b505-4b50-afa2-21364dc8ab34",
-      timestamp: "1432180014",
+      nonce: 'f2c91a46-b505-4b50-afa2-21364dc8ab34',
+      timestamp: '1432180014'
     }
     args[:body] = '{"method":"hi.bob","params":["5","4","8"]}'
     args[:content_type] = 'application/json'
     headers = mac.prepare_request_headers(args)
     auth_header = headers['Authorization']
-    assert(auth_header.match /acquia-http-hmac realm="TestRealm",id="test",nonce="[0-9a-f-]{36}",version="2\.0",headers="[^"]*",signature="[^"]+"/)
-    assert_equal(headers['X-Authorization-Content-SHA256'], "6paRNxUA7WawFxJpRp4cEixDjHq3jfIKX072k9slalo=")
+    assert(auth_header.match(/acquia-http-hmac realm="TestRealm",id="test",nonce="[0-9a-f-]{36}",version="2\.0",headers="[^"]*",signature="[^"]+"/))
+    assert_equal(headers['X-Authorization-Content-SHA256'], '6paRNxUA7WawFxJpRp4cEixDjHq3jfIKX072k9slalo=')
     # We expect the following base string:
     # POST
     # www.example.com
     # /hello
-    # 
+    #
     # id=test&nonce=f2c91a46-b505-4b50-afa2-21364dc8ab34&realm=TestRealm&version=2.0
     # 1432180014
     # application/json
     # 6paRNxUA7WawFxJpRp4cEixDjHq3jfIKX072k9slalo=
     m = auth_header.match(/.*,signature="([^"]+)"$/)
-    assert_equal("Un7AVsJ80yxzR0Jn+LB6orziDrAistPNm3h33bNZiJ0=", m[1])
+    assert_equal('Un7AVsJ80yxzR0Jn+LB6orziDrAistPNm3h33bNZiJ0=', m[1])
   end
-
 end
diff --git a/test/httphmac_verify_test.rb b/test/httphmac_verify_test.rb
index bf2a5dc..9071d84 100644
--- a/test/httphmac_verify_test.rb
+++ b/test/httphmac_verify_test.rb
@@ -1,86 +1,87 @@
+# frozen_string_literal: true
+
 require 'minitest/autorun'
 require 'base64'
-require_relative '../lib/acquia-http-hmac'
+require_relative '../lib/acquia_http_hmac'
 
 class HmacVerifyTest < Minitest::Test
-
-  def get_params
+  def params
     {
-      :http_method => 'GET',
-      :host => 'example.com',
-      :id => '12345',
-      :path_info => "/some/path",
-      :query_string => "foo=bar",
-      :body => nil,
-      :content_type => "application/json",
-      :nonce => '869a8b00-f96f-4a9e-98e6-a6e38b0de316',
-      :timestamp => Time.now.to_i
+      http_method: 'GET',
+      host: 'example.com',
+      id: '12345',
+      path_info: '/some/path',
+      query_string: 'foo=bar',
+      body: nil,
+      content_type: 'application/json',
+      nonce: '869a8b00-f96f-4a9e-98e6-a6e38b0de316',
+      timestamp: Time.now.to_i
     }
   end
 
   def post_params
     {
-      :http_method => 'POST',
-      :host => 'example.com',
-      :id => '54321',
-      :path_info => "/another/path",
-      :query_string => "foo=bar",
-      :body => 'tbd: yes',
-      :content_type => "application/json",
-      :nonce => '869a8b00-f96f-4a9e-98e6-a6e38b0de316',
-      :timestamp => Time.now.to_i
+      http_method: 'POST',
+      host: 'example.com',
+      id: '54321',
+      path_info: '/another/path',
+      query_string: 'foo=bar',
+      body: 'tbd: yes',
+      content_type: 'application/json',
+      nonce: '869a8b00-f96f-4a9e-98e6-a6e38b0de316',
+      timestamp: Time.now.to_i
     }
   end
 
   def setup
     # "dGhlc2VjcmV0" is base64 of 'thesecret'
-    @secret = "dGhlc2VjcmV0"
+    @secret = 'dGhlc2VjcmV0'
     @realm = 'TestRealm'
     hmac = Acquia::HTTPHmac::Auth.new(@realm, @secret)
 
-    @req_get = hmac.prepare_request_headers(get_params)
+    @req_get = hmac.prepare_request_headers(params)
     @req_post = hmac.prepare_request_headers(post_params)
   end
 
   def test_get_no_body
-    attributes = Acquia::HTTPHmac::Auth::parse_auth_header(@req_get['Authorization'])
+    attributes = Acquia::HTTPHmac::Auth.parse_auth_header(@req_get['Authorization'])
     hmac = Acquia::HTTPHmac::Auth.new(@realm, @secret)
-    ret = hmac.request_authenticated?(get_params.merge(attributes))
-    assert(ret, "request_authenticated? failed for GET")
+    ret = hmac.request_authenticated?(params.merge(attributes))
+    assert(ret, 'request_authenticated? failed for GET')
   end
 
   def test_it_fails_with_invalid_realm
-    attributes = Acquia::HTTPHmac::Auth::parse_auth_header(@req_get['Authorization'])
+    attributes = Acquia::HTTPHmac::Auth.parse_auth_header(@req_get['Authorization'])
     hmac = Acquia::HTTPHmac::Auth.new('bad_realm', @secret)
-    ret = hmac.request_authenticated?(get_params.merge(attributes))
-    assert(!ret, "request_authenticated? accepted invalid realm")
+    ret = hmac.request_authenticated?(params.merge(attributes))
+    assert(!ret, 'request_authenticated? accepted invalid realm')
   end
 
   def test_it_fails_with_invalid_secret
-    attributes = Acquia::HTTPHmac::Auth::parse_auth_header(@req_get['Authorization'])
+    attributes = Acquia::HTTPHmac::Auth.parse_auth_header(@req_get['Authorization'])
     hmac = Acquia::HTTPHmac::Auth.new(@realm, Base64.strict_encode64('wrong password'))
-    ret = hmac.request_authenticated?(get_params.merge(attributes))
-    assert(!ret, "request_authenticated? accepted invalid secret")
+    ret = hmac.request_authenticated?(params.merge(attributes))
+    assert(!ret, 'request_authenticated? accepted invalid secret')
   end
 
   def test_post_with_body
     params = post_params
     params[:body_hash] = @req_post['X-Authorization-Content-SHA256']
-    attributes = Acquia::HTTPHmac::Auth::parse_auth_header(@req_post['Authorization'])
+    attributes = Acquia::HTTPHmac::Auth.parse_auth_header(@req_post['Authorization'])
     hmac = Acquia::HTTPHmac::Auth.new(@realm, @secret)
     ret = hmac.request_authenticated?(params.merge(attributes))
-    assert(ret, "request_authenticated? failed for POST")
+    assert(ret, 'request_authenticated? failed for POST')
   end
 
   def test_it_requires_recent_timestamp
     # We need to do our own GET with a wrong timestamp here:
-    params = get_params
+    parameters = params
     # Put it 901 seconds in the past.
-    params[:timestamp] = params[:timestamp].to_i - 901
+    parameters[:timestamp] = parameters[:timestamp].to_i - 901
     hmac = Acquia::HTTPHmac::Auth.new(@realm, @secret)
-    get = hmac.prepare_request_headers(params)
-    attributes = Acquia::HTTPHmac::Auth::parse_auth_header(get['Authorization'])
-    ret = hmac.request_authenticated?(params.merge(attributes))
-    assert(!ret, "request_authenticated? accepted old timestamp")
+    get = hmac.prepare_request_headers(parameters)
+    attributes = Acquia::HTTPHmac::Auth.parse_auth_header(get['Authorization'])
+    ret = hmac.request_authenticated?(parameters.merge(attributes))
+    assert(!ret, 'request_authenticated? accepted old timestamp')
   end
-end
\ No newline at end of file
+end
diff --git a/test/rack_simple_app_test.rb b/test/rack_simple_app_test.rb
index 55590d6..9b8fdb8 100644
--- a/test/rack_simple_app_test.rb
+++ b/test/rack_simple_app_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'minitest/autorun'
 require_relative 'helpers/rack_app_test_base'
 
@@ -5,10 +7,10 @@ class TestRackApp < Minitest::Test
   include TestRackAppBase
 
   def get_password_storage
-    @passwords ||= Acquia::HTTPHmac::FilePasswordStorage.new(File.dirname(__FILE__) + '/../fixtures/passwords.yml')
+    @get_password_storage ||= Acquia::HTTPHmac::FilePasswordStorage.new("#{File.dirname(__FILE__)}/../fixtures/passwords.yml")
   end
 
-  def get_password(id, timestamp = nil)
+  def get_password(id, _timestamp = nil)
     get_password_storage.data(id)['password']
   end
 end
diff --git a/test/rack_sqlite3_app_test.rb b/test/rack_sqlite3_app_test.rb
index d223333..fcf8993 100644
--- a/test/rack_sqlite3_app_test.rb
+++ b/test/rack_sqlite3_app_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'minitest/autorun'
 require 'base64'
 require 'openssl'
@@ -10,28 +12,27 @@ class TestSqlite3RackApp < Minitest::Test
 
   def setup
     @dbfile = File.join(File.dirname(__FILE__), '/../fixtures/passwords.sqlite3')
-    @passwords_file = File.dirname(__FILE__) + '/../fixtures/passwords.yml'
+    @passwords_file = "#{File.dirname(__FILE__)}/../fixtures/passwords.yml"
     s = ExampleSQLite3Setup.new(@dbfile, @passwords_file)
     s.write_database
     @binary_passwords = {}
-    YAML.safe_load(File.read(@passwords_file)).each do |id,data|
+    YAML.safe_load(File.read(@passwords_file)).each do |id, data|
       @binary_passwords[id] = Base64.decode64(data['password'])
     end
   end
 
-  def get_password(id, timestamp = nil)
+  def get_password(id, _timestamp = nil)
     ts = Time.now.to_i
     date = Time.at(ts).utc.strftime('%F')
     realm = 'Test'
     # Run a 2-step HMAC KDF using date and realm
-    sha256 = OpenSSL::Digest::SHA256.new
+    sha256 = OpenSSL::Digest.new('SHA256')
     derived_pass1 = OpenSSL::HMAC.digest(sha256, @binary_passwords[id], date)
     derived_pass2 = OpenSSL::HMAC.digest(sha256, derived_pass1, realm)
     Base64.strict_encode64(derived_pass2)
   end
 
   def get_password_storage
-    @storage ||= Acquia::HTTPHmac::SQLite3PasswordStorage.new(@dbfile)
+    @get_password_storage ||= Acquia::HTTPHmac::SQLite3PasswordStorage.new(@dbfile)
   end
-
 end