Token object for verifying and signing tokens

.gitignore

@@ -12,3 +12,4 @@ coverage/
 .byebug_history
 *.gem
 doc/
+.yardoc/

CHANGELOG.md

@@ -28,6 +28,7 @@ Notable changes in the upcoming **version 3.0**:
 
 **Features:**
 
+- JWT::Token and JWT::EncodedToken for signing and verifying tokens [#621](https://github.com/jwt/ruby-jwt/pull/621) ([@anakinj](https://github.com/anakinj))
 - Your contribution here
 
 **Fixes and enhancements:**

README.md

@@ -221,6 +221,30 @@ decoded_token = JWT.decode token, rsa_public, true, { algorithm: 'PS256' }
 puts decoded_token
 ```
 
+### Using a Token object
+
+The `JWT::Token` and `JWT::EncodedToken` classes can be used to manage your JWTs.
+
+```ruby
+token = JWT::Token.new(payload: { exp: Time.now.to_i + 60, jti: '1234', sub: "my-subject" }, header: { kid: 'hmac' })
+token.sign!(algorithm: 'HS256', key: "secret")
+
+token.jwt # => "eyJhbGciOiJIUzI1N..."
+```
+
+The `JWT::EncodedToken` can be used to create a token object that allows verification of signatures and claims
+```ruby
+encoded_token = JWT::EncodedToken.new(token.jwt)
+
+encoded_token.verify_signature!(algorithm: 'HS256', key: "secret")
+encoded_token.verify_signature!(algorithm: 'HS256', key: "wrong_secret") # raises JWT::VerificationError
+encoded_token.verify_claims!(:exp, :jti)
+encoded_token.verify_claims!(sub: ["not-my-subject"]) # raises JWT::InvalidSubError
+encoded_token.claim_errors(sub: ["not-my-subject"]).map(&:message) # => ["Invalid subject. Expected [\"not-my-subject\"], received my-subject"]
+encoded_token.payload # => { 'exp'=>1234, 'jti'=>'1234", 'sub'=>'my-subject' }
+encoded_token.header # {'kid'=>'hmac', 'alg'=>'HS256'}
+```
+
 ### **Custom algorithms**
 
 When encoding or decoding a token, you can pass in a custom object through the `algorithm` option to handle signing or verification. This custom object must include or extend the `JWT::JWA::SigningAlgorithm` module and implement certain methods:
@@ -626,7 +650,6 @@ algorithms = jwks.map { |key| key[:alg] }.compact.uniq
 JWT.decode(token, nil, true, algorithms: algorithms, jwks: jwks)
 ```
 
-
 The `jwks` option can also be given as a lambda that evaluates every time a kid is resolved.
 This can be used to implement caching of remotely fetched JWK Sets.
 

lib/jwt.rb

@@ -10,6 +10,8 @@
 require 'jwt/error'
 require 'jwt/jwk'
 require 'jwt/claims'
+require 'jwt/encoded_token'
+require 'jwt/token'
 
 require 'jwt/claims_validator'
 require 'jwt/verify'

lib/jwt/claims.rb

@@ -11,6 +11,7 @@
 require_relative 'claims/subject'
 require_relative 'claims/decode_verifier'
 require_relative 'claims/verifier'
+require_relative 'claims/verification_methods'
 
 module JWT
   # JWT Claim verifications
@@ -48,7 +49,7 @@ def verify!(payload, options)
       # @return [void]
       # @raise [JWT::DecodeError] if any claim is invalid.
       def verify_payload!(payload, *options)
-        verify_token!(VerificationContext.new(payload: payload), *options)
+        Verifier.verify!(VerificationContext.new(payload: payload), *options)
       end
 
       # Checks if the claims in the JWT payload are valid.
@@ -65,17 +66,7 @@ def valid_payload?(payload, *options)
       # @param options [Array] the options for verifying the claims.
       # @return [Array<JWT::Claims::Error>] the errors in the claims of the JWT
       def payload_errors(payload, *options)
-        token_errors(VerificationContext.new(payload: payload), *options)
-      end
-
-      private
-
-      def verify_token!(token, *options)
-        Verifier.verify!(token, *options)
-      end
-
-      def token_errors(token, *options)
-        Verifier.errors(token, *options)
+        Verifier.errors(VerificationContext.new(payload: payload), *options)
       end
     end
   end

lib/jwt/claims/decode_verifier.rb

@@ -4,12 +4,12 @@ module JWT
   module Claims
     # Context class to contain the data passed to individual claim validators
     #
-    # @private
+    # @api private
     VerificationContext = Struct.new(:payload, keyword_init: true)
 
     # Verifiers to support the ::JWT.decode method
     #
-    # @private
+    # @api private
     module DecodeVerifier
       VERIFIERS = {
         verify_expiration: ->(options) { Claims::Expiration.new(leeway: options[:exp_leeway] || options[:leeway]) },
@@ -25,7 +25,7 @@ module DecodeVerifier
       private_constant(:VERIFIERS)
 
       class << self
-        # @private
+        # @api private
         def verify!(payload, options)
           VERIFIERS.each do |key, verifier_builder|
             next unless options[key] || options[key.to_s]

lib/jwt/claims/verification_methods.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module JWT
+  module Claims
+    # @api private
+    module VerificationMethods
+      def verify_claims!(*options)
+        Verifier.verify!(self, *options)
+      end
+
+      def claim_errors(*options)
+        Verifier.errors(self, *options)
+      end
+
+      def valid_claims?(*options)
+        claim_errors(*options).empty?
+      end
+    end
+  end
+end

lib/jwt/claims/verifier.rb

@@ -2,7 +2,7 @@
 
 module JWT
   module Claims
-    # @private
+    # @api private
     module Verifier
       VERIFIERS = {
         exp: ->(options) { Claims::Expiration.new(leeway: options.dig(:exp, :leeway)) },
@@ -20,15 +20,15 @@ module Verifier
       private_constant(:VERIFIERS)
 
       class << self
-        # @private
+        # @api private
         def verify!(context, *options)
           iterate_verifiers(*options) do |verifier, verifier_options|
             verify_one!(context, verifier, verifier_options)
           end
           nil
         end
 
-        # @private
+        # @api private
         def errors(context, *options)
           errors = []
           iterate_verifiers(*options) do |verifier, verifier_options|
@@ -39,7 +39,8 @@ def errors(context, *options)
           errors
         end
 
-        # @private
+        private
+
         def iterate_verifiers(*options)
           options.each do |element|
             if element.is_a?(Hash)
@@ -50,8 +51,6 @@ def iterate_verifiers(*options)
           end
         end
 
-        private
-
         def verify_one!(context, verifier, options)
           verifier_builder = VERIFIERS.fetch(verifier) { raise ArgumentError, "#{verifier} not a valid claim verifier" }
           verifier_builder.call(options || {}).verify!(context: context)

lib/jwt/decode.rb

@@ -10,62 +10,50 @@ class Decode
     def initialize(jwt, key, verify, options, &keyfinder)
       raise JWT::DecodeError, 'Nil JSON web token' unless jwt
 
-      @jwt = jwt
+      @token = EncodedToken.new(jwt)
       @key = key
       @options = options
-      @segments = jwt.split('.')
       @verify = verify
-      @signature = ''
       @keyfinder = keyfinder
     end
 
     def decode_segments
       validate_segment_count!
       if @verify
-        decode_signature
         verify_algo
         set_key
         verify_signature
-        verify_claims
+        Claims::DecodeVerifier.verify!(token.payload, @options)
       end
-      raise JWT::DecodeError, 'Not enough or too many segments' unless header && payload
 
-      [payload, header]
+      [token.payload, token.header]
     end
 
     private
 
-    def verify_signature
-      return unless @key || @verify
+    attr_reader :token
 
+    def verify_signature
       return if none_algorithm?
 
       raise JWT::DecodeError, 'No verification key available' unless @key
 
-      return if Array(@key).any? { |key| verify_signature_for?(key) }
-
-      raise JWT::VerificationError, 'Signature verification failed'
+      token.verify_signature!(algorithm: allowed_and_valid_algorithms, key: @key)
     end
 
     def verify_algo
       raise JWT::IncorrectAlgorithm, 'An algorithm must be specified' if allowed_algorithms.empty?
-      raise JWT::DecodeError, 'Token header not a JSON object' unless header.is_a?(Hash)
+      raise JWT::DecodeError, 'Token header not a JSON object' unless token.header.is_a?(Hash)
       raise JWT::IncorrectAlgorithm, 'Token is missing alg header' unless alg_in_header
       raise JWT::IncorrectAlgorithm, 'Expected a different algorithm' if allowed_and_valid_algorithms.empty?
     end
 
     def set_key
       @key = find_key(&@keyfinder) if @keyfinder
-      @key = ::JWT::JWK::KeyFinder.new(jwks: @options[:jwks], allow_nil_kid: @options[:allow_nil_kid]).key_for(header['kid']) if @options[:jwks]
+      @key = ::JWT::JWK::KeyFinder.new(jwks: @options[:jwks], allow_nil_kid: @options[:allow_nil_kid]).key_for(token.header['kid']) if @options[:jwks]
       return unless (x5c_options = @options[:x5c])
 
-      @key = X5cKeyFinder.new(x5c_options[:root_certificates], x5c_options[:crls]).from(header['x5c'])
-    end
-
-    def verify_signature_for?(key)
-      allowed_and_valid_algorithms.any? do |alg|
-        alg.verify(data: signing_input, signature: @signature, verification_key: key)
-      end
+      @key = X5cKeyFinder.new(x5c_options[:root_certificates], x5c_options[:crls]).from(token.header['x5c'])
     end
 
     def allowed_and_valid_algorithms
@@ -91,70 +79,32 @@ def allowed_algorithms
     end
 
     def resolve_allowed_algorithms
-      algs = given_algorithms.map { |alg| JWA.resolve(alg) }
-
-      sort_by_alg_header(algs)
-    end
-
-    # Move algorithms matching the JWT alg header to the beginning of the list
-    def sort_by_alg_header(algs)
-      return algs if algs.size <= 1
-
-      algs.partition { |alg| alg.valid_alg?(alg_in_header) }.flatten
+      given_algorithms.map { |alg| JWA.resolve(alg) }
     end
 
     def find_key(&keyfinder)
-      key = (keyfinder.arity == 2 ? yield(header, payload) : yield(header))
+      key = (keyfinder.arity == 2 ? yield(token.header, token.payload) : yield(token.header))
       # key can be of type [string, nil, OpenSSL::PKey, Array]
       return key if key && !Array(key).empty?
 
       raise JWT::DecodeError, 'No verification key available'
     end
 
-    def verify_claims
-      Claims::DecodeVerifier.verify!(payload, @options)
-    end
-
     def validate_segment_count!
-      return if segment_length == 3
-      return if !@verify && segment_length == 2 # If no verifying required, the signature is not needed
-      return if segment_length == 2 && none_algorithm?
+      segment_count = token.jwt.count('.') + 1
+      return if segment_count == 3
+      return if !@verify && segment_count == 2 # If no verifying required, the signature is not needed
+      return if segment_count == 2 && none_algorithm?
 
       raise JWT::DecodeError, 'Not enough or too many segments'
     end
 
-    def segment_length
-      @segments.count
-    end
-
     def none_algorithm?
       alg_in_header == 'none'
     end
 
-    def decode_signature
-      @signature = ::JWT::Base64.url_decode(@segments[2] || '')
-    end
-
     def alg_in_header
-      header['alg']
-    end
-
-    def header
-      @header ||= parse_and_decode @segments[0]
-    end
-
-    def payload
-      @payload ||= parse_and_decode @segments[1]
-    end
-
-    def signing_input
-      @segments.first(2).join('.')
-    end
-
-    def parse_and_decode(segment)
-      JWT::JSON.parse(::JWT::Base64.url_decode(segment))
-    rescue ::JSON::ParserError
-      raise JWT::DecodeError, 'Invalid segment encoding'
+      token.header['alg']
     end
   end
 end