Drop support for HS512256

Author: anakinj

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 - JWT::EncodedToken#verify! method that bundles signature and claim validation [#647](https://github.com/jwt/ruby-jwt/pull/647) ([@anakinj](https://github.com/anakinj))
 - Require token signature to be verified before accessing payload (Breaking change!) [#648](https://github.com/jwt/ruby-jwt/pull/648) ([@anakinj](https://github.com/anakinj))
+- Drop support for the HS512256 algorithm (Breaking change!) [#650](https://github.com/jwt/ruby-jwt/pull/650) ([@anakinj](https://github.com/anakinj))
 - Your contribution here
 
 **Fixes and enhancements:**

lib/jwt/jwa.rb

@@ -20,12 +20,6 @@
 
 require_relative 'jwa/eddsa' if JWT.rbnacl?
 
-if JWT.rbnacl_6_or_greater?
-  require_relative 'jwa/hmac_rbnacl'
-elsif JWT.rbnacl?
-  require_relative 'jwa/hmac_rbnacl_fixed'
-end
-
 module JWT
   # The JWA module contains all supported algorithms.
   module JWA

lib/jwt/jwa/hmac_rbnacl.rb

@@ -25,7 +25,6 @@
       'ES256K_public' => test_pkey('ec256k-public.pem'),
       'NONE' => 'eyJhbGciOiJub25lIn0.eyJ1c2VyX2lkIjoic29tZUB1c2VyLnRsZCJ9.',
       'HS256' => 'eyJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoic29tZUB1c2VyLnRsZCJ9.kWOVtIOpWcG7JnyJG0qOkTDbOy636XrrQhMm_8JrRQ8',
-      'HS512256' => 'eyJhbGciOiJIUzUxMjI1NiJ9.eyJ1c2VyX2lkIjoic29tZUB1c2VyLnRsZCJ9.Ds_4ibvf7z4QOBoKntEjDfthy3WJ-3rKMspTEcHE2bA',
       'HS384' => 'eyJhbGciOiJIUzM4NCJ9.eyJ1c2VyX2lkIjoic29tZUB1c2VyLnRsZCJ9.VuV4j4A1HKhWxCNzEcwc9qVF3frrEu-BRLzvYPkbWO0LENRGy5dOiBQ34remM3XH',
       'HS512' => 'eyJhbGciOiJIUzUxMiJ9.eyJ1c2VyX2lkIjoic29tZUB1c2VyLnRsZCJ9.8zNtCBTJIZTHpZ-BkhR-6sZY1K85Nm5YCKqV3AxRdsBJDt_RR-REH2db4T3Y0uQwNknhrCnZGvhNHrvhDwV1kA',
       'RS256' => 'eyJhbGciOiJSUzI1NiJ9.eyJ1c2VyX2lkIjoic29tZUB1c2VyLnRsZCJ9.eSXvWP4GViiwUALj_-qTxU68I1oM0XjgDsCZBBUri2Ghh9d75QkVDoZ_v872GaqunN5A5xcnBK0-cOq-CR6OwibgJWfOt69GNzw5RrOfQ2mz3QI3NYEq080nF69h8BeqkiaXhI24Q51joEgfa9aj5Y-oitLAmtDPYTm7vTcdGufd6AwD3_3jajKBwkh0LPSeMtbe_5EyS94nFoEF9OQuhJYjUmp7agsBVa8FFEjVw5jEgVqkvERSj5hSY4nEiCAomdVxIKBfykyi0d12cgjhI7mBFwWkPku8XIPGZ7N8vpiSLdM68BnUqIK5qR7NAhtvT7iyLFgOqhZNUQ6Ret5VpQ',
@@ -106,10 +105,7 @@
     end
   end
 
-  algorithms = %w[HS256 HS384 HS512]
-  algorithms << 'HS512256' if JWT.rbnacl?
-
-  algorithms.each do |alg|
+  %w[HS256 HS384 HS512].each do |alg|
     context "alg: #{alg}" do
       it 'should generate a valid token' do
         token = JWT.encode payload, data[:secret], alg