Make subscription tokens compatible with Centrifugo v4+ (centrifugal#24)

Author: trushkevich

README.md

@@ -71,7 +71,7 @@ All channels starting with $ considered private and require a **channel token**
 Private channel subscription token is also JWT([see the claims](https://centrifugal.github.io/centrifugo/server/private_channels/))
 
 ```ruby
-notary.issue_channel_token(client: 'client', channel: 'channel', exp: 1629050099, info: { scope: 'admin' }) 
+notary.issue_channel_token(sub: '42', channel: 'channel', exp: 1629050099, info: { scope: 'admin' }) 
 
 #=> "eyJhbGciOiJIUzI1NiJ9..."
 ```

lib/cent/notary.rb

@@ -57,8 +57,8 @@ def issue_connection_token(sub:, info: nil, exp: nil)
 
     # Generate JWT for private channels
     #
-    # @param client [String]
-    #   Client ID which wants to subscribe on channel
+    # @param sub [String]
+    #   Standard JWT claim which must contain an ID of current application user.
     #
     # @option channel [String]
     #   Channel that client tries to subscribe to (string).
@@ -71,16 +71,16 @@ def issue_connection_token(sub:, info: nil, exp: nil)
     #   client connection that can be provided for Centrifugo.
     #
     # @example Get private channel JWT with expiration and extra info
-    #   notary.issue_channel_token(client: 'client', channel: 'channel', exp: 3600, info: { 'message' => 'wat' })
+    #   notary.issue_channel_token(sub: '1', channel: 'channel', exp: 3600, info: { 'message' => 'wat' })
     #     #=> eyJhbGciOiJIUzI1NiJ9.eyJjbGllbnQiOiJjbG..."
     #
     # @see (https://centrifugal.github.io/centrifugo/server/private_channels/)
     #
     # @return [String]
     #
-    def issue_channel_token(client:, channel:, info: nil, exp: nil)
+    def issue_channel_token(sub:, channel:, info: nil, exp: nil)
       payload = {
-        'client' => client,
+        'sub' => sub,
         'channel' => channel,
         'info' => info,
         'exp' => exp

spec/cent/notary_spec.rb

@@ -83,21 +83,21 @@
 
   describe '#issue_channel_token' do
     subject(:channel_token) do
-      notary.issue_channel_token(client: 'client', channel: 'channel', info: { 'foo' => 'bar' })
+      notary.issue_channel_token(sub: '1', channel: 'channel', info: { 'foo' => 'bar' })
     end
 
     let(:notary) { described_class.new(secret: 'secret') }
 
     context 'with no expiration' do
-      it { expect(channel_token).to match(/^eyJhbGciOiJIUzI1NiJ9.*SopvNY$/) }
+      it { expect(channel_token).to match(/^eyJhbGciOiJIUzI1NiJ9.*50TnzY$/) }
     end
 
     context 'with expiration' do
       subject(:channel_token) do
-        notary.issue_channel_token(client: 'client', channel: 'channel', info: { 'foo' => 'bar' }, exp: 1_628_877_060)
+        notary.issue_channel_token(sub: '1', channel: 'channel', info: { 'foo' => 'bar' }, exp: 1_628_877_060)
       end
 
-      it { expect(channel_token).to match(/^eyJhbGciOiJIUzI1NiJ9.*uQCqas$/) }
+      it { expect(channel_token).to match(/^eyJhbGciOiJIUzI1NiJ9.*yht5hk$/) }
     end
 
     context 'with RSA key' do