Enhance Signature

lib/hubspot/helpers/signature.rb

@@ -4,22 +4,33 @@
 module Hubspot
   module Helpers
     class Signature
-      MAX_ALLOWED_TIMESTAMP = 3000
+      MAX_ALLOWED_TIMESTAMP = 300_000
+
+      def timestamp_valid?(timestamp)
+        return false if timestamp.nil?
+
+        begin
+          get_current_timestamp_microseconds - timestamp.to_i < MAX_ALLOWED_TIMESTAMP
+        rescue StandardError
+          false
+        end
+      end
+
       def is_valid(
-        signature: String,
-        client_secret: String,
-        request_body: String,
+        signature:,
+        client_secret:,
+        request_body:,
         http_uri: nil,
         http_method: 'POST',
         signature_version: 'v2',
         timestamp: nil
       )
         if signature_version == "v3"
-          current_time = DateTime.now.strftime("%s").to_i
-          if current_time - timestamp.to_i > MAX_ALLOWED_TIMESTAMP
-            raise InvalidSignatureTimestampError.new(timestamp)
+          unless timestamp_valid?(timestamp)
+            raise InvalidSignatureTimestampError, "Invalid timestamp: #{timestamp}"
           end
         end
+
         hashed_signature = get_signature(
           client_secret: client_secret,
           request_body: request_body,
@@ -29,34 +40,43 @@ def is_valid(
           timestamp: timestamp
         )
 
-        signature == hashed_signature
+        secure_compare(signature, hashed_signature)
+      end
+
+      def get_current_timestamp_microseconds
+        (Time.now.to_f * 1000).to_i
       end
 
       def get_signature(
-        client_secret: String,
-        request_body: String,
-        signature_version: String,
+        client_secret:,
+        request_body:,
+        signature_version:,
         http_uri: nil,
         http_method: "POST",
         timestamp: nil
       )
         case signature_version
-          when "v1"
-            source_string = "#{client_secret}#{request_body}"
-            hash_result = Digest::SHA2.hexdigest(source_string.encode('utf-8'))
-            return hash_result
-          when "v2"
-            source_string =  "#{client_secret}#{http_method}#{http_uri}#{request_body}"
-            hash_result = Digest::SHA2.hexdigest(source_string.encode('utf-8'))
-            return hash_result
-          when "v3"
-            source_string = "#{http_method}#{http_uri}#{request_body}#{timestamp}"
-            hash_result =  OpenSSL::HMAC.base64digest('SHA256', client_secret, source_string.encode('utf-8'))
-            return hash_result
-           else
-             raise InvalidSignatureVersionError.new(signature_version)
+        when "v1"
+          source_string = "#{client_secret}#{request_body}"
+          Digest::SHA2.hexdigest(source_string.encode('utf-8'))
+        when "v2"
+          source_string = "#{client_secret}#{http_method}#{http_uri}#{request_body}"
+          Digest::SHA2.hexdigest(source_string.encode('utf-8'))
+        when "v3"
+          source_string = "#{http_method}#{http_uri}#{request_body}#{timestamp}"
+          OpenSSL::HMAC.base64digest('SHA256', client_secret, source_string.encode('utf-8'))
+        else
+          raise InvalidSignatureVersionError, "Invalid signature version: #{signature_version}"
         end
       end
+
+      def secure_compare(a, b)
+        return false unless a.is_a?(String) && b.is_a?(String) && a.bytesize == b.bytesize
+
+        result = 0
+        a.bytes.zip(b.bytes) { |x, y| result |= x ^ y }
+        result.zero?
+      end
     end
   end
 end

spec/helpers/signature_spec.rb

@@ -7,10 +7,10 @@
   :request_body=> "{'example_field':'example_value'}",
   :url=> "https://www.example.com/webhook_uri",
   :http_method=> "POST",
-  :timestamp=> 15000000,
+  :timestamp=> 1_700_000_300_000,
   :v1_hash=> "69fc6631a867edd4f9e9e627fc5c1148e3fbdd8b21837b6d2b8901c1fa57f750",
   :v2_hash=> "4fe4e3a7d3cf09db53be39d0a58130e2aaba074ec123a9e355b876a689a1c383",
-  :v3_hash=> "HPW73RUtKmcYoEDADG0s6MmGFWUzWJKAW07r8RDgcQw=",
+  :v3_hash=> "RnbPH7+UMKVkbV32P8bz450N4M56aPmcru1+D3kSDtw=",
 }
 
 
@@ -77,12 +77,12 @@
     expect(result).to be true
   end
   it "should return true for v3 signature version" do
-    test_timestamp = DateTime.now.strftime("%s")
+    test_timestamp_microseconds = (Time.now.to_f * 1000).to_i
     test_signature = signature.get_signature(
       client_secret: TEST_DATA[:client_secret],
       request_body: TEST_DATA[:request_body],
       http_uri: TEST_DATA[:http_uri],
-      timestamp: test_timestamp,
+      timestamp: test_timestamp_microseconds,
       signature_version: "v3"
     )
 
@@ -91,7 +91,7 @@
       client_secret: TEST_DATA[:client_secret],
       request_body: TEST_DATA[:request_body],
       http_uri: TEST_DATA[:http_uri],
-      timestamp: test_timestamp,
+      timestamp: test_timestamp_microseconds,
       signature_version: "v3"
     )
     expect(result).to be true
@@ -105,6 +105,16 @@
       signature_version: "v3"
     ) }.to raise_error(Hubspot::InvalidSignatureTimestampError)
   end
+  it "should raise exception if :signature_version=>v3 and :timestamp=>expired" do
+    expect {  signature.is_valid(
+      signature: TEST_DATA[:v3_hash],
+      client_secret: TEST_DATA[:client_secret],
+      request_body: TEST_DATA[:request_body],
+      http_uri: TEST_DATA[:http_uri],
+      timestamp: 1_700_000_000_000,
+      signature_version: "v3"
+    ) }.to raise_error(Hubspot::InvalidSignatureTimestampError)
+  end
   it "should raise exception if :signature_version=>v3 and :timestamp=>wrong_timestamp" do
     expect {  signature.is_valid(
       signature: TEST_DATA[:v3_hash],