feat: add sha256 signatures to outgoing http requests (#2874)

lib/postal/config.rb

@@ -98,12 +98,15 @@ module Postal
       "#{locker_name} #{suffix}"
     end
 
-    def signing_key
-      @signing_key ||= OpenSSL::PKey::RSA.new(File.read(Config.postal.signing_key_path))
+    def signer
+      @signer ||= begin
+        key = OpenSSL::PKey::RSA.new(File.read(Config.postal.signing_key_path))
+        Signer.new(key)
+      end
     end
 
     def rp_dkim_dns_record
-      public_key = signing_key.public_key.to_s.gsub(/-+[A-Z ]+-+\n/, "").gsub(/\n/, "")
+      public_key = signer.private_key.public_key.to_s.gsub(/-+[A-Z ]+-+\n/, "").gsub(/\n/, "")
       "v=DKIM1; t=s; h=sha256; p=#{public_key};"
     end
 

lib/postal/http.rb

@@ -40,8 +40,9 @@ module Postal
       end
 
       if options[:sign]
-        signature = EncryptoSigno.sign(Postal.signing_key, request.body.to_s).gsub("\n", "")
-        request.add_field "X-Postal-Signature", signature
+        request.add_field "X-Postal-Signature-KID", Postal.signer.jwk.kid
+        request.add_field "X-Postal-Signature", Postal.signer.sha1_sign64(request.body.to_s)
+        request.add_field "X-Postal-Signature-256", Postal.signer.sign64(request.body.to_s)
       end
 
       request["User-Agent"] = options[:user_agent] || "Postal/#{Postal.version}"