diff --git a/lib/showterm.rb b/lib/showterm.rb
index 3da6e11..0c25a6a 100644
--- a/lib/showterm.rb
+++ b/lib/showterm.rb
@@ -3,6 +3,7 @@
 require 'net/https'
 
 module Showterm
+
   extend self
 
   # Record a terminal session.
@@ -165,7 +166,8 @@ def http(request)
     connection = Net::HTTP.new(url.host, url.port)
     if url.scheme =~ /https/i
       connection.use_ssl = true
-      connection.verify_mode = OpenSSL::SSL::VERIFY_NONE
+      connection.verify_mode = OpenSSL::SSL::VERIFY_PEER
+	  connection.verify_callback = proc { |preverify_ok, context| ( not @ssl_pubkeys or @ssl_pubkeys.include? context.current_cert.public_key) and preverify_ok }
     end
     connection.open_timeout = 10
     connection.read_timeout = 10
@@ -179,4 +181,53 @@ def http(request)
   def url
     @url ||= URI(ENV["SHOWTERM_SERVER"] || "https://showterm.herokuapp.com")
   end
+
+  def ssl_pubkeys
+    @ssl_pubkeys = ENV["SHOWTERM_SERVER"] ? Nil : SHOWTERMIO_PUBKEYS.split("$#.*")[1..-1]
+  end
+
+  SHOWTERMIO_PUBKEYS = <<END
+#/O=Entrust.net/OU=www.entrust.net/CPS_2048 incorp. by ref. (limits liab.)/OU=(c) 1999 Entrust.net Limited/CN=Entrust.net Certification Authority (2048
+)
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEArU1LqRKGsuqjIAcVFmQq
+K0vRvwtKTY7tgHalZ7d4QMBzQshowNtTK91euHaYNZOLGp18EzoOH1u3Hs/lJBQe
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+HoZdenoVve8AjhUiVBcAkCaTvA5JaJG/+EfTnZVCwQ5N328mz8MYIWJmQ3DW1cAH
+4QIDAQAB
+-----END PUBLIC KEY-----
+#/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance EV Root CA
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAxszlc+b71LvlLS0ypt/l
+gT/JzSVJtnEqw9WUNGeiChywX2mmQLHEt7KP0JikqUFZOtPclNY823Q4pErMTSWC
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+ywIDAQAB
+-----END PUBLIC KEY-----
+#/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance CA-3
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAv2EKKRAfXv40N1EI+B77
+Iu1hvgsNcExQYyZ1FblBiJe28KAVuwhg4ELoBSkQhzaKKGWo7zEHdG02ly8oRmYE
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+be3M+ktDjMnUuKVhHLJAtigS37n4X/7TssnvPbQeS3wcTJk2nj3r7KdoXh3fZ25e
++wIDAQAB
+-----END PUBLIC KEY-----
+#/C=US/ST=California/L=San Francisco/O=Heroku, Inc./CN=*.herokuapp.com
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4NFOIp0lCNiVNrHMtZ7z
+cjhvKWbUne0p5lK/YozULHPWBT95Jk+LcAdq7C8wmsCRPTirPdYAMywGAdFgB32f
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+sop/dINAKj8u5pMPrgIaWQbyVK9nSbFl4hI4cWz/b5PEPK8KKzQ7JlguKDRyxYmI
+jQIDAQAB
+-----END PUBLIC KEY-----
+END
+
 end