symmetric.rb in slosilo-0.1.2

- old
+ new
@@ -1,63 +1,33 @@
 module Slosilo
   class Symmetric
-    VERSION_MAGIC = 'G'
-    TAG_LENGTH = 16
-
     def initialize
-      @cipher = OpenSSL::Cipher.new 'aes-256-gcm' # NB: has to be lower case for whatever reason.
-      @cipher_mutex = Mutex.new
+      @cipher = OpenSSL::Cipher.new 'AES-256-CBC'
     end
-
-    # This lets us do a final sanity check in migrations from older encryption versions
-    def cipher_name
-      @cipher.name
-    end
-
+    
     def encrypt plaintext, opts = {}
-      # All of these operations in OpenSSL must occur atomically, so we
-      # synchronize their access to make this step thread-safe.
-      @cipher_mutex.synchronize do
-        @cipher.reset
-        @cipher.encrypt
-        @cipher.key = (opts[:key] or raise("missing :key option"))
-        @cipher.iv = iv = random_iv
-        @cipher.auth_data = opts[:aad] || "" # Nothing good happens if you set this to nil, or don't set it at all
-        ctext = @cipher.update(plaintext) + @cipher.final
-        tag = @cipher.auth_tag(TAG_LENGTH)
-        "#{VERSION_MAGIC}#{tag}#{iv}#{ctext}"
-      end
+      @cipher.reset
+      @cipher.encrypt
+      @cipher.key = opts[:key]
+      @cipher.iv = iv = random_iv
+      ctxt = @cipher.update(plaintext)
+      iv + ctxt + @cipher.final
     end
-
+    
     def decrypt ciphertext, opts = {}
-      version, tag, iv, ctext = unpack ciphertext
-
-      raise "Invalid version magic: expected #{VERSION_MAGIC} but was #{version}" unless version == VERSION_MAGIC
-
-      # All of these operations in OpenSSL must occur atomically, so we
-      # synchronize their access to make this step thread-safe.
-      @cipher_mutex.synchronize do
-        @cipher.reset
-        @cipher.decrypt
-        @cipher.key = opts[:key]
-        @cipher.iv = iv
-        @cipher.auth_tag = tag
-        @cipher.auth_data = opts[:aad] || ""
-        @cipher.update(ctext) + @cipher.final
-      end
+      @cipher.reset
+      @cipher.decrypt
+      @cipher.key = opts[:key]
+      @cipher.iv, ctxt = ciphertext.unpack("a#{@cipher.iv_len}a*")
+      ptxt = @cipher.update(ctxt)
+      ptxt + @cipher.final
     end
-
+    
     def random_iv
       @cipher.random_iv
     end
-
+    
     def random_key
       @cipher.random_key
-    end
-
-    private
-    # return tag, iv, ctext
-    def unpack msg
-      msg.unpack "aa#{TAG_LENGTH}a#{@cipher.iv_len}a*"
     end
   end
 end