1 files changed, 49 insertions, 7 deletions
diff --git a/src/lib/libstate/lookup.cpp b/src/lib/libstate/lookup.cpp
index 290c266a3..08f0ac866 100644
--- a/src/lib/libstate/lookup.cpp
+++ b/src/lib/libstate/lookup.cpp
@@ -6,8 +6,19 @@
 */
 
 #include <botan/lookup.h>
+#include <botan/cipher_mode.h>
+#include <botan/filters.h>
 #include <botan/libstate.h>
-#include <botan/engine.h>
+#include <botan/parsing.h>
+#include <botan/transform_filter.h>
+
+#if defined(BOTAN_HAS_OFB)
+  #include <botan/ofb.h>
+#endif
+
+#if defined(BOTAN_HAS_CTR_BE)
+  #include <botan/ctr.h>
+#endif
 
 namespace Botan {
 
@@ -82,13 +93,44 @@ Keyed_Filter* get_cipher(const std::string& algo_spec,
    {
    Algorithm_Factory& af = global_state().algorithm_factory();
 
-   Algorithm_Factory::Engine_Iterator i(af);
+   std::unique_ptr<Cipher_Mode> c(get_cipher_mode(algo_spec, direction));
+   if(c)
+      return new Transform_Filter(c.release());
+
+   std::vector<std::string> algo_parts = split_on(algo_spec, '/');
+   if(algo_parts.empty())
+      throw Invalid_Algorithm_Name(algo_spec);
+
+   const std::string cipher_name = algo_parts[0];
+
+   // check if it is a stream cipher first (easy case)
+   const StreamCipher* stream_cipher = af.prototype_stream_cipher(cipher_name);
+   if(stream_cipher)
+      return new StreamCipher_Filter(stream_cipher->clone());
+
+   const BlockCipher* block_cipher = af.prototype_block_cipher(cipher_name);
+   if(!block_cipher)
+      return nullptr;
+
+   if(algo_parts.size() >= 4)
+      return nullptr; // 4 part mode, not something we know about
+
+   if(algo_parts.size() < 2)
+      throw Lookup_Error("Cipher specification '" + algo_spec +
+                         "' is missing mode identifier");
+
+   const std::string mode = algo_parts[1];
+
+
+#if defined(BOTAN_HAS_OFB)
+   if(mode == "OFB")
+      return new StreamCipher_Filter(new OFB(block_cipher->clone()));
+#endif
 
-   while(Engine* engine = i.next())
-      {
-      if(Keyed_Filter* algo = engine->get_cipher(algo_spec, direction, af))
-         return algo;
-      }
+#if defined(BOTAN_HAS_CTR_BE)
+   if(mode == "CTR-BE")
+      return new StreamCipher_Filter(new CTR_BE(block_cipher->clone()));
+#endif
 
    throw Algorithm_Not_Found(algo_spec);
    }