Add a runtime map of string->func() which when called return

Transforms and BlockCiphers. Registration for all types is done at
startup but is very cheap as just a std::function and a std::map entry
are created, no actual objects are created until needed. This is a
huge improvement over Algorithm_Factory which used T::clone() as the
function and thus kept a prototype object of each type in memory.

Replace existing lookup mechanisms for ciphers, AEADs, and compression
to use the transform lookup. The existing Engine framework remains in
place for BlockCipher, but the engines now just call to the registry
instead of having hardcoded lookups.

s/Transformation/Transform/ with typedefs for compatability.

Remove lib/selftest code (for runtime selftesting): not the right approach.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/lib/block/cascade/cascade.cpp b/src/lib/block/cascade/cascade.cpp
index 98e862de9..6c0458265 100644
--- a/src/lib/block/cascade/cascade.cpp
+++ b/src/lib/block/cascade/cascade.cpp
@@ -5,10 +5,29 @@
 * Botan is released under the Simplified BSD License (see license.txt)
 */
 
+#include <botan/internal/block_utils.h>
+#include <botan/algo_registry.h>
 #include <botan/cascade.h>
 
 namespace Botan {
 
+namespace {
+
+Cascade_Cipher* make_cascade(const BlockCipher::Spec& spec)
+   {
+   auto& block_cipher = Algo_Registry<BlockCipher>::global_registry();
+   std::unique_ptr<BlockCipher> c1(block_cipher.make(spec.arg(0)));
+   std::unique_ptr<BlockCipher> c2(block_cipher.make(spec.arg(1)));
+
+   if(c1 && c2)
+      return new Cascade_Cipher(c1.release(), c2.release());
+   return nullptr;
+   }
+
+}
+
+BOTAN_REGISTER_NAMED_T(BlockCipher, "Cascade", Cascade_Cipher, make_cascade);
+
 void Cascade_Cipher::encrypt_n(const byte in[], byte out[],
                                size_t blocks) const
    {