Support for ElGamal in FFI interface

* Adds `botan_pubkey_load_elgamal' and `botan_privkey_load_elgamal'
  functions to FFI interface.
* Adds test `ffi_test_elgamal'

1 files changed, 52 insertions, 0 deletions

diff --git a/src/lib/ffi/ffi.cpp b/src/lib/ffi/ffi.cpp
index 7cf69efb3..8e341d83d 100644
--- a/src/lib/ffi/ffi.cpp
+++ b/src/lib/ffi/ffi.cpp
@@ -26,6 +26,7 @@
 #include <botan/reducer.h>
 #include <botan/numthry.h>
 #include <botan/divide.h>
+#include <botan/elgamal.h>
 #include <cstring>
 #include <memory>
 
@@ -1422,6 +1423,57 @@ int botan_pubkey_load_dsa(botan_pubkey_t* key,
 #endif
    }
 
+int botan_pubkey_load_elgamal(botan_pubkey_t* key,
+                              botan_mp_t p, botan_mp_t g, botan_mp_t y)
+   {
+#if defined(BOTAN_HAS_ELGAMAL)
+   *key = nullptr;
+   try
+      {
+      Botan::DL_Group group(safe_get(p), safe_get(g));
+      *key = new botan_pubkey_struct(new Botan::ElGamal_PublicKey(group, safe_get(y)));
+      return 0;
+      }
+   catch(std::exception& exn)
+      {
+      log_exception(BOTAN_CURRENT_FUNCTION, exn.what());
+      }
+
+   return -1;
+#else
+   BOTAN_UNUSED(p);
+   BOTAN_UNUSED(q);
+   BOTAN_UNUSED(g);
+   BOTAN_UNUSED(x);
+   return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
+#endif
+   }
+
+int botan_privkey_load_elgamal(botan_privkey_t* key,
+                               botan_mp_t p, botan_mp_t g, botan_mp_t x)
+   {
+#if defined(BOTAN_HAS_ELGAMAL)
+   *key = nullptr;
+   try
+      {
+      Botan::Null_RNG null_rng;
+      Botan::DL_Group group(safe_get(p), safe_get(g));
+      *key = new botan_privkey_struct(new Botan::ElGamal_PrivateKey(null_rng, group, safe_get(x)));
+      return 0;
+      }
+   catch(std::exception& e)
+      {
+      log_exception(BOTAN_CURRENT_FUNCTION, e.what());
+      }
+   return -1;
+#else
+   BOTAN_UNUSED(p);
+   BOTAN_UNUSED(g);
+   BOTAN_UNUSED(x);
+   return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
+#endif
+   }
+
 namespace {
 
 Botan::BigInt botan_pubkey_do_get_field(const Botan::Public_Key& key,