1 files changed, 58 insertions, 0 deletions
diff --git a/src/engine/openssl/ossl_dh.cpp b/src/engine/openssl/ossl_dh.cpp
new file mode 100644
index 000000000..290b95622
--- /dev/null
+++ b/src/engine/openssl/ossl_dh.cpp
@@ -0,0 +1,58 @@
+/*************************************************
+* OpenSSL Engine Source File                     *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/eng_ossl.h>
+#include <botan/bn_wrap.h>
+#include <openssl/opensslv.h>
+
+#if OPENSSL_VERSION_NUMBER < 0x0090700F
+  #error Your OpenSSL install is too old, upgrade to 0.9.7 or later
+#endif
+
+namespace Botan {
+
+#if defined(BOTAN_HAS_DIFFIE_HELLMAN)
+
+namespace {
+
+/*************************************************
+* OpenSSL DH Operation                           *
+*************************************************/
+class OpenSSL_DH_Op : public DH_Operation
+   {
+   public:
+      BigInt agree(const BigInt& i) const;
+      DH_Operation* clone() const { return new OpenSSL_DH_Op(*this); }
+
+      OpenSSL_DH_Op(const DL_Group& group, const BigInt& x_bn) :
+         x(x_bn), p(group.get_p()) {}
+   private:
+      OSSL_BN x, p;
+      OSSL_BN_CTX ctx;
+   };
+
+/*************************************************
+* OpenSSL DH Key Agreement Operation             *
+*************************************************/
+BigInt OpenSSL_DH_Op::agree(const BigInt& i_bn) const
+   {
+   OSSL_BN i(i_bn), r;
+   BN_mod_exp(r.value, i.value, x.value, p.value, ctx.value);
+   return r.to_bigint();
+   }
+
+}
+
+/*************************************************
+* Acquire a DH op                                *
+*************************************************/
+DH_Operation* OpenSSL_Engine::dh_op(const DL_Group& group,
+                                    const BigInt& x) const
+   {
+   return new OpenSSL_DH_Op(group, x);
+   }
+#endif
+
+}