More pubkey doc updates

1 files changed, 62 insertions, 0 deletions

diff --git a/doc/examples/dh.cpp b/doc/examples/dh.cpp
new file mode 100644
index 000000000..8489df8fe
--- /dev/null
+++ b/doc/examples/dh.cpp
@@ -0,0 +1,62 @@
+#include <botan/botan.h>
+#include <botan/dh.h>
+#include <botan/pubkey.h>
+using namespace Botan;
+
+#include <iostream>
+#include <memory>
+
+int main()
+   {
+   try
+      {
+      LibraryInitializer init;
+
+      AutoSeeded_RNG rng;
+
+      // Alice and Bob agree on a DH domain to use
+      DL_Group shared_domain("modp/ietf/2048");
+
+      // Alice creates a DH key
+      DH_PrivateKey private_a(rng, shared_domain);
+
+      // Bob creates a key with a matching group
+      DH_PrivateKey private_b(rng, shared_domain);
+
+      // Alice sends to Bob her public key and a session parameter
+      MemoryVector<byte> public_a = private_a.public_value();
+      const std::string session_param =
+         "Alice and Bob's shared session parameter";
+
+      // Bob sends his public key to Alice
+      MemoryVector<byte> public_b = private_b.public_value();
+
+      // Now Alice performs the key agreement operation
+      PK_Key_Agreement ka_alice(private_a, "KDF2(SHA-256)");
+      SymmetricKey alice_key = ka1.derive_key(32, public_b, session_param);
+
+      // Bob does the same:
+      PK_Key_Agreement ka_bob(private_b, "KDF2(SHA-256)");
+      SymmetricKey bob_key = ka2.derive_key(32, public_a, session_param);
+
+      if(alice_key == bob_key)
+         {
+         std::cout << "The two keys matched, everything worked\n";
+         std::cout << "The shared key was: " << alice_key.as_string() << "\n";
+         }
+      else
+         {
+         std::cout << "The two keys didn't match! Hmmm...\n";
+         std::cout << "Alice's key was: " << alice_key.as_string() << "\n";
+         std::cout << "Bob's key was: " << bob_key.as_string() << "\n";
+         }
+
+      // Now use the shared key for encryption or MACing or whatever
+   }
+   catch(std::exception& e)
+      {
+      std::cout << e.what() << std::endl;
+      return 1;
+      }
+   return 0;
+   }