diff --git a/lang/cpp/src/verificationresult.cpp b/lang/cpp/src/verificationresult.cpp
index a7b073e6..23c458e1 100644
--- a/lang/cpp/src/verificationresult.cpp
+++ b/lang/cpp/src/verificationresult.cpp
@@ -29,6 +29,7 @@
 #include "result_p.h"
 #include "util.h"
 #include "key.h"
+#include "context.h"
 
 #include <gpgme.h>
 
@@ -121,6 +122,7 @@ public:
     std::vector<GpgME::Key> keys;
     std::vector<char *> purls;
     std::string file_name;
+    Protocol proto;
 };
 
 GpgME::VerificationResult::VerificationResult(gpgme_ctx_t ctx, int error)
@@ -145,6 +147,10 @@ void GpgME::VerificationResult::init(gpgme_ctx_t ctx)
         return;
     }
     d.reset(new Private(res));
+    gpgme_protocol_t proto = gpgme_get_protocol(ctx);
+    d->proto = proto == GPGME_PROTOCOL_OpenPGP ? OpenPGP :
+               proto == GPGME_PROTOCOL_CMS ? CMS :
+               UnknownProtocol;
 }
 
 make_standard_stuff(VerificationResult)
@@ -386,6 +392,32 @@ GpgME::Key GpgME::Signature::key() const
     return d->keys[idx];
 }
 
+GpgME::Key GpgME::Signature::key(bool search, bool update) const
+{
+    if (isNull()) {
+        return Key();
+    }
+
+    GpgME::Key ret = key();
+    if (ret.isNull() && search) {
+        auto ctx = Context::createForProtocol (d->proto);
+        if (ctx) {
+            ctx->setKeyListMode(KeyListMode::Local |
+                        KeyListMode::Signatures |
+                        KeyListMode::SignatureNotations |
+                        KeyListMode::Validate |
+                        KeyListMode::WithTofu);
+            Error e;
+            ret = d->keys[idx] = ctx->key(fingerprint(), e, false);
+            delete ctx;
+        }
+    }
+    if (update) {
+        ret.update();
+    }
+    return ret;
+}
+
 class GpgME::Notation::Private
 {
 public:
diff --git a/lang/cpp/src/verificationresult.h b/lang/cpp/src/verificationresult.h
index 93288af2..b6d1d8ce 100644
--- a/lang/cpp/src/verificationresult.h
+++ b/lang/cpp/src/verificationresult.h
@@ -163,6 +163,27 @@ public:
      * set or the associated TOFU Information if applicable. */
     GpgME::Key key() const;
 
+    /* Search / Update the key of this signature.
+     *
+     * Same as above but if search is set to true this will
+     * either update the key provided by the engine or search
+     * the key in the engine. The key is cached.
+     *
+     * As this involves an engine call it might take some time
+     * to finish so it should be avoided to do this in a UI
+     * thread. The result will be cached and no engine call
+     * will be done if update is set to false and a key is
+     * already cached.
+     *
+     * If no key was provided by the engine this will look
+     * up the key so this call might block while the engine
+     * is called to obtain the key.
+     *
+     * If both search and update are false this is the same
+     * as calling key()
+     */
+    GpgME::Key key(bool search, bool update) const;
+
 private:
     std::shared_ptr<VerificationResult::Private> d;
     unsigned int idx;