cpp: Allow setting the curve to use when generating ECC keys

lang/cpp/src/gpggencardkeyinteractor.h (class GpgGenCardKeyInteractor):
Add enum Curve. Add member function setCurve.
lang/cpp/src/gpggencardkeyinteractor.cpp
(class GpgGenCardKeyInteractor::Private): Initialize simple members
in-class. Add member curve.
(GpgGenCardKeyInteractor::~GpgGenCardKeyInteractor): Use default d'tor.
(GpgGenCardKeyInteractor::setCurve): New.
(GpgGenCardKeyInteractor::action): Return curve defaulting to
Curve25519.
--

This enables users of this interactor to request the generation of
ECC keys with a specific curve as smart card keys. It's up to the user
to specify a curve that is actually supported by the smart card.

GnuPG-bug-id: 4429

1 files changed, 18 insertions, 1 deletions

diff --git a/lang/cpp/src/gpggencardkeyinteractor.h b/lang/cpp/src/gpggencardkeyinteractor.h
index 3d9c7136..09a73b6a 100644
--- a/lang/cpp/src/gpggencardkeyinteractor.h
+++ b/lang/cpp/src/gpggencardkeyinteractor.h
@@ -58,10 +58,27 @@ public:
 
     enum Algo {
         RSA = 1,
-        ECC = 2
+        ECC = 2,
     };
     void setAlgo(Algo algo);
 
+    // the enum values minus 1 have to match the indexes of the curves used by
+    // ask_curve() in gnupg's g10/keygen.c
+    enum Curve {
+        DefaultCurve = 0, // currently Curve25519
+        Curve25519 = 1,
+        Curve448,
+        NISTP256,
+        NISTP384,
+        NISTP521,
+        BrainpoolP256,
+        BrainpoolP384,
+        BrainpoolP512,
+        Secp256k1,
+        LastCurve = Secp256k1,
+    };
+    void setCurve(Curve curve);
+
     std::string backupFileName() const;
 
 private: