Adds optional XMSS WOTS stand-alone components

The main XMSS implementation does not expose stand-alone access to XMSS
Winternitz One Time Signatures through the Botan::PK_Ops interfaces.
XMSS WOTS is used by XMSS internally though. This PR implements a
possible XMSS WOTS interface for stand-alone use.

XMSS WOTS is tested through the XMSS tests, therefore there are no
dedicated XMSS WOTS test vectors and test bench components implemented
in this PR.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/lib/pubkey/xmss/xmss_wots_privatekey.cpp b/src/lib/pubkey/xmss/xmss_wots_privatekey.cpp
index 1a68b187d..13568e0b9 100644
--- a/src/lib/pubkey/xmss/xmss_wots_privatekey.cpp
+++ b/src/lib/pubkey/xmss/xmss_wots_privatekey.cpp
@@ -8,6 +8,7 @@
  * Botan is released under the Simplified BSD License (see license.txt)
  **/
 
+#include <botan/internal/xmss_wots_signature_operation.h>
 #include <botan/xmss_wots_privatekey.h>
 
 namespace Botan {
@@ -77,4 +78,16 @@ XMSS_WOTS_PrivateKey::sign(
    return sig;
    }
 
+std::unique_ptr<PK_Ops::Signature>
+XMSS_WOTS_PrivateKey::create_signature_op(RandomNumberGenerator&,
+                                          const std::string&,
+                                          const std::string& provider) const
+   {
+   if(provider == "base" || provider.empty())
+      return std::unique_ptr<PK_Ops::Signature>(
+           new XMSS_WOTS_Signature_Operation(*this));
+
+   throw Provider_Not_Found(algo_name(), provider);
+   }
+
 }