1 files changed, 66 insertions, 0 deletions
diff --git a/src/lib/pubkey/xmss/xmss_wots_publickey.cpp b/src/lib/pubkey/xmss/xmss_wots_publickey.cpp
new file mode 100644
index 000000000..aa0240be8
--- /dev/null
+++ b/src/lib/pubkey/xmss/xmss_wots_publickey.cpp
@@ -0,0 +1,66 @@
+/**
+ * XMSS WOTS Public Key
+ * A Winternitz One Time Signature public key for use with Extended Hash-Based
+ * Signatures.
+ *
+ * (C) 2016 Matthias Gierlings
+ *
+ * Botan is released under the Simplified BSD License (see license.txt)
+ **/
+
+#include <botan/xmss_wots_publickey.h>
+
+namespace Botan {
+
+void
+XMSS_WOTS_PublicKey::chain(secure_vector<byte>& result,
+                           size_t start_idx,
+                           size_t steps,
+                           XMSS_Address& adrs,
+                           const secure_vector<byte>& seed)
+   {
+   for(size_t i = start_idx;
+         i < (start_idx + steps) && i < m_wots_params.wots_parameter();
+         i++)
+      {
+      adrs.set_hash_address(i);
+
+      //Calculate tmp XOR bitmask
+      adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Mask_Mode);
+      xor_buf(result, m_hash.prf(seed, adrs.bytes()), result.size());
+
+      // Calculate key
+      adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Key_Mode);
+
+      //Calculate f(key, tmp XOR bitmask)
+      m_hash.f(result, m_hash.prf(seed, adrs.bytes()), result);
+      }
+   }
+
+wots_keysig_t
+XMSS_WOTS_PublicKey::pub_key_from_signature(const secure_vector<byte>& msg,
+      const wots_keysig_t& sig,
+      XMSS_Address& adrs,
+      const secure_vector<byte>& seed)
+   {
+   secure_vector<byte> msg_digest
+      {
+      m_wots_params.base_w(msg, m_wots_params.len_1())
+      };
+
+   m_wots_params.append_checksum(msg_digest);
+   wots_keysig_t result(sig);
+
+   for(size_t i = 0; i < m_wots_params.len(); i++)
+      {
+      adrs.set_chain_address(i);
+      chain(result[i],
+            msg_digest[i],
+            m_wots_params.wots_parameter() - 1 - msg_digest[i],
+            adrs,
+            seed);
+      }
+   return result;
+   }
+
+}