Added Extended Hash-Based Signatures (XMSS)

[1] XMSS: Extended Hash-Based Signatures,
    draft-itrf-cfrg-xmss-hash-based-signatures-06
    Release: July 2016.
    https://datatracker.ietf.org/doc/
    draft-irtf-cfrg-xmss-hash-based-signatures/?include_text=1

Provides XMSS_PublicKey and XMSS_PrivateKey classes as well as implementations
for the Botan interfaces PK_Ops::Signature and PK_Ops::Verification. XMSS has
been integrated into the Botan test bench, signature generation and verification
can be tested independently by invoking "botan-test xmss_sign" and
"botan-test xmss_verify"

- Some headers that are not required to be exposed to users of the library have
  to be declared as public in `info.txt`. Declaring those headers private will
  cause the amalgamation build to fail. The following headers have been
  declared public inside `info.txt`, even though they are only intended for
  internal use:
    * atomic.h
    * xmss_hash.h
    * xmss_index_registry.h
    * xmss_address.h
    * xmss_common_ops.h
    * xmss_tools.h
    * xmss_wots_parameters.h
    * xmss_wots_privatekey.h
    * xmss_wots_publickey.h

- XMSS_Verification_Operation Requires the "randomness" parameter out of the
  XMSS signature. "Randomness" is part of the prefix that is hashed *before*
  the message. Since the signature is unknown till sign() is called, all
  message content has to be buffered. For large messages this can be
  inconvenient or impossible.

  **Possible solution**: Change PK_Ops::Verification interface to take
  the signature as constructor argument, and provide a setter method to be able
  to update reuse the instance on multiple signatures. Make sign a parameterless
  member call. This solution requires interface changes in botan.

  **Suggested workaround** for signing large messages is to not sign the message
  itself, but to precompute the message hash manually using Botan::HashFunctio
  and sign the message hash instead of the message itself.

- Some of the available test vectors for the XMSS signature verification have
  been commented out in order to reduce testbench runtime.

1 files changed, 72 insertions, 0 deletions

diff --git a/src/tests/test_xmss.cpp b/src/tests/test_xmss.cpp
new file mode 100644
index 000000000..dd53d9b7f
--- /dev/null
+++ b/src/tests/test_xmss.cpp
@@ -0,0 +1,72 @@
+/**
+ * Extended Hash-Based Signatures Tests
+ *
+ * (C) 2014,2015 Jack Lloyd
+ * (C) 2016 Matthias Gierlings
+ **/
+
+#include "tests.h"
+
+#if defined(BOTAN_HAS_XMSS)
+    #include <botan/xmss.h>
+    #include "test_pubkey.h"
+#endif
+
+namespace Botan_Tests {
+
+namespace {
+
+#if defined(BOTAN_HAS_XMSS)
+
+class XMSS_Signature_Tests : public PK_Signature_Generation_Test
+   {
+   public:
+      XMSS_Signature_Tests() : PK_Signature_Generation_Test(
+         "XMSS",
+         "pubkey/xmss_sig.vec",
+         {"Msg", "PrivateKey", "Signature"},
+         {})
+         {}
+
+      std::string default_padding(const VarMap&) const override { return "Raw"; }
+
+      std::unique_ptr<Botan::Private_Key> load_private_key(const VarMap& vars) override
+         {
+         const std::vector<byte> raw_key = get_req_bin(vars, "PrivateKey");
+         const Botan::secure_vector<byte> sec_key(raw_key.begin(), raw_key.end());
+
+         std::unique_ptr<Botan::Private_Key> key(new Botan::XMSS_PrivateKey(sec_key));
+         return key;
+         }
+   };
+
+class XMSS_Signature_Verify_Tests : public PK_Signature_Verification_Test
+   {
+   public:
+      XMSS_Signature_Verify_Tests() : PK_Signature_Verification_Test(
+         "XMSS",
+         "pubkey/xmss_verify.vec",
+         {"Msg", "PublicKey", "Signature"},
+         {})
+         {}
+
+      std::string default_padding(const VarMap&) const override { return "Raw"; }
+
+      std::unique_ptr<Botan::Public_Key> load_public_key(const VarMap& vars) override
+         {
+	     const std::vector<byte> raw_key = get_req_bin(vars, "PublicKey");
+		 const Botan::secure_vector<byte> sec_key(raw_key.begin(), raw_key.end());
+
+		 std::unique_ptr<Botan::Public_Key> key(new Botan::XMSS_PublicKey(sec_key));
+         return key;
+         }
+   };
+
+BOTAN_REGISTER_TEST("xmss_sign", XMSS_Signature_Tests);
+BOTAN_REGISTER_TEST("xmss_verify", XMSS_Signature_Verify_Tests);
+
+#endif
+
+}
+
+}