BearSSL: Support for ECDSA

This commit adds support for ECDSA using BearSSL as a backend.  This
means we can test BearSSL's ECDSA algorithms using the extensive
Botan testsuite.

3 files changed, 240 insertions, 0 deletions

diff --git a/src/lib/prov/bearssl/bearssl.h b/src/lib/prov/bearssl/bearssl.h
index d438c47c7..9188770c3 100644
--- a/src/lib/prov/bearssl/bearssl.h
+++ b/src/lib/prov/bearssl/bearssl.h
@@ -30,6 +30,20 @@ class BearSSL_Error : public Exception
 std::unique_ptr<HashFunction>
 make_bearssl_hash(const std::string& name);
 
+/* ECDSA */
+
+#if defined(BOTAN_HAS_ECDSA)
+
+class ECDSA_PublicKey;
+class ECDSA_PrivateKey;
+
+std::unique_ptr<PK_Ops::Verification>
+make_bearssl_ecdsa_ver_op(const ECDSA_PublicKey& key, const std::string& params);
+std::unique_ptr<PK_Ops::Signature>
+make_bearssl_ecdsa_sig_op(const ECDSA_PrivateKey& key, const std::string& params);
+
+#endif
+
 }
 
 #endif
diff --git a/src/lib/prov/bearssl/bearssl_ec.cpp b/src/lib/prov/bearssl/bearssl_ec.cpp
new file mode 100644
index 000000000..507345f24
--- /dev/null
+++ b/src/lib/prov/bearssl/bearssl_ec.cpp
@@ -0,0 +1,192 @@
+/*
+* ECDSA via BearSSL
+* (C) 2015,2016 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/hash.h>
+#include <botan/scan_name.h>
+#include <botan/internal/bearssl.h>
+
+#if defined(BOTAN_HAS_ECC_PUBLIC_KEY_CRYPTO)
+  #include <botan/der_enc.h>
+  #include <botan/pkcs8.h>
+  #include <botan/oids.h>
+  #include <botan/internal/pk_ops_impl.h>
+#endif
+
+#if defined(BOTAN_HAS_ECDSA)
+  #include <botan/ecdsa.h>
+#endif
+
+#include <bearssl_hash.h>
+#include <bearssl_ec.h>
+
+namespace Botan {
+
+#if defined(BOTAN_HAS_ECC_PUBLIC_KEY_CRYPTO)
+
+namespace {
+
+int BearSSL_EC_curve_for(const EC_Group& group)
+   {
+   if(group == EC_Group("secp256r1"))
+      return BR_EC_secp256r1;
+   if(group == EC_Group("secp384r1"))
+      return BR_EC_secp384r1;
+   if(group == EC_Group("secp521r1"))
+      return BR_EC_secp521r1;
+
+   return -1;
+   }
+
+const br_hash_class *BearSSL_hash_class_for(const std::string& emsa)
+   {
+   if (emsa == "EMSA1(SHA-1)")
+      return &br_sha1_vtable;
+   if (emsa == "EMSA1(SHA-224)")
+      return &br_sha224_vtable;
+   if (emsa == "EMSA1(SHA-256)")
+      return &br_sha256_vtable;
+   if (emsa == "EMSA1(SHA-384)")
+      return &br_sha384_vtable;
+   if (emsa == "EMSA1(SHA-512)")
+      return &br_sha512_vtable;
+
+   return NULL;
+   }
+}
+
+#endif
+
+#if defined(BOTAN_HAS_ECDSA) && !defined(OPENSSL_NO_ECDSA)
+
+namespace {
+
+class BearSSL_ECDSA_Verification_Operation : public PK_Ops::Verification
+   {
+   public:
+      BearSSL_ECDSA_Verification_Operation(const ECDSA_PublicKey& ecdsa, const std::string& emsa) :
+         m_order_bits(ecdsa.domain().get_order().bits())
+         {
+         const int curve = BearSSL_EC_curve_for(ecdsa.domain());
+         if (curve < 0)
+            throw Lookup_Error("BearSSL ECDSA does not support this curve");
+
+         m_hash = BearSSL_hash_class_for(emsa);
+         if (m_hash == NULL)
+            throw Lookup_Error("BearSSL ECDSA does not support EMSA " + emsa);
+
+         const SCAN_Name req(emsa);
+         m_hf = make_bearssl_hash(req.arg(0));
+         if (m_hf == NULL)
+            throw Lookup_Error("BearSSL ECDSA does not support hash " + req.arg(0));
+
+         const secure_vector<uint8_t> enc = EC2OSP(ecdsa.public_point(), PointGFp::UNCOMPRESSED);
+         m_key.qlen = enc.size();
+         m_key.q = new uint8_t[m_key.qlen];
+         memcpy(m_key.q, (unsigned char *)enc.data(), m_key.qlen);
+         m_key.curve = curve;
+         }
+
+      void update(const uint8_t msg[], size_t msg_len) override
+         {
+         m_hf->update(msg, msg_len);
+         }
+
+      bool is_valid_signature(const uint8_t sig[], size_t sig_len) override
+         {
+         const size_t order_bytes = (m_order_bits + 7) / 8;
+         if (sig_len != 2 * order_bytes)
+            return false;
+         secure_vector<uint8_t> msg = m_hf->final();
+
+         br_ecdsa_vrfy engine = br_ecdsa_vrfy_raw_get_default();
+         if (!engine(&br_ec_prime_i31, msg.data(), msg.size(), &m_key, sig, sig_len))
+             return false;
+
+         return true;
+         }
+
+      size_t max_input_bits() const { return m_order_bits; }
+
+   private:
+      br_ec_public_key m_key;
+      std::unique_ptr<HashFunction> m_hf;
+      const br_hash_class *m_hash;
+      size_t m_order_bits;
+   };
+
+class BearSSL_ECDSA_Signing_Operation : public PK_Ops::Signature
+   {
+   public:
+      BearSSL_ECDSA_Signing_Operation(const ECDSA_PrivateKey& ecdsa, const std::string& emsa) :
+         m_order_bits(ecdsa.domain().get_order().bits())
+         {
+         const int curve = BearSSL_EC_curve_for(ecdsa.domain());
+         if(curve < 0)
+            throw Lookup_Error("BearSSL ECDSA does not support this curve");
+
+         m_hash = BearSSL_hash_class_for(emsa);
+         if (m_hash == NULL)
+            throw Lookup_Error("BearSSL ECDSA does not support EMSA " + emsa);
+
+         const SCAN_Name req(emsa);
+         m_hf = make_bearssl_hash(req.arg(0));
+         if (m_hf == NULL)
+            throw Lookup_Error("BearSSL ECDSA does not support hash " + req.arg(0));
+
+         m_key.xlen = ecdsa.private_value().bytes();
+         m_key.x = new uint8_t[m_key.xlen];
+         ecdsa.private_value().binary_encode(m_key.x);
+         m_key.curve = curve;
+         }
+
+
+      void update(const uint8_t msg[], size_t msg_len) override
+         {
+         m_hf->update(msg, msg_len);
+         }
+
+      secure_vector<uint8_t> sign(RandomNumberGenerator&) override
+         {
+         const size_t order_bytes = (m_order_bits + 7) / 8;
+         secure_vector<uint8_t> sigval(2*order_bytes);
+         size_t sign_len;
+
+         br_ecdsa_sign engine = br_ecdsa_sign_raw_get_default();
+         sign_len = engine(&br_ec_prime_i31, m_hash, m_hf->final().data(), &m_key, sigval.data());
+         if (sign_len == 0)
+            throw BearSSL_Error("br_ecdsa_sign");
+
+         sigval.resize(sign_len);
+         return sigval;
+         }
+
+      size_t max_input_bits() const { return m_order_bits; }
+
+   private:
+      br_ec_private_key m_key;
+      std::unique_ptr<HashFunction> m_hf;
+      const br_hash_class *m_hash;
+      size_t m_order_bits;
+   };
+
+}
+
+std::unique_ptr<PK_Ops::Verification>
+make_bearssl_ecdsa_ver_op(const ECDSA_PublicKey& key, const std::string& params)
+   {
+   return std::unique_ptr<PK_Ops::Verification>(new BearSSL_ECDSA_Verification_Operation(key, params));
+   }
+
+std::unique_ptr<PK_Ops::Signature>
+make_bearssl_ecdsa_sig_op(const ECDSA_PrivateKey& key, const std::string& params)
+   {
+   return std::unique_ptr<PK_Ops::Signature>(new BearSSL_ECDSA_Signing_Operation(key, params));
+   }
+
+#endif
+
+}
diff --git a/src/lib/pubkey/ecdsa/ecdsa.cpp b/src/lib/pubkey/ecdsa/ecdsa.cpp
index bb65fb138..72551c8c7 100644
--- a/src/lib/pubkey/ecdsa/ecdsa.cpp
+++ b/src/lib/pubkey/ecdsa/ecdsa.cpp
@@ -18,6 +18,10 @@
   #include <botan/rfc6979.h>
 #endif
 
+#if defined(BOTAN_HAS_BEARSSL)
+  #include <botan/internal/bearssl.h>
+#endif
+
 #if defined(BOTAN_HAS_OPENSSL)
   #include <botan/internal/openssl.h>
 #endif
@@ -156,6 +160,21 @@ std::unique_ptr<PK_Ops::Verification>
 ECDSA_PublicKey::create_verification_op(const std::string& params,
                                         const std::string& provider) const
    {
+#if defined(BOTAN_HAS_BEARSSL)
+   if(provider == "bearssl" || provider.empty())
+      {
+      try
+         {
+         return make_bearssl_ecdsa_ver_op(*this, params);
+         }
+      catch(Lookup_Error& e)
+         {
+         if(provider == "bearssl")
+            throw;
+         }
+      }
+#endif
+
 #if defined(BOTAN_HAS_OPENSSL)
    if(provider == "openssl" || provider.empty())
       {
@@ -182,6 +201,21 @@ ECDSA_PrivateKey::create_signature_op(RandomNumberGenerator& /*rng*/,
                                       const std::string& params,
                                       const std::string& provider) const
    {
+#if defined(BOTAN_HAS_BEARSSL)
+   if(provider == "bearssl" || provider.empty())
+      {
+      try
+         {
+         return make_bearssl_ecdsa_sig_op(*this, params);
+         }
+      catch(Lookup_Error& e)
+         {
+         if(provider == "bearssl")
+            throw;
+         }
+      }
+#endif
+
 #if defined(BOTAN_HAS_OPENSSL)
    if(provider == "openssl" || provider.empty())
       {