EC_PublicKey::check_key for curves with cofactor > 1

1 files changed, 24 insertions, 1 deletions

diff --git a/src/lib/pubkey/ecc_key/ecc_key.cpp b/src/lib/pubkey/ecc_key/ecc_key.cpp
index cb0af42eb..fd1e9dd83 100644
--- a/src/lib/pubkey/ecc_key/ecc_key.cpp
+++ b/src/lib/pubkey/ecc_key/ecc_key.cpp
@@ -47,9 +47,32 @@ EC_PublicKey::EC_PublicKey(const AlgorithmIdentifier& alg_id,
 bool EC_PublicKey::check_key(RandomNumberGenerator&,
                              bool) const
    {
-   return public_point().on_the_curve();
+   //check that public point is not at infinity
+   if(public_point().is_zero())
+      {
+      return false;
+      }
+   //check that public point is on the curve
+   if(!public_point().on_the_curve())
+      {
+      return false;
+      }
+   if(m_domain_params.get_cofactor() > 1)
+      {
+      if((public_point() * m_domain_params.get_cofactor()).is_zero())
+         {
+         return false;
+         }
+      //check that public point has order q
+      if(!(public_point() * m_domain_params.get_order()).is_zero())
+         {
+         return false;
+         }
+      }
+   return true;
    }
 
+
 AlgorithmIdentifier EC_PublicKey::algorithm_identifier() const
    {
    return AlgorithmIdentifier(get_oid(), DER_domain());