Avoid confusing error if invalid EC_Group is used

If an unknown group name was passed it would give a PEM error,
instead of saying unknown group.

1 files changed, 9 insertions, 3 deletions

diff --git a/src/lib/pubkey/ec_group/ec_group.cpp b/src/lib/pubkey/ec_group/ec_group.cpp
index 942e7401a..6064f869c 100644
--- a/src/lib/pubkey/ec_group/ec_group.cpp
+++ b/src/lib/pubkey/ec_group/ec_group.cpp
@@ -329,10 +329,16 @@ EC_Group::EC_Group(const std::string& str)
 
    if(m_data == nullptr)
       {
-      // OK try it as PEM ...
-      secure_vector<uint8_t> ber = PEM_Code::decode_check_label(str, "EC PARAMETERS");
-      this->m_data = BER_decode_EC_group(ber.data(), ber.size());
+      if(str.size() > 30 && str.substr(0, 29) == "-----BEGIN EC PARAMETERS-----")
+         {
+         // OK try it as PEM ...
+         secure_vector<uint8_t> ber = PEM_Code::decode_check_label(str, "EC PARAMETERS");
+         this->m_data = BER_decode_EC_group(ber.data(), ber.size());
+         }
       }
+
+   if(m_data == nullptr)
+      throw Invalid_Argument("Unknown ECC group '" + str + "'");
    }
 
 //static