catch C++ exception from malformed serialized signing key and turn it into Python exception

fixes #83

2 files changed, 7 insertions, 2 deletions

diff --git a/src/pycryptopp/publickey/rsamodule.cpp b/src/pycryptopp/publickey/rsamodule.cpp
index 3e83803..256fd85 100644
--- a/src/pycryptopp/publickey/rsamodule.cpp
+++ b/src/pycryptopp/publickey/rsamodule.cpp
@@ -354,7 +354,12 @@ rsa_create_signing_key_from_string(PyObject *dummy, PyObject *args, PyObject *kw
         return NULL;
     StringSource ss(reinterpret_cast<const byte*>(serializedsigningkey), serializedsigningkeysize, true);
 
-    signer->k = new RSASS<PSS, SHA256>::Signer(ss);
+    try {
+        signer->k = new RSASS<PSS, SHA256>::Signer(ss);
+    } catch (CryptoPP::BERDecodeErr le) {
+        return PyErr_Format(rsa_error, "Serialized signing key was corrupted.  Crypto++ gave this exception: %s", le.what());
+    }
+
     if (!signer->k)
         return PyErr_NoMemory();
     return reinterpret_cast<PyObject*>(signer);
diff --git a/src/pycryptopp/test/test_rsa.py b/src/pycryptopp/test/test_rsa.py
index 5348789..5370f16 100644
--- a/src/pycryptopp/test/test_rsa.py
+++ b/src/pycryptopp/test/test_rsa.py
@@ -54,7 +54,7 @@ class Signer(unittest.TestCase):
 
     def test_create_from_string_invalid(self):
         try:
-            signer = rsa.create_signing_key_from_string("invalid string")
+            rsa.create_signing_key_from_string("invalid string")
         except rsa.Error, le:
             self.failUnless("decode error" in str(le), le)
         else: