Fix ommission in pk_free().
diff --git a/library/pk.c b/library/pk.c
index ca99fc6..edbbf50 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -66,6 +66,8 @@
             break;
     }
 
+    free( ctx-> data );
+
     ctx->type = POLARSSL_PK_NONE;
     ctx->data = NULL;
 }