Add pk_rsa_set_padding() and rsa_set_padding()
diff --git a/library/rsa.c b/library/rsa.c
index 8ec7aab..75cae7e 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -60,6 +60,17 @@
 #endif
 }
 
+/*
+ * Set padding method after initialisation
+ */
+void rsa_set_padding( rsa_context *ctx,
+                      int padding,
+                      int hash_id)
+{
+    ctx->padding = padding;
+    ctx->hash_id = hash_id;
+}
+
 #if defined(POLARSSL_GENPRIME)
 
 /*