- Updated examples to use appropriate sizes for larger RSA keys (up to 16k)

diff --git a/programs/pkey/rsa_verify_pss.c b/programs/pkey/rsa_verify_pss.c
index 3c90877..ccac58d 100644
--- a/programs/pkey/rsa_verify_pss.c
+++ b/programs/pkey/rsa_verify_pss.c
@@ -63,7 +63,7 @@
     size_t i;
     rsa_context rsa;
     unsigned char hash[20];
-    unsigned char buf[512];
+    unsigned char buf[POLARSSL_MPI_MAX_SIZE];
     char filename[512];
 
     ret = 1;