Add parameter validation XTS setkey functions
diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index 11edc0f..197d4db 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -197,8 +197,10 @@
* sets the encryption key.
*
* \param ctx The AES XTS context to which the key should be bound.
+ * It must be initialized.
* \param key The encryption key. This is comprised of the XTS key1
* concatenated with the XTS key2.
+ * This must be a readable buffer of size \p keybits bits.
* \param keybits The size of \p key passed in bits. Valid options are:
* <ul><li>256 bits (each of key1 and key2 is a 128-bit key)</li>
* <li>512 bits (each of key1 and key2 is a 256-bit key)</li></ul>
@@ -215,8 +217,10 @@
* sets the decryption key.
*
* \param ctx The AES XTS context to which the key should be bound.
+ * It must be initialized.
* \param key The decryption key. This is comprised of the XTS key1
* concatenated with the XTS key2.
+ * This must be a readable buffer of size \p keybits bits.
* \param keybits The size of \p key passed in bits. Valid options are:
* <ul><li>256 bits (each of key1 and key2 is a 128-bit key)</li>
* <li>512 bits (each of key1 and key2 is a 256-bit key)</li></ul>