The present invention provides methods and apparatuses for verifying that a transaction is legitimate. The methods and apparatuses use protected memory space, such as kernel space of an operating system, or a separate memory space, such as is available on a SIM card of a cellular phone. The method of the invention proceeds by creating a transaction identification string (TID) and associating the TID with a transaction. The TID contains data relevant to or associated with the transaction and is typically readable by an end-user. The transaction is then interrupted until a user responds in the affirmative to allow completion of the transaction. Methods and devices used in the invention are particularly well suited to M-commerce, where transactions originating from a device are typically recognized by a merchant as coming from the owner of the device without further authentication.