The present disclosure is directed to systems and methods for providing protection against replay attacks on memory, by refreshing or updating encryption keys. The disclosed replay protected computing system may employ encryption refresh of memory so that unauthorized copies of data are usable for a limited amount of time (e.g., 500 milliseconds or less). The replay protected computing system initially encrypts protected data prior to storage in memory. After a predetermined time or after a number of memory accesses have occurred, the replay protected computing system decrypts the data with the existing key and re-encrypts data with a new key. Unauthorized copies of data (such as those made by an adversary system/program) are not refreshed with subsequent new keys. When an adversary program attempts to use the unauthorized copies of data, the unauthorized copies of data are decrypted with the incorrect keys, which renders the decrypted data unintelligible.