White-box cryptography
Cryptography meant to hold even when the attacker can read the program's memory and control its execution.
White-box cryptography answers a question the classic model does not ask: what if the code itself is visible? In 2002 Chow, Eisen, Johnson and van Oorschot showed how an AES key could be embedded in lookup tables so that it never sits in memory in the clear. The technique has been used in DRM and mobile payment schemes.
In practice, designs have been broken several times, because the tables can be analysed and the key recovered. The honest description is that white-box implementations buy time rather than provide a lock.