In one example in accordance with the present disclosure, a method may include receiving, by a processor on a system on a chip (SoC), a request to encrypt a subset of data accessed by a process. The method may also include receiving, at a page encryption hardware unit of the SoC, a system call from an operating system on behalf of the process, to generate an encrypted memory page corresponding to the subset of data. The method may also include generating, by the page encryption hardware unit, an encryption/decryption key for the first physical memory address. The encryption/decryption key may not be accessible by the operating system. The method may also include encrypting, by the page encryption hardware unit, the subset of data to the physical memory address using the encryption/decryption key and storing, by the page encryption hardware unit, the encryption/decryption key in a key store.