Which android devices have optimized encryption hardware? I've been using a Nexus 5 for a while and using FS encryption. Apple's iOS Security document states that:


  Every iOS device has a dedicated AES 256 crypto engine built into the DMA path
  between the flash storage and main system memory, making file encryption highly
  efficient. Along with the AES engine, SHA-1 is implemented in hardware, further reducing
  cryptographic operation overhead.


Do any of the Android devices have such hardware to reduce encryption overhead? Is it part of a standard like iOS?
Fundamentally Android requires the developer to implement encryption directly (ie, there is no OS supplied framework for this).

To the best of my knowledge, there is no current Android hardware with Encryption built into to the hardware.  The new "Black Phone" that Boeing is reportedly making for the US defense industry is likely an exception to this (the phone HW was specifically engineered for security).

Basically iOS is encrypted by default, and Android requires the devloper to implement encryption in their applications.