Clarification regarding design of a device.

[mindentropy]

Hi,

   I have say a crypto device and if I pass a data stream assuming echo "test" 
> /dev/aes and when I read it I get an encrypted output. Now if a program 
opens the same device twice should and pass different streams should I 
differentiate those 2 streams and have encrypted buffers of these 2 streams as 
output? If yes how should I differentiate it? Or should I not differentiate and 
provide different devices say aes0,aes1 or should the userspace program worry 
about locking and sharing of resource?

Thanks.