I read here a paper of Daniel Bernstein
This paper demonstrate complete AES key recovery from known-plaintext timing of a network server of another computer. This attack should be blamed on the AES design not on the particular AES library used by the server. It is extremely difficult to write constant-time high-speed AES software for common general-purpose computers
There is countermeasures for new processors and architectures ?
Why is so o write constant-time high-speed AES software for common general-purpose computers ? What is the problem ?