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* mpi/mpi-pow.c (mpi_powm): Always perform the mpi_mul for exponents hold in secure memory. -- The attack is described in a paper to be pusblished at eprint.iacr.org: Flush+Reload: a High Resolution, Low Noise, L3 Cache Side-Channel Attack by Yuval Yarom and Katrina Falkner. 18 July 2013. Flush+Reload is a cache side-channel attack that monitors access to data in shared pages. In this paper we demonstrate how to use the attack to extract private encryption keys from GnuPG. The high resolution and low noise of the Flush+Reload attack enables a spy program to recover over 98% of the bits of the private key in a single decryption or signing round. Unlike previous attacks, the attack targets the last level L3 cache. Consequently, the spy program and the victim do not need to share the execution core of the CPU. The attack is not limited to a traditional OS and can be used in a virtualised environment, where it can attack programs executing in a different VM. Signed-off-by: Werner Koch <wk@gnupg.org>