tree b72b35d77908a5489e4ccd638618b23f0e0a9115
parent e0e7ddf99e3e8767fc276c2c30aebbb9056bdb3f
author Darryl Green <darryl.green@arm.com> 1538482895 +0100
committer Darryl Green <darryl.green@arm.com> 1539099413 +0100

Fix bias in random number generation in Miller-Rabin test

When a random number is generated for the Miller-Rabin primality test,
if the bit length of the random number is larger than the number being
tested, the random number is shifted right to have the same bit length.
This introduces bias, as the random number is now guaranteed to be
larger than 2^(bit length-1).

Changing this to instead zero all bits higher than the tested numbers
bit length will remove this bias and keep the random number being
uniformly generated.