  It is well known that search SVP is equivalent to optimization SVP. However,
the former reduction from search SVP to optimization SVP by Kannan needs
polynomial times calls to the oracle that solves the optimization SVP. In this
paper, a new rank-preserving reduction is presented with only one call to the
optimization SVP oracle. It is obvious that the new reduction needs the least
calls, and improves Kannan's classical result. What's more, the idea also leads
a similar direct reduction from search CVP to optimization CVP with only one
call to the oracle.
