- The secrecy capacity of the multiantenna wiretap channel was recently characterized independently by Khisti and Wornell and Oggier and Hassibi using a Sato-like argument and matrix analysis tools. This paper presents an alternative characterization of the secrecy capacity of the multiantenna wiretap channel using a channel-enhancement argument. Compared with the approach of Khisti-Wornell and Oggier-Hassibi, this characterization is by nature information- rather than matrixtheoretic. Moreover, it extends the previous results from the average total power constraint to the more general matrix power constraint. 2009 IEEE.