question: public static byte [ ] generateKey ( ) { byte [ ] keyData = new byte [ KEY_LENGTH ] ; secureRandom . nextBytes ( keyData ) ; byte [ ] ivData = new byte [ IV_LENGTH ] ; secureRandom . nextBytes ( ivData ) ; byte [ ] key = new byte [ IV_LENGTH + KEY_LENGTH ] ; System . arraycopy ( ivData , 0 , key , 0 , IV_LENGTH ) ; System . arraycopy ( keyData , 0 , key , IV_LENGTH , KEY_LENGTH ) ; return key ; }
target:  Generates a new symmetric encryption key.