TOPIC:

public boolean EncryptAs( String dst, String upswd, String opswd, int perm, int method, byte[] id )

dst - path to save, same as path parameter of SaveAs.
upswd - user password, can be null.
opswd - owner password, can be null.
perm - permission to set, same as GetPermission() method.
       bit 1-2 reserved
       bit 3(0x4) print
       bit 4(0x8) modify
       bit 5(0x10) extract text or image
       others: see PDF reference
method - reserved, currently only AES with V=4 and R=4 mode can be working.
id - must be 32 bytes for file ID. it is divided to 2 array in native library, as each 16 bytes.