A method of securely transferring files from an un-trusted to a trusted network is disclosed. A file that is an archive file of many component files is separated into constituent files. Each file is stored on a first computer connected to an un-trusted network, and a series of initial checks, such as virus, file size, and file extension are performed. If the files pass, the file is transferred to a second server using a one-way file transfer mechanism. A series of secondary checks, similar to the initial checks is performed on each file transferred. For text files or images, a simplified security rule is applied. An open format transform is performed on proprietary format type files, and embedded file components are separated out. A user-definable security rule set is performed on each open format transform component. If all security tests pass, the file is reassembled and transferred to the trusted network.