Secure Back Door (SBD) is a tool that provides ultra-secure and minimal access to a computer, which allows you to run a single command based on a one time key. It is good if you don't want to have an SSH server running all the time, and only want to start it when needed. Because it is written in only a few lines of code, it is hoped that it will be less susceptible to security exploits than a program like SSH.
cryptmount is a utility for creating and managing secure filing systems on GNU/Linux systems. After initial setup, it allows any user to mount or unmount filesystems on demand, solely by providing the decryption password, with any system devices needed to access the filing system being configured automatically. A wide variety of encryption schemes (provided by the kernel dm-crypt system and the libgcrypt library) can be used to protect both the filesystem and the access key. The protected filing systems can reside in either ordinary files or disk partitions. The package also supports encrypted swap partitions, and automatic configuration on system boot-up.
OpenVPN Auth Passwd is a plugin that authenticates OpenVPN users using the local passwd or shadow files, using a privilege separation model. The authentication method must be defined in the Makefile prior to the compilation of the plugin. On shadowed systems it uses the functions provided in the shadow suite and, on other systems, the getpwnam(3) function to verify the username/password.