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[rubberhose also acts as strong conventional crypto file-system]

RUBBERHOSE review by Steven Baum

   Rubberhose is a deniable cryptography package that lets someone not
   wanting to disclose plaintext data corresponding to their encrypted data
   show that there is more than one interpretation of the latter.

   Rubberhose works by initially writing random characters to an entire hard
   drive or other dynamic storage device. This random noise is
   indistinguishable from the encrypted data to be stored on that disk. If
   you have a 1 GB drive and want to have two Rubberhose encrypted portions
   of 400 MB and 200 MB, it assumes that each aspect (as the encrypted
   partitions are called) will be 1 GB and fill the entire drive. It will
   keep doing this until the drive is really filled to capacity with
   encrypted material. It breaks up the pieces of each aspect into small
   pieces and scatters them across the entire 1 GB drive in a random manner,
   with each aspect looking as if it is actually 1 GB in size upon
   decryption.

   Each aspect has its own passphrase that must be separately decrypted, and
   if a hard drive is seized neither mathematical analysis nor physical disk
   testing can reveal how many aspects actually exist. Internal maps are used
   to locate where the data is stored amongst the random characters, with
   each aspect having its own map which can only be decrypted via its
   specific passphrase. As such, a Rubberhose disk only be written to after
   all the passphrases have been entered. Everything is works on a "need to
   know" basis, i.e. each aspect knows nothing about the others other than
   when to avoid writing over the top of another.

   Other features of Rubberhose include:
     * a choice of cryptographic algorithms including DES, 3DES, IDEA, RC5,
       Blowfish, Twofish and CAST;
     * compatibility with several filesystems including UFS, ext2fs, FAT and
       FAT32;
     * time-based passphrases, e.g. configuring it to demand re-entry of a
       passphrase after a given amount of time or to lock out users after a
       specified amount of idle time;
     * anti-passphrase-cracking features, e.g. an internally generated
       passphrase is generated upon the creation of each new aspect that is
       encrypted with the user passphrase for that aspect;
     * a design ensuring that if one block of data in an aspect is decrypted,
       then it cannot be used to decrypt the remaining blocks;
     * frequent block-swapping to confound disk surface analysis based on the
       intensity of block use and contiguous block prediction; and
     * "whitening code," i.e. code for the prevention of plaintext attacks
       that perturbs the encryption process in a non-predictable way such
       that some bits in an encrypted block are flipped and some aren't.
   One can't help but admire the motives as well as the skill of those who
   designed and built this package:

     Rubberhose was originally conceived by crypto-programmer Julian Assange
     as a tool for human rights workers who needed to protect sensitive data
     in the field, particularly lists of activists and details of incidents
     of abuse. Repressive regimes in places like East Timor, Russia, Kosovo,
     Guatemala, Iraq, Sudan and The Congo conduct human rights abuses
     regularly. Our team has met with human rights groups and heard
     first-hand accounts of such abuses. Human rights workers carry vital
     data on laptops through the most dangerous situations, sometimes being
     stopped by military patrols who would have no hesitation in torturing a
     suspect until he or she revealed a passphrase to unlock the data. We
     want to help these sorts of campaigners, particularly the brave people
     in the field who risk so much to smuggle data about the abuses out to
     the rest of the world.