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. Therefore, a Rubberhose disk can only be safely written to after all the passphrases have been entered. Everything 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.

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