Re:Mega, the new MegaUpload, to launch on January 19
by karamazov on Thursday January 17, 2013 @12:04PM
(#5073641)
Homomorphic encryption allows you to encrypt the data and then operate on it. It doesn't (necessarily) imply that each plaintext has exactly one encrypted version. [1]
It's also highly experimental at this point, from what I remember.
[1] As a trivial example, let's say you give me a very large number, and your encryption scheme is to add some number, n, of zero bits at the end. Only you know how many bits you're adding - n is your private key. Regardless of what you pick for n, I can multiply your number by 2 (i.e. bit-shift it) and give the result back to you, which you would then be able to decrypt to the result of the calculation.
This works for any value of n, so I can't tell if two original numbers are the same by inspecting the ciphertexts.
It's also highly experimental at this point, from what I remember.
[1] As a trivial example, let's say you give me a very large number, and your encryption scheme is to add some number, n, of zero bits at the end. Only you know how many bits you're adding - n is your private key. Regardless of what you pick for n, I can multiply your number by 2 (i.e. bit-shift it) and give the result back to you, which you would then be able to decrypt to the result of the calculation.
This works for any value of n, so I can't tell if two original numbers are the same by inspecting the ciphertexts.