<s.sriniva...@surrey.ac.uk> writes:

Dear Sriram,

I'm CCing this reply to the VIFF mailing list, where the other VIFF
developers are also subscribed. I'm handing in my dissertation this
week, so you should not only discuss things with me :-)

> I hope this mail finds you in great spirits. My name is Sriram and I
> am currently a researcher with the Trustworthy Voting Systems group at
> the University of Surrey. I recently completed my PhD from Royal
> Holloway working under Prof. Kenny Paterson. My area of work of
> Identity Based Cryptography.
> I have just come across VIFF today and managed to get a few examples
> to work on my computer after a few glitches. I am a newbie to Multi
> Party Computation, but I was excited by what VIFF could do.

Great that you made it work!

> I am writing with a few queries and I will be grateful for any help.
> As part of our project, we have implemented an early prototype of an
> electronic voting scheme which has been called Pret a Voter in the
> literature. The vote casting is paper based and the voter tears the
> ballot in half and shreds the left half of the ballot which has a
> randomized candidate list and submits the right hand side to a scanner
> that reads the vote and an encrypted barcode that eventually enables
> recovery of the vote. Basically, the idea is to ensure that the device
> to which the vote is submitted has no information about the vote. This
> is front end.
> The back end where tallying is done is currently based on mixnets but
> we are hoping to develop a new version that uses Homomorphic
> Encryption so that we can handle different kinds of (ranked)
> elections. We have currently managed to implement (in java) the
> Paillier cryptosystem as well as the Generalized Paillier
> cryptosystem. Mads Jurik has very kindly given us an implementation of
> the threshold version of the Generalized Paillier Cryptosystem, with a
> trusted dealer.
> One of the ultimate aims of the project is to be able to do
> homomorphic encryption without a trusted dealer. As a first step, this
> means being able to generate an RSA modulus without a trusted dealer.
> From the documentation, I noticed that it was mentioned that
> Distributed RSA has in fact been implemented on VIFF. Please forgive
> me for firing off an e-mail without thorough investigation, but am I
> right that the source code for this is not included in the current
> VIFF release? Would it be possible to obtain the code for this please?

Yes, the code is available from the original author, via his university.
I've now added links to


pointing you to


Thanks for the reminder :-)

> My second question is whether Distributed versions of Paillier (or
> Generalized Paiilier) have been implemented or if there is any plans
> to do so in the near future. I noticed there is a Paillier Module, but
> I understand this is used as a basis to implement other functionality
> - key generation and decryption are not done in a Threshold fashion
> currently.

Right, the viff.paillier module just implements the good old Paillier
cryptosystem, without any threshold support.

> I will be grateful for any help/pointers from you. VIFF looks really
> exciting and I am hoping to spend more time on it and use it in our
> project.
> Best Wishes
> Sriram
> p.s.
> The installation of VIFF was quite complex in that things seemed to
> not work quite right with the newest versions of the various required
> components. I dug out the older versions (I am working with Python 2.4
> and compatible versions of PyOpenSSL, Twisted etc. for 2.4). It may be
> nice in a future release to package everything together if possible.

Which platform are you on? I'm running VIFF on Debian unstable with
Python 2.5.4 and Twisted 9.0 (these are the system packages).

You are certainly right that the initial installation is daunting when
done manually. We could make it easier by bundling things, but nobody
has stepped up to do it.

Martin Geisler

VIFF (Virtual Ideal Functionality Framework) brings easy and efficient
SMPC (Secure Multiparty Computation) to Python. See: http://viff.dk/.

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