Usage

Let's create an election where people with the Estonian id numbers 47101010033 and 36603150241 can vote.

mkdir -p ../myelection
cp -t ../myelection *.go *.py
cd ../myelection
echo 47101010033 36603150241 | python2 eligiblevoters.py # downloads id card public keys from sk.ee

# look below for instructions on how to generate a certificate
go run reg-server.go ../SECRET.pem # leave it running and let the people register

go run prepare.go ../SECRET.pem 24h "my election"
# the time limit for election duration is approximate, overestimating doesn't hurt
# the preparation includes bulk RSA signing and will take a while

go run vote-server.go ../SECRET.pem # and wait for people to vote

go run count-votes.go

Directory structure

Every election lives in its own directory. Do not store anything private in the election directory, it is intended to be published together with the election results.

Its initial contents:

• voters/%{id}x.cer - x509 certificats of eligible voters, in DER binary format
• *.go *.py - the code used to run the election

The registration server fills in

• voters/%{id}x.pk - LSAGS public key
• voters/%{id}x.sig - Voters's signature on that public key
• voters/%{id}x.cargo - Voter's storage, for encrypted LSAGS secret key.
• voters/%{id}x.reg - Registration transcript (not used).

The prepare script creates

• groups/groups - Lists of groups' members
• groups/%{gid}.cargos - Cargos of everyone in this group
• groups/%{gid}.pks - Public keys of everyone in this group
• A corresponding .sig file for each of these, containing the server signature for it

The voting server creates the following files:

• votes/%{gid}s/%{y_tilde}x.vote - The votes

Certificates

Generate a self-signed x509 certificate with a RSA keypair (the cert.pem is compatible with voteclient):

openssl req -x509 -newkey rsa:2048 -keyout ../secretcert.pem -out cert.pem -days 5 -nodes

Get a plain RSA secret key for the election servers:

openssl rsa -in ../secretcert.pem -out ../SECRET.pem

Get a plain RSA public key for use with openssl dgst tool (for manual verification):

openssl x509 -pubkey -noout -in cert.pem PUBLIC.pem

File formats

The common header

All files signed by the server have the following header:

                    1               2                (64-bit words)
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7  (8-bit bytes)
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 0 | FILE TYPE TAG |  START TIME   |   END TIME    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 3 |        ELECTION NAME          |   GROUP ID*   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-?-?-?-?-?-?-?-?

The group id field is not present in the common groups file.

Specific formats

All integers are little endian and 8 bytes long unless otherwise noted (some are 2 bytes long).

client->server	Registration request (No header at all)
REGISTER	file type tag
uint64	voter id
byte	signature algorithm id (0x03 = RSASHA1 for now)
uint16	sig_size
[sig_size]byte	ID card signature on the LSAGS public key
[29]byte	LSAGS public key
[]byte	Everything else is opaque cargo

groups, GROUPSLL	Groups' members lists (No group number in header)
uint64	n - number of members in group 0
[n]uint64	members' voter id numbers
...	... (same for next group)

%{gid}.pks, GROUPPKS	Public keys of members of group with id gid
[][29]byte	Public keys, 29 bytes each

%{gid}.cargos, GROUPCGS	Cargos of members of group with id gid
uint64	voter id of the owner of the cargo
uint16	size - size of the cargo
[size]byte	the cargo
...	... (same for next voter)

%{y_tilde}x.cargos, VOTEVOTE	A vote (the header is not transmitted, but is signed)
uint16	size - size of the vote (message)
[size]byte	the vote