// Get signature from Voter List Server to prove our public key is valid
func GetKeySig(key []byte) ([]byte, error) {
// connect
conn, err := net.Dial("tcp", "localhost"+msg.Service)
if err != nil {
return nil, err
}
// send request
err = msg.WriteBlock(conn, msg.KeySignatureRequest, key)
if err != nil {
return nil, err
}
// Read response
t, err := msg.ReadType(conn)
if err != nil {
return nil, err
}
if t != msg.KeySignatureResponse {
return nil, fmt.Errorf("KeySignatureResponse: invalid response type %d. Expected: %d", t, msg.KeySignatureResponse)
}
sig, err := msg.ReadBlock(conn, maxLength)
conn.Close()
// TODO check sig is valid
return sig, err
}
func SendBlock(messageType msg.Type, data []byte, c net.Conn) {
err := msg.WriteBlock(c, messageType, data)
if err != nil {
fmt.Println("failed to send block:", err)
ConnectionError(c)
return
}
}
func SubmitBallot(ballot, sig []byte) (*msgs.VoteResponse, error) {
fmt.Printf("Casting Ballot: %s\n", ballot)
conn, err := net.Dial("tcp", "localhost"+msg.Service)
if err != nil {
return nil, err
}
var vote msgs.Vote
vote.Ballot = ballot
vote.BallotSignature = sig
// redundant sanity check signature
err = msg.ValidateVote(ballotKey, &vote)
if err != nil {
return nil, err
}
data, err := proto.Marshal(&vote)
if err != nil {
return nil, err
}
err = msg.WriteBlock(conn, msg.Vote, data)
if err != nil {
return nil, err
}
t, err := msg.ReadType(conn)
if err != nil {
return nil, err
}
if t != msg.VoteResponse {
return nil, fmt.Errorf("invalid response type")
}
data, err = msg.ReadBlock(conn, maxLength)
conn.Close()
if err != nil {
return nil, err
}
var response msgs.VoteResponse
err = proto.Unmarshal(data, &response)
if err != nil {
fmt.Println("error reading VoteResponse:", err)
return nil, err
}
b := response.BallotEntry
s := response.BallotEntrySignature
if !sign.CheckSig(voteKey, b, s) {
err = fmt.Errorf("illegal vote response from server. Signature in BallotEntry is invalid")
return nil, err
}
fmt.Printf("Got signed BallotEntry for: %s\n", ballot)
return &response, nil
}
// Get signature for the ballot from ballot server
func GetBallotSig(voterKey *rsa.PrivateKey, keySig, ballot []byte) ([]byte, error) {
conn, err := net.Dial("tcp", "localhost"+msg.Service)
if err != nil {
panic(err)
}
var r msgs.SignatureRequest
// TODO real values
r.VoterPublicKey = keys.PackKey(&voterKey.PublicKey)
blindedBallot, unblinder := sign.Blind(ballotKey, ballot)
r.BlindedBallot = blindedBallot
r.KeySignature = keySig
voterSignature, err := sign.Sign(voterKey, blindedBallot)
if err != nil {
fmt.Println(err)
panic(err)
}
r.VoterSignature = voterSignature
data, err := proto.Marshal(&r)
if err != nil {
panic(err)
}
err = msg.WriteBlock(conn, msg.SignatureRequest, data)
if err != nil {
panic(err)
}
t, err := msg.ReadType(conn)
if err != nil {
panic(err)
}
if t != msg.SignatureResponse {
return nil, fmt.Errorf("SignatureResponse: invalid response type %d. Expected: %d", t, msg.SignatureResponse)
}
data, err = msg.ReadBlock(conn, maxLength)
conn.Close()
if err != nil {
panic(err)
}
var response msgs.SignatureResponse
err = proto.Unmarshal(data, &response)
if err != nil {
fmt.Println("error reading SignatureResponse:", err)
panic(err)
}
if !KeysEqual(r.VoterPublicKey, response.Request.VoterPublicKey) {
fmt.Println("illegal response from server. Voter keys must match:")
fmt.Println(r.VoterPublicKey)
fmt.Println(response.Request.VoterPublicKey)
panic(err)
}
err = msg.ValidateSignatureRequest(response.Request)
if err != nil {
panic(err)
}
newBlindedBallot := response.Request.BlindedBallot
if !bytes.Equal(r.BlindedBallot, newBlindedBallot) {
fmt.Println("Server has proof you voted before!")
// TODO should store ballots (and blinding factors?) from all attempts
// so can try and cast old ballot
panic(err)
}
if !sign.CheckBlindSig(ballotKey, newBlindedBallot, response.BlindedBallotSignature) {
fmt.Println("illegal response from server. Signature in response is invalid:", ballotKey, newBlindedBallot, response.BlindedBallotSignature)
panic(err)
}
sig := sign.Unblind(ballotKey, response.BlindedBallotSignature, unblinder)
return sig, nil
}