// Split creates PVSS shares encrypted by the public keys in X and
// provides a NIZK encryption consistency proof for each share.
func (pv *PVSS) Split(X []abstract.Point, secret abstract.Scalar) ([]int, []abstract.Point, []ProofCore, []byte, error) {
n := len(X)
// Create secret sharing polynomial
priPoly := new(poly.PriPoly).Pick(pv.suite, pv.t, secret, random.Stream)
// Create secret set of shares
shares := new(poly.PriShares).Split(priPoly, n)
// Create public polynomial commitments with respect to basis H
pubPoly := new(poly.PubPoly).Commit(priPoly, pv.h)
// Prepare data for encryption consistency proofs ...
share := make([]abstract.Scalar, n)
H := make([]abstract.Point, n)
idx := make([]int, n)
for i := range idx {
idx[i] = i
share[i] = shares.Share(i)
H[i] = pv.h
}
// ... and create them
proof, err := NewProof(pv.suite, H, X, nil)
if err != nil {
return nil, nil, nil, nil, err
}
_, sX, err := proof.SetupCollective(share...)
if err != nil {
return nil, nil, nil, nil, err
}
polyBin, err := pubPoly.MarshalBinary()
if err != nil {
return nil, nil, nil, nil, err
}
return idx, sX, proof.Core, polyBin, nil
}
func (lp *LifePolicy) TakeOutPolicy(serverList []abstract.Point,
selectInsurers func([]abstract.Point, int) []abstract.Point,
g abstract.Group, t int, n int) (*LifePolicy, bool) {
// If n is less than the expected number of shares to reconstruct the
// secret, fail
if n < t {
return lp, false
}
// Initialize the policy.
// If we have no selectInsurers function, use the basic algorithm.
if selectInsurers == nil {
selectInsurers = selectInsurersBasic
}
lp.insurersList = selectInsurers(serverList, n)
if lp.insurersList == nil || len(lp.insurersList) < n {
return lp, false
}
//TODO: Use bytes maybe?
lp.proofList = new(list.List)
// Create a new polynomial from the private key where t shares are
// needed to reconstruct the secret. Then, split it into secret shares
// and create the public polynomial.
pripoly := new(poly.PriPoly).Pick(g, t, lp.keyPair.Secret, random.Stream)
prishares := new(poly.PriShares).Split(pripoly, n)
pubPoly := new(poly.PubPoly)
pubPoly.Init(g, n, nil)
pubPoly = new(poly.PubPoly).Commit(pripoly, nil)
// Mark the policy as being in the setup stage and ready to begin
// receiving PolicyApproveMessages.
lp.policyStatus = PolicySetup
// Send each share off to the appropriate server.
for i := 0; i < n; i++ {
requestMsg := new(RequestInsuranceMessage).createMessage(
lp.keyPair.Public, i, prishares.Share(i), pubPoly)
lp.cman.Put(lp.insurersList[i],
new(PolicyMessage).createRIMessage(requestMsg))
}
receivedList := make([]bool, len(lp.insurersList))
// TODO: Add a timeout such that this process will end after a certain
// time and a new batch of insurers can be picked.
// TODO: Make it so that it stops as soon as we get R other insurers
// for t <= r <= n
for lp.proofList.Len() < n {
for i := 0; i < n; i++ {
// If we have already received a certificate for this
// node, move on.
if receivedList[i] == true {
continue
}
msg := new(PolicyMessage)
lp.cman.Get(lp.insurersList[i], msg)
msgType, err := lp.handlePolicyMessage(msg)
// Merely for efficiency, to update the receive list.
if msgType == PolicyApproved {
receivedList[i] = (err == nil)
}
}
}
lp.policyStatus = PolicyReady
return lp, true
}
