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// Package sumvec is a VDAF for aggregating vectors of integers in a pre-determined range.
package sumvec
import (
"errors"
"github.com/cloudflare/circl/vdaf/prio3/arith"
"github.com/cloudflare/circl/vdaf/prio3/arith/fp128"
"github.com/cloudflare/circl/vdaf/prio3/internal/cursor"
"github.com/cloudflare/circl/vdaf/prio3/internal/flp"
"github.com/cloudflare/circl/vdaf/prio3/internal/prio3"
)
type (
poly = fp128.Poly
Vec = fp128.Vec
Fp = fp128.Fp
AggShare = prio3.AggShare[Vec, Fp]
InputShare = prio3.InputShare[Vec, Fp]
Nonce = prio3.Nonce
OutShare = prio3.OutShare[Vec, Fp]
PrepMessage = prio3.PrepMessage
PrepShare = prio3.PrepShare[Vec, Fp]
PrepState = prio3.PrepState[Vec, Fp]
PublicShare = prio3.PublicShare
VerifyKey = prio3.VerifyKey
)
// SumVec is a verifiable distributed aggregation function in which each
// measurement is a fixed-length vector of integers in the range [0, 2^bits).
// the aggregated result is the sum of all the vectors.
type SumVec struct {
p prio3.Prio3[[]uint64, []uint64, *flpSumVec, Vec, Fp, *Fp]
}
func New(numShares uint8, length, bits, chunkLength uint, context []byte) (s *SumVec, err error) {
const sumVecID = 3
flp, err := newFlpSumVec(length, bits, chunkLength)
if err != nil {
return nil, err
}
s = new(SumVec)
s.p, err = prio3.New(flp, sumVecID, numShares, context)
if err != nil {
return nil, err
}
return s, nil
}
func (s *SumVec) Params() prio3.Params { return s.p.Params() }
func (s *SumVec) Shard(measurement []uint64, nonce *Nonce, rand []byte,
) (PublicShare, []InputShare, error) {
return s.p.Shard(measurement, nonce, rand)
}
func (s *SumVec) PrepInit(
verifyKey *VerifyKey,
nonce *Nonce,
aggID uint8,
publicShare PublicShare,
inputShare InputShare,
) (*PrepState, *PrepShare, error) {
return s.p.PrepInit(verifyKey, nonce, aggID, publicShare, inputShare)
}
func (s *SumVec) PrepSharesToPrep(prepShares []PrepShare) (*PrepMessage, error) {
return s.p.PrepSharesToPrep(prepShares)
}
func (s *SumVec) PrepNext(state *PrepState, msg *PrepMessage) (*OutShare, error) {
return s.p.PrepNext(state, msg)
}
func (s *SumVec) AggregateInit() AggShare { return s.p.AggregateInit() }
func (s *SumVec) AggregateUpdate(aggShare *AggShare, outShare *OutShare) {
s.p.AggregateUpdate(aggShare, outShare)
}
func (s *SumVec) Unshard(aggShares []AggShare, numMeas uint) (aggregate *[]uint64, err error) {
return s.p.Unshard(aggShares, numMeas)
}
type flpSumVec struct {
flp.FLP[flp.GadgetParallelSumInnerMul, poly, Vec, Fp, *Fp]
length uint
bits uint
chunkLen uint
}
func newFlpSumVec(length, bits, chunkLen uint) (*flpSumVec, error) {
if bits > 64 {
return nil, ErrBits
}
numGadgetCalls := (length*bits + chunkLen - 1) / chunkLen
s := new(flpSumVec)
s.length = length
s.bits = bits
s.chunkLen = chunkLen
s.Valid.MeasurementLen = length * bits
s.Valid.JointRandLen = numGadgetCalls
s.Valid.OutputLen = length
s.Valid.EvalOutputLen = 1
s.Gadget = flp.GadgetParallelSumInnerMul{Count: chunkLen}
s.NumGadgetCalls = numGadgetCalls
s.FLP.Eval = s.Eval
return s, nil
}
func (s *flpSumVec) Eval(
out Vec, g flp.Gadget[poly, Vec, Fp, *Fp], numCalls uint,
meas, jointRand Vec, numShares uint8,
) {
var invShares Fp
invShares.InvUint64(uint64(numShares))
out[0] = flp.RangeCheck(g, numCalls, s.chunkLen, &invShares, meas, jointRand)
}
func (s *flpSumVec) Encode(measurement []uint64) (out Vec, err error) {
if len(measurement) != int(s.length) {
return nil, flp.ErrMeasurementLen
}
out = make(Vec, s.Valid.MeasurementLen)
outCur := cursor.New(out)
for i := range measurement {
err = outCur.Next(s.bits).SplitBits(measurement[i])
if err != nil {
return nil, err
}
}
return
}
func (s *flpSumVec) Truncate(meas Vec) (out Vec) {
out = arith.NewVec[Vec](s.length)
measCur := cursor.New(meas)
for i := range out {
out[i] = measCur.Next(s.bits).JoinBits()
}
return
}
func (s *flpSumVec) Decode(output Vec, numMeas uint) (*[]uint64, error) {
if len(output) < int(s.Valid.OutputLen) {
return nil, flp.ErrOutputLen
}
var err error
out := make([]uint64, len(output))
for i := range output {
out[i], err = output[i].GetUint64()
if err != nil {
return nil, err
}
}
return &out, nil
}
var ErrBits = errors.New("bits larger than 64 is not supported")
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