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|
package oprf
import (
"crypto/rand"
"github.com/cloudflare/circl/group"
"github.com/cloudflare/circl/zk/dleq"
)
type client struct{ params }
type Client struct {
client
}
type VerifiableClient struct {
client
pkS *PublicKey
}
type PartialObliviousClient struct {
client
pkS *PublicKey
}
func (c client) Blind(inputs [][]byte) (*FinalizeData, *EvaluationRequest, error) {
if len(inputs) == 0 {
return nil, nil, ErrInvalidInput
}
blinds := make([]Blind, len(inputs))
for i := range inputs {
blinds[i] = c.params.group.RandomScalar(rand.Reader)
}
return c.blind(inputs, blinds)
}
func (c client) DeterministicBlind(inputs [][]byte, blinds []Blind) (*FinalizeData, *EvaluationRequest, error) {
if len(inputs) == 0 {
return nil, nil, ErrInvalidInput
}
if len(inputs) != len(blinds) {
return nil, nil, ErrInvalidInput
}
return c.blind(inputs, blinds)
}
func (c client) blind(inputs [][]byte, blinds []Blind) (*FinalizeData, *EvaluationRequest, error) {
blindedElements := make([]Blinded, len(inputs))
dst := c.params.getDST(hashToGroupDST)
for i := range inputs {
point := c.params.group.HashToElement(inputs[i], dst)
if point.IsIdentity() {
return nil, nil, ErrInvalidInput
}
blindedElements[i] = c.params.group.NewElement().Mul(point, blinds[i])
}
evalReq := &EvaluationRequest{blindedElements}
finData := &FinalizeData{inputs, blinds, evalReq}
return finData, evalReq, nil
}
func (c client) unblind(serUnblindeds [][]byte, blindeds []group.Element, blind []Blind) (err error) {
invBlind := c.params.group.NewScalar()
U := c.params.group.NewElement()
for i := range blindeds {
invBlind.Inv(blind[i])
U.Mul(blindeds[i], invBlind)
serUnblindeds[i], err = U.MarshalBinaryCompress()
if err != nil {
return err
}
}
return nil
}
func (c client) validate(f *FinalizeData, e *Evaluation) (err error) {
if l := len(f.blinds); len(f.evalReq.Elements) != l || len(e.Elements) != l {
err = ErrInvalidInput
}
return
}
func (c client) finalize(f *FinalizeData, e *Evaluation, info []byte) ([][]byte, error) {
unblindedElements := make([][]byte, len(f.blinds))
err := c.unblind(unblindedElements, e.Elements, f.blinds)
if err != nil {
return nil, err
}
h := c.params.hash.New()
outputs := make([][]byte, len(f.inputs))
for i := range f.inputs {
outputs[i] = c.params.finalizeHash(h, f.inputs[i], info, unblindedElements[i])
}
return outputs, nil
}
func (c Client) Finalize(f *FinalizeData, e *Evaluation) (outputs [][]byte, err error) {
if err = c.validate(f, e); err != nil {
return nil, err
}
return c.client.finalize(f, e, nil)
}
func (c VerifiableClient) Finalize(f *FinalizeData, e *Evaluation) (outputs [][]byte, err error) {
if err := c.validate(f, e); err != nil {
return nil, err
}
if !(dleq.Verifier{Params: c.getDLEQParams()}).VerifyBatch(
c.params.group.Generator(),
c.pkS.e,
f.evalReq.Elements,
e.Elements,
e.Proof,
) {
return nil, ErrInvalidProof
}
return c.client.finalize(f, e, nil)
}
func (c PartialObliviousClient) Finalize(f *FinalizeData, e *Evaluation, info []byte) (outputs [][]byte, err error) {
if err = c.validate(f, e); err != nil {
return nil, err
}
tweakedKey, err := c.pointFromInfo(info)
if err != nil {
return nil, err
}
if !(dleq.Verifier{Params: c.getDLEQParams()}).VerifyBatch(
c.params.group.Generator(),
tweakedKey,
e.Elements,
f.evalReq.Elements,
e.Proof,
) {
return nil, ErrInvalidProof
}
return c.client.finalize(f, e, info)
}
func (c PartialObliviousClient) pointFromInfo(info []byte) (group.Element, error) {
m, err := c.params.scalarFromInfo(info)
if err != nil {
return nil, err
}
T := c.params.group.NewElement().MulGen(m)
tweakedKey := c.params.group.NewElement().Add(T, c.pkS.e)
if tweakedKey.IsIdentity() {
return nil, ErrInvalidInfo
}
return tweakedKey, nil
}
|
