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package bidder
import (
"crypto/ed25519"
"fmt"
"kesim.org/seal"
. "kesim.org/seal/nizk"
"kesim.org/seal/nizk/commit"
)
type bid struct {
id ed25519.PrivateKey
ID ed25519.PublicKey
price uint64 // bigendian encoding of the bid
n uint8 // number of bits encoded in zbid.
// bits are derived from zbid and the zero element in
// the slice corresponds to the highest bit in zbid
bits []*commit.Statement
}
// NewBid creates a new Bidder for the given price, using the lower bits up to bitlength
func newBid(price uint64, bitlength uint8) (seal.Bidder, error) {
if bitlength > 63 {
return nil, fmt.Errorf("bitlength too large, maximum is 63")
} else if 0 != (price >> bitlength) {
return nil, fmt.Errorf("price %d too large for given bitlength %d", price, bitlength)
}
var (
e error
bid = &bid{
price: price,
}
)
bid.ID, bid.id, e = ed25519.GenerateKey(nil)
if e != nil {
return nil, e
}
bid.bits = make([]*commit.Statement, bitlength)
for i := bitlength; i > 0; i-- {
set := (price>>(i-1)&1 != 0)
a, b := Curve.RandomScalar(), Curve.RandomScalar()
bid.bits[i-1] = commit.NewStatement(a, b, set)
}
return bid, nil
}
// Commit returns the public commitment to the bits and a signature
// TODO: return signature over bid
func (bid *bid) Commit() (c []*commit.Commitment, pub ed25519.PublicKey, sig []byte) {
c = make([]*commit.Commitment, len(bid.bits))
for i := range bid.bits {
c[i] = bid.bits[i].Commit()
}
return c, bid.ID, nil
}
func (bid *bid) Result() {
}
func (bid *bid) Send(msg []byte, sig []byte) {
}
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