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join.go
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join.go
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package ecdaa
import (
"crypto/x509"
"encoding/binary"
"fmt"
"github.com/akakou-fork/amcl-go/miracl/core"
"github.com/akakou-fork/amcl-go/miracl/core/FP256BN"
amcl_utils "github.com/akakou/fp256bn-amcl-utils"
"github.com/akakou/ecdaa/tpm_utils"
)
type JoinSeed struct {
Basename []byte
S2 []byte
Y2 *FP256BN.BIG
}
func GenJoinSeed(rng *core.RAND) (*JoinSeed, *FP256BN.ECP, error) {
var seed JoinSeed
basename := amcl_utils.RandomBytes(rng, 32)
hash := amcl_utils.NewHash()
hash.WriteBytes(basename)
B, i, err := hash.HashToECP()
if err != nil {
return nil, nil, err
}
numBuf := make([]byte, binary.MaxVarintLen32)
binary.PutVarint(numBuf, int64(i))
s2Buf := append(numBuf, basename[:]...)
seed.Basename = basename[:]
seed.S2 = s2Buf
seed.Y2 = B.GetY()
return &seed, B, nil
}
type JoinRequest struct {
Proof *SchnorrProof
Q *FP256BN.ECP
}
type JoinRequestTPM struct {
JoinReq *JoinRequest
EKCert *x509.Certificate
SrkName []byte
}
/**
* Step2. generate request for join (by Member)
*/
func GenJoinReq(seed *JoinSeed, rng *core.RAND) (*JoinRequest, *FP256BN.BIG, error) {
/* create key and get public key */
sk := amcl_utils.RandomBig(rng)
/* set zero buffers to P1 */
hash := amcl_utils.NewHash()
hash.WriteBytes(seed.S2)
bX := hash.SumToBIG()
B := FP256BN.NewECPbigs(bX, seed.Y2)
// get result (Q)
Q := B.Mul(sk)
proof := proveSchnorr([]byte(""), nil, sk, B, Q, rng)
req := JoinRequest{
proof,
Q,
}
return &req, sk, nil
}
func GenJoinReqWithTPM(seed *JoinSeed, tpm *tpm_utils.TPM, rng *core.RAND) (*JoinRequestTPM, *KeyHandles, error) {
/* create key and get public key */
handle, ekHandle, srkHandle, _, err := tpm.CreateKey()
if err != nil {
return nil, nil, err
}
hash := amcl_utils.NewHash()
hash.WriteBytes(seed.S2)
bX := hash.SumToBIG()
B := FP256BN.NewECPbigs(bX, seed.Y2)
/* run commit and get U1 */
comRsp, E, _, K, err := (*tpm).Commit(handle, B, seed.S2, B)
if err != nil {
return nil, nil, fmt.Errorf("commit error: %v", err)
}
/* calc hash c2 = H( U1 | P1 | Q | m ) */
hash = amcl_utils.NewHash()
hash.WriteECP(E, B, K)
c2 := hash.SumToBIG()
/* sign and get s1, n */
c2Buf := amcl_utils.BigToBytes(c2)
_, s1, n, err := (*tpm).Sign(c2Buf[:], comRsp.Counter, handle)
if err != nil {
return nil, nil, fmt.Errorf("sign error: %v", err)
}
/* calc hash c1 = H( n | c2 ) */
hash = amcl_utils.NewHash()
hash.WriteBIG(n)
hash.WriteBytes(c2Buf[:])
c1 := hash.SumToBIG()
EKCert, err := (*tpm).ReadEKCert()
if err != nil {
return nil, nil, fmt.Errorf("sign error: %v", err)
}
proof := SchnorrProof{
SmallC: c1,
SmallN: n,
SmallS: s1,
}
req := JoinRequest{
Proof: &proof,
Q: K,
}
reqTPM := JoinRequestTPM{
EKCert: EKCert,
JoinReq: &req,
SrkName: srkHandle.Name.Buffer,
}
keyHandles := KeyHandles{
EkHandle: ekHandle,
SrkHandle: srkHandle,
Handle: handle,
}
return &reqTPM, &keyHandles, nil
}
func VerifyJoinReq(req *JoinRequest, seed *JoinSeed, B *FP256BN.ECP) error {
err := verifySchnorr([]byte(""), nil, req.Proof, B, req.Q)
return err
}