## Migration Guide of Faster ECDSA Keygen

1. faster ecdsa keygen needs an out channel with more capacity, for one party the out channel capacity should be 2. (for paillier key negotiation and ecdsa keygen are parallelized)

2. faster ecdsa keygen needs handle twice output from end channel. one is for ecdsa keygen results, another is for paillier key negotiation results. Both are in ecdsa keygen.LocalPartySaveData scheme, with some fields empty.

3. so once ecdsa keygen done, we can tell user the key has been generated. (in 1 second)

4. once paillier key negotiation done, we can let user do further rounds. (in 20 seconds)

### example
#### Channel Make

errCh := make(chan *tss.Error, len(pIDs))
outCh := make(chan tss.Message, 2*len(pIDs))
endCh := make(chan keygen.LocalPartySaveData, len(pIDs))

#### NewLocalParty

NewLocalParty(params, outCh, endCh)

#### Accept Results

case save := <-endCh:
    // SAVE a test fixture file for this P (if it doesn't already exist)
    // .. here comes a workaround to recover this party's index (it was removed from save data)
    index, err := save.OriginalIndex()
    assert.NoErrorf(t, err, "should not be an error getting a party's index from save data")
    tryWriteTestFixtureFile(t, index, save)

    atomic.AddInt32(&ended, 1)
    if atomic.LoadInt32(&ended) == int32(len(pIDs))*2 {
        t.Logf("Done. Received save data from %d participants", ended)
        break keygen
    }


func tryWriteTestFixtureFile(t *testing.T, index int, data keygen.LocalPartySaveData) {
	fixtureFileName := makeTestFixtureFilePath(index)

	dir := path.Dir(fixtureFileName)
	err := os.MkdirAll(dir, 0751)
	assert.NoError(t, err)
	// fixture file does not already exist?
	// if it does, we won't re-create it here
	fi, err := os.Stat(fixtureFileName)
	if !(err == nil && fi != nil && !fi.IsDir()) {
		fd, err := os.OpenFile(fixtureFileName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
		if err != nil {
			assert.NoErrorf(t, err, "unable to open fixture file %s for writing", fixtureFileName)
		}
		bz, err := json.Marshal(&data)
		if err != nil {
			t.Fatalf("unable to marshal save data for fixture file %s", fixtureFileName)
		}
		_, err = fd.Write(bz)
		if err != nil {
			t.Fatalf("unable to write to fixture file %s", fixtureFileName)
		}
		t.Logf("Saved a test fixture file for party %d: %s", index, fixtureFileName)
	} else {
		if err != nil {
			assert.NoErrorf(t, err, "unable to open fixture file %s for writing", fixtureFileName)
		}
		bz, err := ioutil.ReadFile(fixtureFileName)
		if err != nil {
			assert.NoErrorf(t, err, "unable to open read file all %s", fixtureFileName)
		}
		var inObj keygen.LocalPartySaveData
		if err = json.Unmarshal(bz, &inObj); err != nil {
			assert.NoErrorf(t, err, "unable to unmaarshal json %s", fixtureFileName)
		}
		for _, kbxj := range inObj.BigXj {
			if kbxj != nil {
				kbxj.SetCurve(tss.S256())
			}
		}
		if inObj.ECDSAPub != nil {
			inObj.ECDSAPub.SetCurve(tss.S256())
		}
		// if no paillier keys
		if inObj.NTildej == nil || inObj.NTildej[0] == nil {
			inObj.NTildej = data.NTildej
			inObj.H1j = data.H1j
			inObj.H2j = data.H2j
			inObj.PaillierPKs = data.PaillierPKs
			inObj.LocalPreParams = data.LocalPreParams
			fmt.Println("patched pallier")
		}

		// if no xi
		if inObj.Xi == nil {
			inObj.Xi = data.Xi
			inObj.ShareID = data.ShareID
			fmt.Println("patched Xi")
		}

		t.Logf("Fixture file already exists for party %d; try scanning any attributes to add: %s", index, fixtureFileName)
		fd, err := os.OpenFile(fixtureFileName, os.O_CREATE|os.O_TRUNC|os.O_RDWR, 0600)
		bzs, err := json.Marshal(inObj)
		_, err = fd.Write(bzs)
		if err != nil {
			t.Fatalf("unable to write to fixture file %s", fixtureFileName)
		}
		t.Logf("Saved a test fixture file for party %d: %s", index, fixtureFileName)
	}
}

### Compatibility Change
If not all parties update, `RejectionSampleVersion` needs to be controlled.

func NewParameters(ec elliptic.Curve, ctx *PeerContext, partyID *PartyID, partyCount, threshold int, 
                   needsIdentification bool, nonce int,
                   opts ...ConfigOpt) *Parameters { ... }


func WithRejectionSampleVersion(version RejectionSampleVersion) ConfigOpt {
	return func(config *Config) error {
		config.VersionInfo = NewVersion(WithRejectionSample(version))
		return nil
	}
}

func WithSafePrimeGenTimeout(duration time.Duration) ConfigOpt {
	return func(config *Config) error {
		config.SafePrimeTimeout = duration
		return nil
	}
}

// usage 
params := tss.NewParameters(tss.EC(), p2pCtx, pIDs[0], len(pIDs), threshold, false, 0, 
                            tss.WithRejectionSampleVersion(tss.RejectionSampleV1), 
                            tss.WithSafePrimeGenTimeout(time.Millisecond*1000))

### Log Changes
`universal-keygen` keygen name for universal including xi and Paillier key setup
`frost-keygen` keygen name for xi
`WARN: unrecognised message ignored` expected log