cloudflared-mirror/vendor/github.com/marten-seemann/qtls-go1-19/cfkem.go

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// Copyright 2022 Cloudflare, Inc. All rights reserved. Use of this source code
// is governed by a BSD-style license that can be found in the LICENSE file.
//
// Glue to add Circl's (post-quantum) hybrid KEMs.
//
// To enable set CurvePreferences with the desired scheme as the first element:
//
// import (
// "github.com/cloudflare/circl/kem/tls"
// "github.com/cloudflare/circl/kem/hybrid"
//
// [...]
//
// config.CurvePreferences = []tls.CurveID{
// qtls.X25519Kyber512Draft00,
// qtls.X25519,
// qtls.P256,
// }
package qtls
import (
"github.com/cloudflare/circl/kem"
"github.com/cloudflare/circl/kem/hybrid"
"crypto/tls"
"fmt"
"io"
"sync"
"time"
)
// Either ecdheParameters or kem.PrivateKey
type clientKeySharePrivate interface{}
var (
X25519Kyber512Draft00 = CurveID(0xfe30)
X25519Kyber768Draft00 = CurveID(0xfe31)
invalidCurveID = CurveID(0)
)
func kemSchemeKeyToCurveID(s kem.Scheme) CurveID {
switch s.Name() {
case "Kyber512-X25519":
return X25519Kyber512Draft00
case "Kyber768-X25519":
return X25519Kyber768Draft00
default:
return invalidCurveID
}
}
// Extract CurveID from clientKeySharePrivate
func clientKeySharePrivateCurveID(ks clientKeySharePrivate) CurveID {
switch v := ks.(type) {
case kem.PrivateKey:
ret := kemSchemeKeyToCurveID(v.Scheme())
if ret == invalidCurveID {
panic("cfkem: internal error: don't know CurveID for this KEM")
}
return ret
case ecdheParameters:
return v.CurveID()
default:
panic("cfkem: internal error: unknown clientKeySharePrivate")
}
}
// Returns scheme by CurveID if supported by Circl
func curveIdToCirclScheme(id CurveID) kem.Scheme {
switch id {
case X25519Kyber512Draft00:
return hybrid.Kyber512X25519()
case X25519Kyber768Draft00:
return hybrid.Kyber768X25519()
}
return nil
}
// Generate a new shared secret and encapsulates it for the packed
// public key in ppk using randomness from rnd.
func encapsulateForKem(scheme kem.Scheme, rnd io.Reader, ppk []byte) (
ct, ss []byte, alert alert, err error) {
pk, err := scheme.UnmarshalBinaryPublicKey(ppk)
if err != nil {
return nil, nil, alertIllegalParameter, fmt.Errorf("unpack pk: %w", err)
}
seed := make([]byte, scheme.EncapsulationSeedSize())
if _, err := io.ReadFull(rnd, seed); err != nil {
return nil, nil, alertInternalError, fmt.Errorf("random: %w", err)
}
ct, ss, err = scheme.EncapsulateDeterministically(pk, seed)
return ct, ss, alertIllegalParameter, err
}
// Generate a new keypair using randomness from rnd.
func generateKemKeyPair(scheme kem.Scheme, rnd io.Reader) (
kem.PublicKey, kem.PrivateKey, error) {
seed := make([]byte, scheme.SeedSize())
if _, err := io.ReadFull(rnd, seed); err != nil {
return nil, nil, err
}
pk, sk := scheme.DeriveKeyPair(seed)
return pk, sk, nil
}
// Events. We cannot use the same approach as used in our plain Go fork
// as we cannot change tls.Config, tls.ConnectionState, etc. Also we do
// not want to maintain a fork of quic-go itself as well. This seems
// the simplest option.
// CFEvent. There are two events: one emitted on HRR and one emitted
type CFEvent interface {
// Common to all events
ServerSide() bool // true if server-side; false if on client-side
// HRR event. Emitted when an HRR happened.
IsHRR() bool // true if this is an HRR event
// Handshake event.
IsHandshake() bool // true if this is a handshake event.
Duration() time.Duration // how long did the handshake take?
KEX() tls.CurveID // which kex was established?
}
type CFEventHandler func(CFEvent)
// Registers a handler to be called when a CFEvent is emitted; returns
// the previous handler.
func SetCFEventHandler(handler CFEventHandler) CFEventHandler {
cfEventMux.Lock()
ret := cfEventHandler
cfEventHandler = handler
cfEventMux.Unlock()
return ret
}
func raiseCFEvent(ev CFEvent) {
cfEventMux.Lock()
handler := cfEventHandler
cfEventMux.Unlock()
if handler != nil {
handler(ev)
}
}
var (
cfEventMux sync.Mutex
cfEventHandler CFEventHandler
)
type cfEventHRR struct{ serverSide bool }
func (*cfEventHRR) IsHRR() bool { return true }
func (ev *cfEventHRR) ServerSide() bool { return ev.serverSide }
func (*cfEventHRR) IsHandshake() bool { return false }
func (ev *cfEventHRR) Duration() time.Duration { panic("wrong event") }
func (ev *cfEventHRR) KEX() tls.CurveID { panic("wrong event") }
type cfEventHandshake struct {
serverSide bool
duration time.Duration
kex tls.CurveID
}
func (*cfEventHandshake) IsHRR() bool { return false }
func (ev *cfEventHandshake) ServerSide() bool { return ev.serverSide }
func (*cfEventHandshake) IsHandshake() bool { return true }
func (ev *cfEventHandshake) Duration() time.Duration { return ev.duration }
func (ev *cfEventHandshake) KEX() tls.CurveID { return ev.kex }