Import cloudflare tls

transport/cloudflaretls/cfkem.go

@@ -0,0 +1,104 @@
+// 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{
+//      hybrid.X25519Kyber512Draft00().(tls.TLSScheme).TLSCurveID(),
+//      tls.X25519,
+//      tls.P256,
+//   }
+
+package tls
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/cloudflare/circl/kem"
+	"github.com/cloudflare/circl/kem/hybrid"
+)
+
+// 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
+}