ssl/test/runner/hpke/hpke.go - boringssl - Git at Google

 // Copyright (c) 2020, Google Inc.
 //
 // Permission to use, copy, modify, and/or distribute this software for any
 // purpose with or without fee is hereby granted, provided that the above
 // copyright notice and this permission notice appear in all copies.
 //
 // THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 // WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 // MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 // SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 // WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 // OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 // Package hpke implements Hybrid Public Key Encryption (HPKE).
 //
 // See https://tools.ietf.org/html/draft-irtf-cfrg-hpke-12.
 package hpke

 import (
 	"crypto"
 	"crypto/aes"
 	"crypto/cipher"
 	"encoding/binary"
 	"errors"
 	"fmt"

 	"golang.org/x/crypto/chacha20poly1305"
 )

 // KEM scheme IDs.
 const (
 	P256WithHKDFSHA256   uint16 = 0x0010
 	X25519WithHKDFSHA256 uint16 = 0x0020
 )

 // HPKE AEAD IDs.
 const (
 	AES128GCM        uint16 = 0x0001
 	AES256GCM        uint16 = 0x0002
 	ChaCha20Poly1305 uint16 = 0x0003
 )

 // HPKE KDF IDs.
 const (
 	HKDFSHA256 uint16 = 0x0001
 	HKDFSHA384 uint16 = 0x0002
 	HKDFSHA512 uint16 = 0x0003
 )

 // Internal constants.
 const (
 	hpkeModeBase uint8 = 0
 	hpkeModePSK  uint8 = 1
 )

 // GetHKDFHash returns the crypto.Hash that corresponds to kdf. If kdf is not
 // one the supported KDF IDs, returns an error.
 func GetHKDFHash(kdf uint16) (crypto.Hash, error) {
 	switch kdf {
 	case HKDFSHA256:
 		return crypto.SHA256, nil
 	case HKDFSHA384:
 		return crypto.SHA384, nil
 	case HKDFSHA512:
 		return crypto.SHA512, nil
 	}
 	return 0, fmt.Errorf("unknown KDF: %d", kdf)
 }

 type GenerateKeyPairFunc func() (public []byte, secret []byte, e error)

 // Context holds the HPKE state for a sender or a receiver.
 type Context struct {
 	kemID  uint16
 	kdfID  uint16
 	aeadID uint16

 	aead cipher.AEAD

 	key            []byte
 	baseNonce      []byte
 	seq            uint64
 	exporterSecret []byte
 }

 // SetupBaseSenderX25519 corresponds to the spec's SetupBaseS(), but only
 // supports X25519.
 func SetupBaseSenderX25519(kdfID, aeadID uint16, publicKeyR, info []byte, ephemKeygen GenerateKeyPairFunc) (context *Context, enc []byte, err error) {
 	sharedSecret, enc, err := x25519Encap(publicKeyR, ephemKeygen)
 	if err != nil {
 		return nil, nil, err
 	}
 	context, err = keySchedule(hpkeModeBase, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, nil, nil)
 	return
 }

 // SetupBaseReceiverX25519 corresponds to the spec's SetupBaseR(), but only
 // supports X25519.
 func SetupBaseReceiverX25519(kdfID, aeadID uint16, enc, secretKeyR, info []byte) (context *Context, err error) {
 	sharedSecret, err := x25519Decap(enc, secretKeyR)
 	if err != nil {
 		return nil, err
 	}
 	return keySchedule(hpkeModeBase, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, nil, nil)
 }

 // SetupPSKSenderX25519 corresponds to the spec's SetupPSKS(), but only supports
 // X25519.
 func SetupPSKSenderX25519(kdfID, aeadID uint16, publicKeyR, info, psk, pskID []byte, ephemKeygen GenerateKeyPairFunc) (context *Context, enc []byte, err error) {
 	sharedSecret, enc, err := x25519Encap(publicKeyR, ephemKeygen)
 	if err != nil {
 		return nil, nil, err
 	}
 	context, err = keySchedule(hpkeModePSK, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, psk, pskID)
 	return
 }

 // SetupPSKReceiverX25519 corresponds to the spec's SetupPSKR(), but only
 // supports X25519.
 func SetupPSKReceiverX25519(kdfID, aeadID uint16, enc, secretKeyR, info, psk, pskID []byte) (context *Context, err error) {
 	sharedSecret, err := x25519Decap(enc, secretKeyR)
 	if err != nil {
 		return nil, err
 	}
 	context, err = keySchedule(hpkeModePSK, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, psk, pskID)
 	if err != nil {
 		return nil, err
 	}
 	return context, nil
 }

 func (c *Context) KEM() uint16 { return c.kemID }

 func (c *Context) KDF() uint16 { return c.kdfID }

 func (c *Context) AEAD() uint16 { return c.aeadID }

 func (c *Context) Overhead() int { return c.aead.Overhead() }

 func (c *Context) Seal(plaintext, additionalData []byte) []byte {
 	ciphertext := c.aead.Seal(nil, c.computeNonce(), plaintext, additionalData)
 	c.incrementSeq()
 	return ciphertext
 }

 func (c *Context) Open(ciphertext, additionalData []byte) ([]byte, error) {
 	plaintext, err := c.aead.Open(nil, c.computeNonce(), ciphertext, additionalData)
 	if err != nil {
 		return nil, err
 	}
 	c.incrementSeq()
 	return plaintext, nil
 }

 func (c *Context) Export(exporterContext []byte, length int) []byte {
 	suiteID := buildSuiteID(c.kemID, c.kdfID, c.aeadID)
 	kdfHash := getKDFHash(c.kdfID)
 	return labeledExpand(kdfHash, c.exporterSecret, suiteID, []byte("sec"), exporterContext, length)
 }

 func buildSuiteID(kemID, kdfID, aeadID uint16) []byte {
 	ret := make([]byte, 0, 10)
 	ret = append(ret, "HPKE"...)
 	ret = appendBigEndianUint16(ret, kemID)
 	ret = appendBigEndianUint16(ret, kdfID)
 	ret = appendBigEndianUint16(ret, aeadID)
 	return ret
 }

 func newAEAD(aeadID uint16, key []byte) (cipher.AEAD, error) {
 	if len(key) != expectedKeyLength(aeadID) {
 		return nil, errors.New("wrong key length for specified AEAD")
 	}
 	switch aeadID {
 	case AES128GCM, AES256GCM:
 		block, err := aes.NewCipher(key)
 		if err != nil {
 			return nil, err
 		}
 		aead, err := cipher.NewGCM(block)
 		if err != nil {
 			return nil, err
 		}
 		return aead, nil
 	case ChaCha20Poly1305:
 		aead, err := chacha20poly1305.New(key)
 		if err != nil {
 			return nil, err
 		}
 		return aead, nil
 	}
 	return nil, errors.New("unsupported AEAD")
 }

 func keySchedule(mode uint8, kemID, kdfID, aeadID uint16, sharedSecret, info, psk, pskID []byte) (*Context, error) {
 	// Verify the PSK inputs.
 	switch mode {
 	case hpkeModeBase:
 		if len(psk) > 0 || len(pskID) > 0 {
 			panic("unnecessary psk inputs were provided")
 		}
 	case hpkeModePSK:
 		if len(psk) == 0 || len(pskID) == 0 {
 			panic("missing psk inputs")
 		}
 	default:
 		panic("unknown mode")
 	}

 	kdfHash := getKDFHash(kdfID)
 	suiteID := buildSuiteID(kemID, kdfID, aeadID)
 	pskIDHash := labeledExtract(kdfHash, nil, suiteID, []byte("psk_id_hash"), pskID)
 	infoHash := labeledExtract(kdfHash, nil, suiteID, []byte("info_hash"), info)

 	keyScheduleContext := make([]byte, 0)
 	keyScheduleContext = append(keyScheduleContext, mode)
 	keyScheduleContext = append(keyScheduleContext, pskIDHash...)
 	keyScheduleContext = append(keyScheduleContext, infoHash...)

 	secret := labeledExtract(kdfHash, sharedSecret, suiteID, []byte("secret"), psk)
 	key := labeledExpand(kdfHash, secret, suiteID, []byte("key"), keyScheduleContext, expectedKeyLength(aeadID))

 	aead, err := newAEAD(aeadID, key)
 	if err != nil {
 		return nil, err
 	}

 	baseNonce := labeledExpand(kdfHash, secret, suiteID, []byte("base_nonce"), keyScheduleContext, aead.NonceSize())
 	exporterSecret := labeledExpand(kdfHash, secret, suiteID, []byte("exp"), keyScheduleContext, kdfHash.Size())

 	return &Context{
 		kemID:          kemID,
 		kdfID:          kdfID,
 		aeadID:         aeadID,
 		aead:           aead,
 		key:            key,
 		baseNonce:      baseNonce,
 		seq:            0,
 		exporterSecret: exporterSecret,
 	}, nil
 }

 func (c Context) computeNonce() []byte {
 	nonce := make([]byte, len(c.baseNonce))
 	// Write the big-endian |c.seq| value at the *end* of |baseNonce|.
 	binary.BigEndian.PutUint64(nonce[len(nonce)-8:], c.seq)
 	// XOR the big-endian |seq| with |c.baseNonce|.
 	for i, b := range c.baseNonce {
 		nonce[i] ^= b
 	}
 	return nonce
 }

 func (c *Context) incrementSeq() {
 	c.seq++
 	if c.seq == 0 {
 		panic("sequence overflow")
 	}
 }

 func expectedKeyLength(aeadID uint16) int {
 	switch aeadID {
 	case AES128GCM:
 		return 128 / 8
 	case AES256GCM:
 		return 256 / 8
 	case ChaCha20Poly1305:
 		return chacha20poly1305.KeySize
 	}
 	panic("unsupported AEAD")
 }

 func appendBigEndianUint16(b []byte, v uint16) []byte {
 	return append(b, byte(v>>8), byte(v))
 }
	// Copyright (c) 2020, Google Inc.
	//
	// Permission to use, copy, modify, and/or distribute this software for any
	// purpose with or without fee is hereby granted, provided that the above
	// copyright notice and this permission notice appear in all copies.
	//
	// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
	// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
	// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
	// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

	// Package hpke implements Hybrid Public Key Encryption (HPKE).
	//
	// See https://tools.ietf.org/html/draft-irtf-cfrg-hpke-12.
	package hpke

	import (
	"crypto"
	"crypto/aes"
	"crypto/cipher"
	"encoding/binary"
	"errors"
	"fmt"

	"golang.org/x/crypto/chacha20poly1305"
	)

	// KEM scheme IDs.
	const (
	P256WithHKDFSHA256 uint16 = 0x0010
	X25519WithHKDFSHA256 uint16 = 0x0020
	)

	// HPKE AEAD IDs.
	const (
	AES128GCM uint16 = 0x0001
	AES256GCM uint16 = 0x0002
	ChaCha20Poly1305 uint16 = 0x0003
	)

	// HPKE KDF IDs.
	const (
	HKDFSHA256 uint16 = 0x0001
	HKDFSHA384 uint16 = 0x0002
	HKDFSHA512 uint16 = 0x0003
	)

	// Internal constants.
	const (
	hpkeModeBase uint8 = 0
	hpkeModePSK uint8 = 1
	)

	// GetHKDFHash returns the crypto.Hash that corresponds to kdf. If kdf is not
	// one the supported KDF IDs, returns an error.
	func GetHKDFHash(kdf uint16) (crypto.Hash, error) {
	switch kdf {
	case HKDFSHA256:
	return crypto.SHA256, nil
	case HKDFSHA384:
	return crypto.SHA384, nil
	case HKDFSHA512:
	return crypto.SHA512, nil
	}
	return 0, fmt.Errorf("unknown KDF: %d", kdf)
	}

	type GenerateKeyPairFunc func() (public []byte, secret []byte, e error)

	// Context holds the HPKE state for a sender or a receiver.
	type Context struct {
	kemID uint16
	kdfID uint16
	aeadID uint16

	aead cipher.AEAD

	key []byte
	baseNonce []byte
	seq uint64
	exporterSecret []byte
	}

	// SetupBaseSenderX25519 corresponds to the spec's SetupBaseS(), but only
	// supports X25519.
	func SetupBaseSenderX25519(kdfID, aeadID uint16, publicKeyR, info []byte, ephemKeygen GenerateKeyPairFunc) (context *Context, enc []byte, err error) {
	sharedSecret, enc, err := x25519Encap(publicKeyR, ephemKeygen)
	if err != nil {
	return nil, nil, err
	}
	context, err = keySchedule(hpkeModeBase, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, nil, nil)
	return
	}

	// SetupBaseReceiverX25519 corresponds to the spec's SetupBaseR(), but only
	// supports X25519.
	func SetupBaseReceiverX25519(kdfID, aeadID uint16, enc, secretKeyR, info []byte) (context *Context, err error) {
	sharedSecret, err := x25519Decap(enc, secretKeyR)
	if err != nil {
	return nil, err
	}
	return keySchedule(hpkeModeBase, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, nil, nil)
	}

	// SetupPSKSenderX25519 corresponds to the spec's SetupPSKS(), but only supports
	// X25519.
	func SetupPSKSenderX25519(kdfID, aeadID uint16, publicKeyR, info, psk, pskID []byte, ephemKeygen GenerateKeyPairFunc) (context *Context, enc []byte, err error) {
	sharedSecret, enc, err := x25519Encap(publicKeyR, ephemKeygen)
	if err != nil {
	return nil, nil, err
	}
	context, err = keySchedule(hpkeModePSK, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, psk, pskID)
	return
	}

	// SetupPSKReceiverX25519 corresponds to the spec's SetupPSKR(), but only
	// supports X25519.
	func SetupPSKReceiverX25519(kdfID, aeadID uint16, enc, secretKeyR, info, psk, pskID []byte) (context *Context, err error) {
	sharedSecret, err := x25519Decap(enc, secretKeyR)
	if err != nil {
	return nil, err
	}
	context, err = keySchedule(hpkeModePSK, X25519WithHKDFSHA256, kdfID, aeadID, sharedSecret, info, psk, pskID)
	if err != nil {
	return nil, err
	}
	return context, nil
	}

	func (c *Context) KEM() uint16 { return c.kemID }

	func (c *Context) KDF() uint16 { return c.kdfID }

	func (c *Context) AEAD() uint16 { return c.aeadID }

	func (c *Context) Overhead() int { return c.aead.Overhead() }

	func (c *Context) Seal(plaintext, additionalData []byte) []byte {
	ciphertext := c.aead.Seal(nil, c.computeNonce(), plaintext, additionalData)
	c.incrementSeq()
	return ciphertext
	}

	func (c *Context) Open(ciphertext, additionalData []byte) ([]byte, error) {
	plaintext, err := c.aead.Open(nil, c.computeNonce(), ciphertext, additionalData)
	if err != nil {
	return nil, err
	}
	c.incrementSeq()
	return plaintext, nil
	}

	func (c *Context) Export(exporterContext []byte, length int) []byte {
	suiteID := buildSuiteID(c.kemID, c.kdfID, c.aeadID)
	kdfHash := getKDFHash(c.kdfID)
	return labeledExpand(kdfHash, c.exporterSecret, suiteID, []byte("sec"), exporterContext, length)
	}

	func buildSuiteID(kemID, kdfID, aeadID uint16) []byte {
	ret := make([]byte, 0, 10)
	ret = append(ret, "HPKE"...)
	ret = appendBigEndianUint16(ret, kemID)
	ret = appendBigEndianUint16(ret, kdfID)
	ret = appendBigEndianUint16(ret, aeadID)
	return ret
	}

	func newAEAD(aeadID uint16, key []byte) (cipher.AEAD, error) {
	if len(key) != expectedKeyLength(aeadID) {
	return nil, errors.New("wrong key length for specified AEAD")
	}
	switch aeadID {
	case AES128GCM, AES256GCM:
	block, err := aes.NewCipher(key)
	if err != nil {
	return nil, err
	}
	aead, err := cipher.NewGCM(block)
	if err != nil {
	return nil, err
	}
	return aead, nil
	case ChaCha20Poly1305:
	aead, err := chacha20poly1305.New(key)
	if err != nil {
	return nil, err
	}
	return aead, nil
	}
	return nil, errors.New("unsupported AEAD")
	}

	func keySchedule(mode uint8, kemID, kdfID, aeadID uint16, sharedSecret, info, psk, pskID []byte) (*Context, error) {
	// Verify the PSK inputs.
	switch mode {
	case hpkeModeBase:
	if len(psk) > 0 \|\| len(pskID) > 0 {
	panic("unnecessary psk inputs were provided")
	}
	case hpkeModePSK:
	if len(psk) == 0 \|\| len(pskID) == 0 {
	panic("missing psk inputs")
	}
	default:
	panic("unknown mode")
	}

	kdfHash := getKDFHash(kdfID)
	suiteID := buildSuiteID(kemID, kdfID, aeadID)
	pskIDHash := labeledExtract(kdfHash, nil, suiteID, []byte("psk_id_hash"), pskID)
	infoHash := labeledExtract(kdfHash, nil, suiteID, []byte("info_hash"), info)

	keyScheduleContext := make([]byte, 0)
	keyScheduleContext = append(keyScheduleContext, mode)
	keyScheduleContext = append(keyScheduleContext, pskIDHash...)
	keyScheduleContext = append(keyScheduleContext, infoHash...)

	secret := labeledExtract(kdfHash, sharedSecret, suiteID, []byte("secret"), psk)
	key := labeledExpand(kdfHash, secret, suiteID, []byte("key"), keyScheduleContext, expectedKeyLength(aeadID))

	aead, err := newAEAD(aeadID, key)
	if err != nil {
	return nil, err
	}

	baseNonce := labeledExpand(kdfHash, secret, suiteID, []byte("base_nonce"), keyScheduleContext, aead.NonceSize())
	exporterSecret := labeledExpand(kdfHash, secret, suiteID, []byte("exp"), keyScheduleContext, kdfHash.Size())

	return &Context{
	kemID: kemID,
	kdfID: kdfID,
	aeadID: aeadID,
	aead: aead,
	key: key,
	baseNonce: baseNonce,
	seq: 0,
	exporterSecret: exporterSecret,
	}, nil
	}

	func (c Context) computeNonce() []byte {
	nonce := make([]byte, len(c.baseNonce))
	// Write the big-endian \|c.seq\| value at the end of \|baseNonce\|.
	binary.BigEndian.PutUint64(nonce[len(nonce)-8:], c.seq)
	// XOR the big-endian \|seq\| with \|c.baseNonce\|.
	for i, b := range c.baseNonce {
	nonce[i] ^= b
	}
	return nonce
	}

	func (c *Context) incrementSeq() {
	c.seq++
	if c.seq == 0 {
	panic("sequence overflow")
	}
	}

	func expectedKeyLength(aeadID uint16) int {
	switch aeadID {
	case AES128GCM:
	return 128 / 8
	case AES256GCM:
	return 256 / 8
	case ChaCha20Poly1305:
	return chacha20poly1305.KeySize
	}
	panic("unsupported AEAD")
	}

	func appendBigEndianUint16(b []byte, v uint16) []byte {
	return append(b, byte(v>>8), byte(v))
	}