crypto: Switch hkdfchacha back to xchacha (#2058)

hkdfchachapoly was a construction we came up with. There is no longer any
reason to use it. We should instead just use xchacha for the remaining use
cases we have. (Symmetrically encrypting the keys in the sdk keys package)

CHANGELOG_PENDING.md

@@ -15,6 +15,7 @@ IMPROVEMENTS:
 - [blockchain] Improve fast-sync logic
     - tweak params
     - only process one block at a time to avoid starving
+- [crypto] Switch hkdfchachapoly1305 to xchachapoly1305
 
 BUG FIXES:
 - [privval] fix a deadline for accepting new connections in socket private

crypto/hkdfchacha20poly1305/hkdfchachapoly.go

@@ -1,106 +0,0 @@
-// Package hkdfchacha20poly1305 creates an AEAD using hkdf, chacha20, and poly1305
-// When sealing and opening, the hkdf is used to obtain the nonce and subkey for
-// chacha20. Other than the change for the how the subkey and nonce for chacha
-// are obtained, this is the same as chacha20poly1305
-package hkdfchacha20poly1305
-
-import (
-	"crypto/cipher"
-	"crypto/sha256"
-	"errors"
-	"io"
-
-	"golang.org/x/crypto/chacha20poly1305"
-	"golang.org/x/crypto/hkdf"
-)
-
-// Implements crypto.AEAD
-type hkdfchacha20poly1305 struct {
-	key [KeySize]byte
-}
-
-const (
-	// KeySize is the size of the key used by this AEAD, in bytes.
-	KeySize = 32
-	// NonceSize is the size of the nonce used with this AEAD, in bytes.
-	NonceSize = 24
-	// TagSize is the size added from poly1305
-	TagSize = 16
-	// MaxPlaintextSize is the max size that can be passed into a single call of Seal
-	MaxPlaintextSize = (1 << 38) - 64
-	// MaxCiphertextSize is the max size that can be passed into a single call of Open,
-	// this differs from plaintext size due to the tag
-	MaxCiphertextSize = (1 << 38) - 48
-	// HkdfInfo is the parameter used internally for Hkdf's info parameter.
-	HkdfInfo = "TENDERMINT_SECRET_CONNECTION_FRAME_KEY_DERIVE"
-)
-
-//New xChaChapoly1305 AEAD with 24 byte nonces
-func New(key []byte) (cipher.AEAD, error) {
-	if len(key) != KeySize {
-		return nil, errors.New("chacha20poly1305: bad key length")
-	}
-	ret := new(hkdfchacha20poly1305)
-	copy(ret.key[:], key)
-	return ret, nil
-
-}
-func (c *hkdfchacha20poly1305) NonceSize() int {
-	return NonceSize
-}
-
-func (c *hkdfchacha20poly1305) Overhead() int {
-	return TagSize
-}
-
-func (c *hkdfchacha20poly1305) Seal(dst, nonce, plaintext, additionalData []byte) []byte {
-	if len(nonce) != NonceSize {
-		panic("hkdfchacha20poly1305: bad nonce length passed to Seal")
-	}
-
-	if uint64(len(plaintext)) > MaxPlaintextSize {
-		panic("hkdfchacha20poly1305: plaintext too large")
-	}
-
-	subKey, chachaNonce := getSubkeyAndChachaNonceFromHkdf(&c.key, &nonce)
-
-	aead, err := chacha20poly1305.New(subKey[:])
-	if err != nil {
-		panic("hkdfchacha20poly1305: failed to initialize chacha20poly1305")
-	}
-
-	return aead.Seal(dst, chachaNonce[:], plaintext, additionalData)
-}
-
-func (c *hkdfchacha20poly1305) Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) {
-	if len(nonce) != NonceSize {
-		return nil, errors.New("hkdfchacha20poly1305: bad nonce length passed to Open")
-	}
-	if uint64(len(ciphertext)) > MaxCiphertextSize {
-		return nil, errors.New("hkdfchacha20poly1305: ciphertext too large")
-	}
-
-	subKey, chachaNonce := getSubkeyAndChachaNonceFromHkdf(&c.key, &nonce)
-
-	aead, err := chacha20poly1305.New(subKey[:])
-	if err != nil {
-		panic("hkdfchacha20poly1305: failed to initialize chacha20poly1305")
-	}
-
-	return aead.Open(dst, chachaNonce[:], ciphertext, additionalData)
-}
-
-func getSubkeyAndChachaNonceFromHkdf(cKey *[32]byte, nonce *[]byte) (
-	subKey [KeySize]byte, chachaNonce [chacha20poly1305.NonceSize]byte) {
-	hash := sha256.New
-	hkdf := hkdf.New(hash, (*cKey)[:], *nonce, []byte(HkdfInfo))
-	_, err := io.ReadFull(hkdf, subKey[:])
-	if err != nil {
-		panic("hkdfchacha20poly1305: failed to read subkey from hkdf")
-	}
-	_, err = io.ReadFull(hkdf, chachaNonce[:])
-	if err != nil {
-		panic("hkdfchacha20poly1305: failed to read chachaNonce from hkdf")
-	}
-	return
-}

crypto/xchacha20poly1305/vector_test.go

@@ -0,0 +1,103 @@
+package xchacha20poly1305
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+)
+
+func toHex(bits []byte) string {
+	return hex.EncodeToString(bits)
+}
+
+func fromHex(bits string) []byte {
+	b, err := hex.DecodeString(bits)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}
+
+func TestHChaCha20(t *testing.T) {
+	for i, v := range hChaCha20Vectors {
+		var key [32]byte
+		var nonce [16]byte
+		copy(key[:], v.key)
+		copy(nonce[:], v.nonce)
+
+		HChaCha20(&key, &nonce, &key)
+		if !bytes.Equal(key[:], v.keystream) {
+			t.Errorf("Test %d: keystream mismatch:\n \t got:  %s\n \t want: %s", i, toHex(key[:]), toHex(v.keystream))
+		}
+	}
+}
+
+var hChaCha20Vectors = []struct {
+	key, nonce, keystream []byte
+}{
+	{
+		fromHex("0000000000000000000000000000000000000000000000000000000000000000"),
+		fromHex("000000000000000000000000000000000000000000000000"),
+		fromHex("1140704c328d1d5d0e30086cdf209dbd6a43b8f41518a11cc387b669b2ee6586"),
+	},
+	{
+		fromHex("8000000000000000000000000000000000000000000000000000000000000000"),
+		fromHex("000000000000000000000000000000000000000000000000"),
+		fromHex("7d266a7fd808cae4c02a0a70dcbfbcc250dae65ce3eae7fc210f54cc8f77df86"),
+	},
+	{
+		fromHex("0000000000000000000000000000000000000000000000000000000000000001"),
+		fromHex("000000000000000000000000000000000000000000000002"),
+		fromHex("e0c77ff931bb9163a5460c02ac281c2b53d792b1c43fea817e9ad275ae546963"),
+	},
+	{
+		fromHex("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f"),
+		fromHex("000102030405060708090a0b0c0d0e0f1011121314151617"),
+		fromHex("51e3ff45a895675c4b33b46c64f4a9ace110d34df6a2ceab486372bacbd3eff6"),
+	},
+	{
+		fromHex("24f11cce8a1b3d61e441561a696c1c1b7e173d084fd4812425435a8896a013dc"),
+		fromHex("d9660c5900ae19ddad28d6e06e45fe5e"),
+		fromHex("5966b3eec3bff1189f831f06afe4d4e3be97fa9235ec8c20d08acfbbb4e851e3"),
+	},
+}
+
+func TestVectors(t *testing.T) {
+	for i, v := range vectors {
+		if len(v.plaintext) == 0 {
+			v.plaintext = make([]byte, len(v.ciphertext))
+		}
+
+		var nonce [24]byte
+		copy(nonce[:], v.nonce)
+
+		aead, err := New(v.key)
+		if err != nil {
+			t.Error(err)
+		}
+
+		dst := aead.Seal(nil, nonce[:], v.plaintext, v.ad)
+		if !bytes.Equal(dst, v.ciphertext) {
+			t.Errorf("Test %d: ciphertext mismatch:\n \t got:  %s\n \t want: %s", i, toHex(dst), toHex(v.ciphertext))
+		}
+		open, err := aead.Open(nil, nonce[:], dst, v.ad)
+		if err != nil {
+			t.Error(err)
+		}
+		if !bytes.Equal(open, v.plaintext) {
+			t.Errorf("Test %d: plaintext mismatch:\n \t got:  %s\n \t want: %s", i, string(open), string(v.plaintext))
+		}
+	}
+}
+
+var vectors = []struct {
+	key, nonce, ad, plaintext, ciphertext []byte
+}{
+	{
+		[]byte{0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f},
+		[]byte{0x07, 0x00, 0x00, 0x00, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b},
+		[]byte{0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7},
+		[]byte("Ladies and Gentlemen of the class of '99: If I could offer you only one tip for the future, sunscreen would be it."),
+		[]byte{0x45, 0x3c, 0x06, 0x93, 0xa7, 0x40, 0x7f, 0x04, 0xff, 0x4c, 0x56, 0xae, 0xdb, 0x17, 0xa3, 0xc0, 0xa1, 0xaf, 0xff, 0x01, 0x17, 0x49, 0x30, 0xfc, 0x22, 0x28, 0x7c, 0x33, 0xdb, 0xcf, 0x0a, 0xc8, 0xb8, 0x9a, 0xd9, 0x29, 0x53, 0x0a, 0x1b, 0xb3, 0xab, 0x5e, 0x69, 0xf2, 0x4c, 0x7f, 0x60, 0x70, 0xc8, 0xf8, 0x40, 0xc9, 0xab, 0xb4, 0xf6, 0x9f, 0xbf, 0xc8, 0xa7, 0xff, 0x51, 0x26, 0xfa, 0xee, 0xbb, 0xb5, 0x58, 0x05, 0xee, 0x9c, 0x1c, 0xf2, 0xce, 0x5a, 0x57, 0x26, 0x32, 0x87, 0xae, 0xc5, 0x78, 0x0f, 0x04, 0xec, 0x32, 0x4c, 0x35, 0x14, 0x12, 0x2c, 0xfc, 0x32, 0x31, 0xfc, 0x1a, 0x8b, 0x71, 0x8a, 0x62, 0x86, 0x37, 0x30, 0xa2, 0x70, 0x2b, 0xb7, 0x63, 0x66, 0x11, 0x6b, 0xed, 0x09, 0xe0, 0xfd, 0x5c, 0x6d, 0x84, 0xb6, 0xb0, 0xc1, 0xab, 0xaf, 0x24, 0x9d, 0x5d, 0xd0, 0xf7, 0xf5, 0xa7, 0xea},
+	},
+}

crypto/xchacha20poly1305/xchachapoly.go

@@ -0,0 +1,261 @@
+// Package xchacha20poly1305 creates an AEAD using hchacha, chacha, and poly1305
+// This allows for randomized nonces to be used in conjunction with chacha.
+package xchacha20poly1305
+
+import (
+	"crypto/cipher"
+	"encoding/binary"
+	"errors"
+	"fmt"
+
+	"golang.org/x/crypto/chacha20poly1305"
+)
+
+// Implements crypto.AEAD
+type xchacha20poly1305 struct {
+	key [KeySize]byte
+}
+
+const (
+	// KeySize is the size of the key used by this AEAD, in bytes.
+	KeySize = 32
+	// NonceSize is the size of the nonce used with this AEAD, in bytes.
+	NonceSize = 24
+	// TagSize is the size added from poly1305
+	TagSize = 16
+	// MaxPlaintextSize is the max size that can be passed into a single call of Seal
+	MaxPlaintextSize = (1 << 38) - 64
+	// MaxCiphertextSize is the max size that can be passed into a single call of Open,
+	// this differs from plaintext size due to the tag
+	MaxCiphertextSize = (1 << 38) - 48
+
+	// sigma are constants used in xchacha.
+	// Unrolled from a slice so that they can be inlined, as slices can't be constants.
+	sigma0 = uint32(0x61707865)
+	sigma1 = uint32(0x3320646e)
+	sigma2 = uint32(0x79622d32)
+	sigma3 = uint32(0x6b206574)
+)
+
+// New returns a new xchachapoly1305 AEAD
+func New(key []byte) (cipher.AEAD, error) {
+	if len(key) != KeySize {
+		return nil, errors.New("xchacha20poly1305: bad key length")
+	}
+	ret := new(xchacha20poly1305)
+	copy(ret.key[:], key)
+	return ret, nil
+}
+
+// nolint
+func (c *xchacha20poly1305) NonceSize() int {
+	return NonceSize
+}
+
+// nolint
+func (c *xchacha20poly1305) Overhead() int {
+	return TagSize
+}
+
+func (c *xchacha20poly1305) Seal(dst, nonce, plaintext, additionalData []byte) []byte {
+	if len(nonce) != NonceSize {
+		panic("xchacha20poly1305: bad nonce length passed to Seal")
+	}
+
+	if uint64(len(plaintext)) > MaxPlaintextSize {
+		panic("xchacha20poly1305: plaintext too large")
+	}
+
+	var subKey [KeySize]byte
+	var hNonce [16]byte
+	var subNonce [chacha20poly1305.NonceSize]byte
+	copy(hNonce[:], nonce[:16])
+
+	HChaCha20(&subKey, &hNonce, &c.key)
+
+	// This can't error because we always provide a correctly sized key
+	chacha20poly1305, _ := chacha20poly1305.New(subKey[:])
+
+	copy(subNonce[4:], nonce[16:])
+
+	return chacha20poly1305.Seal(dst, subNonce[:], plaintext, additionalData)
+}
+
+func (c *xchacha20poly1305) Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) {
+	if len(nonce) != NonceSize {
+		return nil, fmt.Errorf("xchacha20poly1305: bad nonce length passed to Open")
+	}
+	if uint64(len(ciphertext)) > MaxCiphertextSize {
+		return nil, fmt.Errorf("xchacha20poly1305: ciphertext too large")
+	}
+	var subKey [KeySize]byte
+	var hNonce [16]byte
+	var subNonce [chacha20poly1305.NonceSize]byte
+	copy(hNonce[:], nonce[:16])
+
+	HChaCha20(&subKey, &hNonce, &c.key)
+
+	// This can't error because we always provide a correctly sized key
+	chacha20poly1305, _ := chacha20poly1305.New(subKey[:])
+
+	copy(subNonce[4:], nonce[16:])
+
+	return chacha20poly1305.Open(dst, subNonce[:], ciphertext, additionalData)
+}
+
+// HChaCha exported from
+// https://github.com/aead/chacha20/blob/8b13a72661dae6e9e5dea04f344f0dc95ea29547/chacha/chacha_generic.go#L194
+// TODO: Add support for the different assembly instructions used there.
+
+// The MIT License (MIT)
+
+// Copyright (c) 2016 Andreas Auernhammer
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// HChaCha20 generates 32 pseudo-random bytes from a 128 bit nonce and a 256 bit secret key.
+// It can be used as a key-derivation-function (KDF).
+func HChaCha20(out *[32]byte, nonce *[16]byte, key *[32]byte) { hChaCha20Generic(out, nonce, key) }
+
+func hChaCha20Generic(out *[32]byte, nonce *[16]byte, key *[32]byte) {
+	v00 := sigma0
+	v01 := sigma1
+	v02 := sigma2
+	v03 := sigma3
+	v04 := binary.LittleEndian.Uint32(key[0:])
+	v05 := binary.LittleEndian.Uint32(key[4:])
+	v06 := binary.LittleEndian.Uint32(key[8:])
+	v07 := binary.LittleEndian.Uint32(key[12:])
+	v08 := binary.LittleEndian.Uint32(key[16:])
+	v09 := binary.LittleEndian.Uint32(key[20:])
+	v10 := binary.LittleEndian.Uint32(key[24:])
+	v11 := binary.LittleEndian.Uint32(key[28:])
+	v12 := binary.LittleEndian.Uint32(nonce[0:])
+	v13 := binary.LittleEndian.Uint32(nonce[4:])
+	v14 := binary.LittleEndian.Uint32(nonce[8:])
+	v15 := binary.LittleEndian.Uint32(nonce[12:])
+
+	for i := 0; i < 20; i += 2 {
+		v00 += v04
+		v12 ^= v00
+		v12 = (v12 << 16) | (v12 >> 16)
+		v08 += v12
+		v04 ^= v08
+		v04 = (v04 << 12) | (v04 >> 20)
+		v00 += v04
+		v12 ^= v00
+		v12 = (v12 << 8) | (v12 >> 24)
+		v08 += v12
+		v04 ^= v08
+		v04 = (v04 << 7) | (v04 >> 25)
+		v01 += v05
+		v13 ^= v01
+		v13 = (v13 << 16) | (v13 >> 16)
+		v09 += v13
+		v05 ^= v09
+		v05 = (v05 << 12) | (v05 >> 20)
+		v01 += v05
+		v13 ^= v01
+		v13 = (v13 << 8) | (v13 >> 24)
+		v09 += v13
+		v05 ^= v09
+		v05 = (v05 << 7) | (v05 >> 25)
+		v02 += v06
+		v14 ^= v02
+		v14 = (v14 << 16) | (v14 >> 16)
+		v10 += v14
+		v06 ^= v10
+		v06 = (v06 << 12) | (v06 >> 20)
+		v02 += v06
+		v14 ^= v02
+		v14 = (v14 << 8) | (v14 >> 24)
+		v10 += v14
+		v06 ^= v10
+		v06 = (v06 << 7) | (v06 >> 25)
+		v03 += v07
+		v15 ^= v03
+		v15 = (v15 << 16) | (v15 >> 16)
+		v11 += v15
+		v07 ^= v11
+		v07 = (v07 << 12) | (v07 >> 20)
+		v03 += v07
+		v15 ^= v03
+		v15 = (v15 << 8) | (v15 >> 24)
+		v11 += v15
+		v07 ^= v11
+		v07 = (v07 << 7) | (v07 >> 25)
+		v00 += v05
+		v15 ^= v00
+		v15 = (v15 << 16) | (v15 >> 16)
+		v10 += v15
+		v05 ^= v10
+		v05 = (v05 << 12) | (v05 >> 20)
+		v00 += v05
+		v15 ^= v00
+		v15 = (v15 << 8) | (v15 >> 24)
+		v10 += v15
+		v05 ^= v10
+		v05 = (v05 << 7) | (v05 >> 25)
+		v01 += v06
+		v12 ^= v01
+		v12 = (v12 << 16) | (v12 >> 16)
+		v11 += v12
+		v06 ^= v11
+		v06 = (v06 << 12) | (v06 >> 20)
+		v01 += v06
+		v12 ^= v01
+		v12 = (v12 << 8) | (v12 >> 24)
+		v11 += v12
+		v06 ^= v11
+		v06 = (v06 << 7) | (v06 >> 25)
+		v02 += v07
+		v13 ^= v02
+		v13 = (v13 << 16) | (v13 >> 16)
+		v08 += v13
+		v07 ^= v08
+		v07 = (v07 << 12) | (v07 >> 20)
+		v02 += v07
+		v13 ^= v02
+		v13 = (v13 << 8) | (v13 >> 24)
+		v08 += v13
+		v07 ^= v08
+		v07 = (v07 << 7) | (v07 >> 25)
+		v03 += v04
+		v14 ^= v03
+		v14 = (v14 << 16) | (v14 >> 16)
+		v09 += v14
+		v04 ^= v09
+		v04 = (v04 << 12) | (v04 >> 20)
+		v03 += v04
+		v14 ^= v03
+		v14 = (v14 << 8) | (v14 >> 24)
+		v09 += v14
+		v04 ^= v09
+		v04 = (v04 << 7) | (v04 >> 25)
+	}
+
+	binary.LittleEndian.PutUint32(out[0:], v00)
+	binary.LittleEndian.PutUint32(out[4:], v01)
+	binary.LittleEndian.PutUint32(out[8:], v02)
+	binary.LittleEndian.PutUint32(out[12:], v03)
+	binary.LittleEndian.PutUint32(out[16:], v12)
+	binary.LittleEndian.PutUint32(out[20:], v13)
+	binary.LittleEndian.PutUint32(out[24:], v14)
+	binary.LittleEndian.PutUint32(out[28:], v15)
+}