crypto/goolm: use golang.org/x/crypto/hkdf and remove crypto.HKDFSHA256

Signed-off-by: Sumner Evans <sumner.evans@automattic.com>

crypto/goolm/cipher/aes_sha256.go

@@ -2,8 +2,11 @@ package cipher
 
 import (
 	"bytes"
+	"crypto/sha256"
 	"io"
 
+	"golang.org/x/crypto/hkdf"
+
 	"maunium.net/go/mautrix/crypto/aescbc"
 	"maunium.net/go/mautrix/crypto/goolm/crypto"
 )
@@ -17,9 +20,9 @@ type derivedAESKeys struct {
 
 // deriveAESKeys derives three keys for the AESSHA256 cipher
 func deriveAESKeys(kdfInfo []byte, key []byte) (derivedAESKeys, error) {
-	hkdf := crypto.HKDFSHA256(key, nil, kdfInfo)
+	kdf := hkdf.New(sha256.New, key, nil, kdfInfo)
 	keymatter := make([]byte, 80)
-	_, err := io.ReadFull(hkdf, keymatter)
+	_, err := io.ReadFull(kdf, keymatter)
 	return derivedAESKeys{
 		key:     keymatter[:32],
 		hmacKey: keymatter[32:64],

crypto/goolm/crypto/hmac.go

@@ -3,9 +3,6 @@ package crypto
 import (
 	"crypto/hmac"
 	"crypto/sha256"
-	"io"
-
-	"golang.org/x/crypto/hkdf"
 )
 
 // HMACSHA256 returns the hash message authentication code with SHA-256 of the input with the key.
@@ -21,9 +18,3 @@ func SHA256(value []byte) []byte {
 	hash.Write(value)
 	return hash.Sum(nil)
 }
-
-// HKDFSHA256 is the key deivation function based on HMAC and returns a reader based on input. salt and info can both be nil.
-// The reader can be used to read an arbitary length of bytes which are based on all parameters.
-func HKDFSHA256(input, salt, info []byte) io.Reader {
-	return hkdf.New(sha256.New, input, salt, info)
-}

crypto/goolm/crypto/hmac_test.go

@@ -1,11 +1,13 @@
 package crypto_test
 
 import (
+	"crypto/sha256"
 	"encoding/base64"
 	"io"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"golang.org/x/crypto/hkdf"
 
 	"maunium.net/go/mautrix/crypto/goolm/crypto"
 )
@@ -22,22 +24,6 @@ func TestHMACSHA256(t *testing.T) {
 	assert.Equal(t, result, hash)
 }
 
-func TestHKDFSHA256(t *testing.T) {
-	message := []byte("test content")
-
-	hkdf := crypto.HKDFSHA256(message, nil, nil)
-	result := make([]byte, 32)
-	_, err := io.ReadFull(hkdf, result)
-	assert.NoError(t, err)
-
-	hkdf2 := crypto.HKDFSHA256(message, nil, nil)
-	result2 := make([]byte, 32)
-	_, err = io.ReadFull(hkdf2, result2)
-	assert.NoError(t, err)
-
-	assert.Equal(t, result, result2)
-}
-
 func TestSHA256Case1(t *testing.T) {
 	input := make([]byte, 0)
 	expected := []byte{
@@ -93,7 +79,7 @@ func TestHDKFCase1(t *testing.T) {
 		0x34, 0x00, 0x72, 0x08, 0xd5, 0xb8, 0x87, 0x18,
 		0x58, 0x65,
 	}
-	resultReader := crypto.HKDFSHA256(input, salt, info)
+	resultReader := hkdf.New(sha256.New, input, salt, info)
 	result = make([]byte, len(expectedHDKF))
 	_, err := io.ReadFull(resultReader, result)
 	assert.NoError(t, err)

crypto/goolm/ratchet/olm.go

@@ -2,9 +2,12 @@
 package ratchet
 
 import (
+	"crypto/sha256"
 	"fmt"
 	"io"
 
+	"golang.org/x/crypto/hkdf"
+
 	"maunium.net/go/mautrix/crypto/goolm/cipher"
 	"maunium.net/go/mautrix/crypto/goolm/crypto"
 	"maunium.net/go/mautrix/crypto/goolm/libolmpickle"
@@ -70,7 +73,7 @@ func New() *Ratchet {
 
 // InitializeAsBob initializes this ratchet from a receiving point of view (only first message).
 func (r *Ratchet) InitializeAsBob(sharedSecret []byte, theirRatchetKey crypto.Curve25519PublicKey) error {
-	derivedSecretsReader := crypto.HKDFSHA256(sharedSecret, nil, KdfInfo.Root)
+	derivedSecretsReader := hkdf.New(sha256.New, sharedSecret, nil, KdfInfo.Root)
 	derivedSecrets := make([]byte, 2*sharedKeyLength)
 	if _, err := io.ReadFull(derivedSecretsReader, derivedSecrets); err != nil {
 		return err
@@ -83,7 +86,7 @@ func (r *Ratchet) InitializeAsBob(sharedSecret []byte, theirRatchetKey crypto.Cu
 
 // InitializeAsAlice initializes this ratchet from a sending point of view (only first message).
 func (r *Ratchet) InitializeAsAlice(sharedSecret []byte, ourRatchetKey crypto.Curve25519KeyPair) error {
-	derivedSecretsReader := crypto.HKDFSHA256(sharedSecret, nil, KdfInfo.Root)
+	derivedSecretsReader := hkdf.New(sha256.New, sharedSecret, nil, KdfInfo.Root)
 	derivedSecrets := make([]byte, 2*sharedKeyLength)
 	if _, err := io.ReadFull(derivedSecretsReader, derivedSecrets); err != nil {
 		return err
@@ -192,7 +195,7 @@ func (r *Ratchet) advanceRootKey(newRatchetKey crypto.Curve25519KeyPair, oldRatc
 	if err != nil {
 		return nil, err
 	}
-	derivedSecretsReader := crypto.HKDFSHA256(sharedSecret, r.RootKey, KdfInfo.Ratchet)
+	derivedSecretsReader := hkdf.New(sha256.New, sharedSecret, r.RootKey, KdfInfo.Ratchet)
 	derivedSecrets := make([]byte, 2*sharedKeyLength)
 	if _, err := io.ReadFull(derivedSecretsReader, derivedSecrets); err != nil {
 		return nil, err