Add dependencies/vendor (whatsapp)

vendor/go.mau.fi/whatsmeow/util/keys/keypair.go

@@ -0,0 +1,75 @@
+// Copyright (c) 2021 Tulir Asokan
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// Package keys contains a utility struct for elliptic curve keypairs.
+package keys
+
+import (
+	"crypto/rand"
+	"fmt"
+
+	"go.mau.fi/libsignal/ecc"
+	"golang.org/x/crypto/curve25519"
+)
+
+type KeyPair struct {
+	Pub  *[32]byte
+	Priv *[32]byte
+}
+
+var _ ecc.ECPublicKeyable
+
+func NewKeyPairFromPrivateKey(priv [32]byte) *KeyPair {
+	var kp KeyPair
+	kp.Priv = &priv
+	var pub [32]byte
+	curve25519.ScalarBaseMult(&pub, kp.Priv)
+	kp.Pub = &pub
+	return &kp
+}
+
+func NewKeyPair() *KeyPair {
+	var priv [32]byte
+
+	_, err := rand.Read(priv[:])
+	if err != nil {
+		panic(fmt.Errorf("failed to generate curve25519 private key: %w", err))
+	}
+
+	priv[0] &= 248
+	priv[31] &= 127
+	priv[31] |= 64
+
+	return NewKeyPairFromPrivateKey(priv)
+}
+
+func (kp *KeyPair) CreateSignedPreKey(keyID uint32) *PreKey {
+	newKey := NewPreKey(keyID)
+	newKey.Signature = kp.Sign(&newKey.KeyPair)
+	return newKey
+}
+
+func (kp *KeyPair) Sign(keyToSign *KeyPair) *[64]byte {
+	pubKeyForSignature := make([]byte, 33)
+	pubKeyForSignature[0] = ecc.DjbType
+	copy(pubKeyForSignature[1:], keyToSign.Pub[:])
+
+	signature := ecc.CalculateSignature(ecc.NewDjbECPrivateKey(*kp.Priv), pubKeyForSignature)
+	return &signature
+}
+
+type PreKey struct {
+	KeyPair
+	KeyID     uint32
+	Signature *[64]byte
+}
+
+func NewPreKey(keyID uint32) *PreKey {
+	return &PreKey{
+		KeyPair: *NewKeyPair(),
+		KeyID:   keyID,
+	}
+}