1 files changed, 41 insertions, 0 deletions
diff --git a/vendor/go.mau.fi/whatsmeow/util/gcmutil/gcm.go b/vendor/go.mau.fi/whatsmeow/util/gcmutil/gcm.go
new file mode 100644
index 00000000..2451aeab
--- /dev/null
+++ b/vendor/go.mau.fi/whatsmeow/util/gcmutil/gcm.go
@@ -0,0 +1,41 @@
+// Copyright (c) 2022 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 gcmutil
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"fmt"
+)
+
+func Prepare(secretKey []byte) (gcm cipher.AEAD, err error) {
+	var block cipher.Block
+	if block, err = aes.NewCipher(secretKey); err != nil {
+		err = fmt.Errorf("failed to initialize AES cipher: %w", err)
+	} else if gcm, err = cipher.NewGCM(block); err != nil {
+		err = fmt.Errorf("failed to initialize GCM: %w", err)
+	}
+	return
+}
+
+func Decrypt(secretKey, iv, ciphertext, additionalData []byte) ([]byte, error) {
+	if gcm, err := Prepare(secretKey); err != nil {
+		return nil, err
+	} else if plaintext, decryptErr := gcm.Open(nil, iv, ciphertext, additionalData); decryptErr != nil {
+		return nil, decryptErr
+	} else {
+		return plaintext, nil
+	}
+}
+
+func Encrypt(secretKey, iv, plaintext, additionalData []byte) ([]byte, error) {
+	if gcm, err := Prepare(secretKey); err != nil {
+		return nil, err
+	} else {
+		return gcm.Seal(nil, iv, plaintext, additionalData), nil
+	}
+}