From 513b786694d99a0dfeff7efbbeecbf4b8f6e823a Mon Sep 17 00:00:00 2001
From: Emman <emman.sun@cargosmart.com>
Date: Wed, 31 Mar 2021 12:01:22 +0800
Subject: [PATCH] MAGIC - add license

---
 cipher/ccm.go         | 4 ++--
 cipher/ccm_test.go    | 1 +
 cipher/xor_amd64.go   | 4 ++++
 cipher/xor_amd64.s    | 4 ++++
 cipher/xor_generic.go | 6 +++++-
 5 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/cipher/ccm.go b/cipher/ccm.go
index bd39acb..b3f9b2d 100644
--- a/cipher/ccm.go
+++ b/cipher/ccm.go
@@ -127,8 +127,8 @@ func (c *ccm) auth(nonce, plaintext, additionalData []byte, tagMask *[ccmBlockSi
 	if len(additionalData) > 0 {
 		out[0] = 1 << 6 // 64*Adata
 	}
-	out[0] |= byte(c.tagSize-2) << 2
-	out[0] |= byte(14 - c.nonceSize)
+	out[0] |= byte(c.tagSize-2) << 2 // M' = ((tagSize - 2) / 2)*8
+	out[0] |= byte(14 - c.nonceSize) // L'
 	binary.BigEndian.PutUint64(out[ccmBlockSize-8:], uint64(len(plaintext)))
 	copy(out[1:], nonce)
 	c.cipher.Encrypt(out[:], out[:])
diff --git a/cipher/ccm_test.go b/cipher/ccm_test.go
index b0febb2..ddb2d46 100644
--- a/cipher/ccm_test.go
+++ b/cipher/ccm_test.go
@@ -6,6 +6,7 @@ import (
 	"testing"
 )
 
+// https://tools.ietf.org/html/rfc3610, 8. Test Vectors
 var aesCCMTests = []struct {
 	key, nonce, plaintext, ad, result string
 	tagSize                           int
diff --git a/cipher/xor_amd64.go b/cipher/xor_amd64.go
index 4db7b3f..07e4d0f 100644
--- a/cipher/xor_amd64.go
+++ b/cipher/xor_amd64.go
@@ -1,3 +1,7 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package cipher
 
 // XorBytes xors the bytes in a and b. The destination should have enough
diff --git a/cipher/xor_amd64.s b/cipher/xor_amd64.s
index dfd40b4..8085d28 100644
--- a/cipher/xor_amd64.s
+++ b/cipher/xor_amd64.s
@@ -1,3 +1,7 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 #include "textflag.h"
 
 // func xorBytesSSE2(dst, a, b *byte, n int)
diff --git a/cipher/xor_generic.go b/cipher/xor_generic.go
index cac5843..b7451ea 100644
--- a/cipher/xor_generic.go
+++ b/cipher/xor_generic.go
@@ -1,3 +1,7 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 // +build !amd64
 
 package cipher
@@ -84,4 +88,4 @@ func XorWords(dst, a, b []byte) {
 	} else {
 		safeXORBytes(dst, a, b, len(b))
 	}
-}
\ No newline at end of file
+}