From 893704e38f1f59799e30429f7e69f4947def340c Mon Sep 17 00:00:00 2001
From: Lucas Clemente <lucas@clemente.io>
Date: Sun, 10 Apr 2016 20:23:51 +0200
Subject: [PATCH] implement sealing for NullAEAD

---
 crypto/AEAD.go          |  1 +
 crypto/NullAEAD.go      | 16 ++++++++++++++++
 crypto/NullAEAD_test.go |  9 +++++++++
 3 files changed, 26 insertions(+)

diff --git a/crypto/AEAD.go b/crypto/AEAD.go
index f92b90b4..8dff1545 100644
--- a/crypto/AEAD.go
+++ b/crypto/AEAD.go
@@ -8,4 +8,5 @@ import (
 // An AEAD implements QUIC's authenticated encryption and associated data
 type AEAD interface {
 	Open(associatedData []byte, ciphertext io.Reader) (*bytes.Reader, error)
+	Seal(b *bytes.Buffer, associatedData []byte, r *bytes.Reader)
 }
diff --git a/crypto/NullAEAD.go b/crypto/NullAEAD.go
index 7b726ac3..d3ebf8f7 100644
--- a/crypto/NullAEAD.go
+++ b/crypto/NullAEAD.go
@@ -6,6 +6,8 @@ import (
 	"errors"
 	"io"
 	"io/ioutil"
+
+	"github.com/lucas-clemente/quic-go/utils"
 )
 
 // NullAEAD handles not-yet encrypted packets
@@ -36,3 +38,17 @@ func (*NullAEAD) Open(associatedData []byte, r io.Reader) (*bytes.Reader, error)
 	}
 	return bytes.NewReader(ciphertext[12:]), nil
 }
+
+// Seal writes hash and ciphertext to the buffer
+func (*NullAEAD) Seal(b *bytes.Buffer, associatedData []byte, r *bytes.Reader) {
+	plaintext, _ := ioutil.ReadAll(r)
+
+	hash := New128a()
+	hash.Write(associatedData)
+	hash.Write(plaintext)
+	high, low := hash.Sum128()
+
+	utils.WriteUint64(b, low)
+	utils.WriteUint32(b, uint32(high))
+	b.Write(plaintext)
+}
diff --git a/crypto/NullAEAD_test.go b/crypto/NullAEAD_test.go
index 25952613..fe74bfb8 100644
--- a/crypto/NullAEAD_test.go
+++ b/crypto/NullAEAD_test.go
@@ -32,4 +32,13 @@ var _ = Describe("Crypto/NullAEAD", func() {
 		_, err := aead.Open(aad, bytes.NewReader(cipherText))
 		Expect(err).To(HaveOccurred())
 	})
+
+	It("seals", func() {
+		aad := []byte("All human beings are born free and equal in dignity and rights.")
+		plainText := []byte("They are endowed with reason and conscience and should act towards one another in a spirit of brotherhood.")
+		b := &bytes.Buffer{}
+		aead := &crypto.NullAEAD{}
+		aead.Seal(b, aad, bytes.NewReader(plainText))
+		Expect(b.Bytes()).To(Equal(append([]byte{0x98, 0x9b, 0x33, 0x3f, 0xe8, 0xde, 0x32, 0x5c, 0xa6, 0x7f, 0x9c, 0xf7}, []byte("They are endowed with reason and conscience and should act towards one another in a spirit of brotherhood.")...)))
+	})
 })