forked from quic-go/quic-go
/
null_aead_fnv128a.go
79 lines (66 loc) · 1.86 KB
/
null_aead_fnv128a.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
package crypto
import (
"bytes"
"errors"
"fmt"
"hash/fnv"
"github.com/lucas-clemente/quic-go/internal/protocol"
)
// nullAEAD handles not-yet encrypted packets
type nullAEADFNV128a struct {
perspective protocol.Perspective
}
var _ AEAD = &nullAEADFNV128a{}
// Open and verify the ciphertext
func (n *nullAEADFNV128a) Open(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) ([]byte, error) {
if len(src) < 12 {
return nil, errors.New("NullAEAD: ciphertext cannot be less than 12 bytes long")
}
hash := fnv.New128a()
hash.Write(associatedData)
hash.Write(src[12:])
if n.perspective == protocol.PerspectiveServer {
hash.Write([]byte("Client"))
} else {
hash.Write([]byte("Server"))
}
sum := make([]byte, 0, 16)
sum = hash.Sum(sum)
// The tag is written in little endian, so we need to reverse the slice.
reverse(sum)
if !bytes.Equal(sum[:12], src[:12]) {
return nil, fmt.Errorf("NullAEAD: failed to authenticate received data (%#v vs %#v)", sum[:12], src[:12])
}
return src[12:], nil
}
// Seal writes hash and ciphertext to the buffer
func (n *nullAEADFNV128a) Seal(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) []byte {
if cap(dst) < 12+len(src) {
dst = make([]byte, 12+len(src))
} else {
dst = dst[:12+len(src)]
}
hash := fnv.New128a()
hash.Write(associatedData)
hash.Write(src)
if n.perspective == protocol.PerspectiveServer {
hash.Write([]byte("Server"))
} else {
hash.Write([]byte("Client"))
}
sum := make([]byte, 0, 16)
sum = hash.Sum(sum)
// The tag is written in little endian, so we need to reverse the slice.
reverse(sum)
copy(dst[12:], src)
copy(dst, sum[:12])
return dst
}
func (n *nullAEADFNV128a) Overhead() int {
return 12
}
func reverse(a []byte) {
for left, right := 0, len(a)-1; left < right; left, right = left+1, right-1 {
a[left], a[right] = a[right], a[left]
}
}