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
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
package cryptfs
// Implements cipher.AEAD with OpenSSL backend
import (
"bytes"
"github.com/spacemonkeygo/openssl"
)
type opensslGCM struct {
key [16]byte
}
func (be opensslGCM) Overhead() int {
return AUTH_TAG_LEN
}
func (be opensslGCM) NonceSize() int {
return NONCE_LEN
}
// Seal encrypts and authenticates plaintext, authenticates the
// additional data and appends the result to dst, returning the updated
// slice. The nonce must be NonceSize() bytes long and unique for all
// time, for a given key.
func (be opensslGCM) Seal(dst, nonce, plaintext, data []byte) []byte {
cipherBuf := bytes.NewBuffer(dst)
ectx, err := openssl.NewGCMEncryptionCipherCtx(128, nil, be.key[:], nonce[:])
if err != nil {
panic(err)
}
err = ectx.ExtraData(data)
if err != nil {
panic(err)
}
part, err := ectx.EncryptUpdate(plaintext)
if err != nil {
panic(err)
}
cipherBuf.Write(part)
part, err = ectx.EncryptFinal()
if err != nil {
panic(err)
}
cipherBuf.Write(part)
part, err = ectx.GetTag()
if err != nil {
panic(err)
}
cipherBuf.Write(part)
return cipherBuf.Bytes()
}
// Open decrypts and authenticates ciphertext, authenticates the
// additional data and, if successful, appends the resulting plaintext
// to dst, returning the updated slice. The nonce must be NonceSize()
// bytes long and both it and the additional data must match the
// value passed to Seal.
//
// The ciphertext and dst may alias exactly or not at all.
func (be opensslGCM) Open(dst, nonce, ciphertext, data []byte) ([]byte, error) {
if len(data) > 0 {
panic("Extra data is not supported")
}
l := len(ciphertext)
tag := ciphertext[l-AUTH_TAG_LEN : l]
ciphertext = ciphertext[0 : l-AUTH_TAG_LEN]
plainBuf := bytes.NewBuffer(dst)
dctx, err := openssl.NewGCMDecryptionCipherCtx(128, nil, be.key[:], nonce[:])
if err != nil {
return nil, err
}
part, err := dctx.DecryptUpdate(ciphertext)
if err != nil {
return nil, err
}
plainBuf.Write(part)
err = dctx.SetTag(tag)
if err != nil {
return nil, err
}
part, err = dctx.DecryptFinal()
if err != nil {
return nil, err
}
plainBuf.Write(part)
err = dctx.ExtraData(data)
if err != nil {
return nil, err
}
return plainBuf.Bytes(), nil
}
|
