-
Notifications
You must be signed in to change notification settings - Fork 60
/
sm4_gcm_asm.go
159 lines (128 loc) · 4.54 KB
/
sm4_gcm_asm.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
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
//go:build (amd64 && !generic) || (arm64 && !generic)
// +build amd64,!generic arm64,!generic
package sm4
import (
"crypto/cipher"
"crypto/subtle"
"github.com/emmansun/gmsm/internal/alias"
)
// sm4CipherGCM implements crypto/cipher.gcmAble so that crypto/cipher.NewGCM
// will use the optimised implementation in this file when possible. Instances
// of this type only exist when hasGCMAsm and hasAES returns true.
type sm4CipherGCM struct {
*sm4CipherAsm
}
// Assert that sm4CipherGCM implements the gcmAble interface.
var _ gcmAble = (*sm4CipherGCM)(nil)
//go:noescape
func gcmSm4Init(productTable *[256]byte, rk []uint32, inst int)
//go:noescape
func gcmSm4Enc(productTable *[256]byte, dst, src []byte, ctr, T *[16]byte, rk []uint32)
//go:noescape
func gcmSm4Dec(productTable *[256]byte, dst, src []byte, ctr, T *[16]byte, rk []uint32)
//go:noescape
func gcmSm4Data(productTable *[256]byte, data []byte, T *[16]byte)
//go:noescape
func gcmSm4Finish(productTable *[256]byte, tagMask, T *[16]byte, pLen, dLen uint64)
type gcmAsm struct {
gcm
bytesProductTable [256]byte
}
// NewGCM returns the SM4 cipher wrapped in Galois Counter Mode. This is only
// called by crypto/cipher.NewGCM via the gcmAble interface.
func (c *sm4CipherGCM) NewGCM(nonceSize, tagSize int) (cipher.AEAD, error) {
g := &gcmAsm{}
g.cipher = c.sm4CipherAsm
g.nonceSize = nonceSize
g.tagSize = tagSize
gcmSm4Init(&g.bytesProductTable, g.cipher.enc, INST_AES)
return g, nil
}
func (g *gcmAsm) NonceSize() int {
return g.nonceSize
}
func (g *gcmAsm) Overhead() int {
return g.tagSize
}
// Seal encrypts and authenticates plaintext. See the cipher.AEAD interface for
// details.
func (g *gcmAsm) Seal(dst, nonce, plaintext, data []byte) []byte {
if len(nonce) != g.nonceSize {
panic("cipher: incorrect nonce length given to GCM")
}
if uint64(len(plaintext)) > ((1<<32)-2)*BlockSize {
panic("cipher: message too large for GCM")
}
var counter, tagMask [gcmBlockSize]byte
if len(nonce) == gcmStandardNonceSize {
// Init counter to nonce||1
copy(counter[:], nonce)
counter[gcmBlockSize-1] = 1
} else {
// Otherwise counter = GHASH(nonce)
gcmSm4Data(&g.bytesProductTable, nonce, &counter)
gcmSm4Finish(&g.bytesProductTable, &tagMask, &counter, uint64(len(nonce)), uint64(0))
}
g.cipher.Encrypt(tagMask[:], counter[:])
var tagOut [gcmTagSize]byte
gcmSm4Data(&g.bytesProductTable, data, &tagOut)
ret, out := alias.SliceForAppend(dst, len(plaintext)+g.tagSize)
if alias.InexactOverlap(out[:len(plaintext)], plaintext) {
panic("cipher: invalid buffer overlap")
}
if len(plaintext) > 0 {
gcmSm4Enc(&g.bytesProductTable, out, plaintext, &counter, &tagOut, g.cipher.enc)
}
gcmSm4Finish(&g.bytesProductTable, &tagMask, &tagOut, uint64(len(plaintext)), uint64(len(data)))
copy(out[len(plaintext):], tagOut[:])
return ret
}
// Open authenticates and decrypts ciphertext. See the cipher.AEAD interface
// for details.
func (g *gcmAsm) Open(dst, nonce, ciphertext, data []byte) ([]byte, error) {
if len(nonce) != g.nonceSize {
panic("cipher: incorrect nonce length given to GCM")
}
// Sanity check to prevent the authentication from always succeeding if an implementation
// leaves tagSize uninitialized, for example.
if g.tagSize < gcmMinimumTagSize {
panic("cipher: incorrect GCM tag size")
}
if len(ciphertext) < g.tagSize {
return nil, errOpen
}
if uint64(len(ciphertext)) > ((1<<32)-2)*uint64(BlockSize)+uint64(g.tagSize) {
return nil, errOpen
}
tag := ciphertext[len(ciphertext)-g.tagSize:]
ciphertext = ciphertext[:len(ciphertext)-g.tagSize]
// See GCM spec, section 7.1.
var counter, tagMask [gcmBlockSize]byte
if len(nonce) == gcmStandardNonceSize {
// Init counter to nonce||1
copy(counter[:], nonce)
counter[gcmBlockSize-1] = 1
} else {
// Otherwise counter = GHASH(nonce)
gcmSm4Data(&g.bytesProductTable, nonce, &counter)
gcmSm4Finish(&g.bytesProductTable, &tagMask, &counter, uint64(len(nonce)), uint64(0))
}
g.cipher.Encrypt(tagMask[:], counter[:])
var expectedTag [gcmTagSize]byte
gcmSm4Data(&g.bytesProductTable, data, &expectedTag)
ret, out := alias.SliceForAppend(dst, len(ciphertext))
if alias.InexactOverlap(out, ciphertext) {
panic("cipher: invalid buffer overlap")
}
if len(ciphertext) > 0 {
gcmSm4Dec(&g.bytesProductTable, out, ciphertext, &counter, &expectedTag, g.cipher.enc)
}
gcmSm4Finish(&g.bytesProductTable, &tagMask, &expectedTag, uint64(len(ciphertext)), uint64(len(data)))
if subtle.ConstantTimeCompare(expectedTag[:g.tagSize], tag) != 1 {
for i := range out {
out[i] = 0
}
return nil, errOpen
}
return ret, nil
}