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
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
// Copyright 2009 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.
// This Go implementation is derived in part from the reference
// ANSI C implementation, which carries the following notice:
//
// rijndael-alg-fst.c
//
// @version 3.0 (December 2000)
//
// Optimised ANSI C code for the Rijndael cipher (now AES)
//
// @author Vincent Rijmen <vincent.rijmen@esat.kuleuven.ac.be>
// @author Antoon Bosselaers <antoon.bosselaers@esat.kuleuven.ac.be>
// @author Paulo Barreto <paulo.barreto@terra.com.br>
//
// This code is hereby placed in the public domain.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
// OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
// OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
// EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// See FIPS 197 for specification, and see Daemen and Rijmen's Rijndael submission
// for implementation details.
// http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf
// http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf
package aes
// Encrypt one block from src into dst, using the expanded key xk.
func encryptBlock(xk []uint32, dst, src []byte) {
var s0, s1, s2, s3, t0, t1, t2, t3 uint32
s0 = uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3])
s1 = uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7])
s2 = uint32(src[8])<<24 | uint32(src[9])<<16 | uint32(src[10])<<8 | uint32(src[11])
s3 = uint32(src[12])<<24 | uint32(src[13])<<16 | uint32(src[14])<<8 | uint32(src[15])
// First round just XORs input with key.
s0 ^= xk[0]
s1 ^= xk[1]
s2 ^= xk[2]
s3 ^= xk[3]
// Middle rounds shuffle using tables.
// Number of rounds is set by length of expanded key.
nr := len(xk)/4 - 2 // - 2: one above, one more below
k := 4
for r := 0; r < nr; r++ {
t0 = xk[k+0] ^ te[0][s0>>24] ^ te[1][s1>>16&0xff] ^ te[2][s2>>8&0xff] ^ te[3][s3&0xff]
t1 = xk[k+1] ^ te[0][s1>>24] ^ te[1][s2>>16&0xff] ^ te[2][s3>>8&0xff] ^ te[3][s0&0xff]
t2 = xk[k+2] ^ te[0][s2>>24] ^ te[1][s3>>16&0xff] ^ te[2][s0>>8&0xff] ^ te[3][s1&0xff]
t3 = xk[k+3] ^ te[0][s3>>24] ^ te[1][s0>>16&0xff] ^ te[2][s1>>8&0xff] ^ te[3][s2&0xff]
k += 4
s0, s1, s2, s3 = t0, t1, t2, t3
}
// Last round uses s-box directly and XORs to produce output.
s0 = uint32(sbox0[t0>>24])<<24 | uint32(sbox0[t1>>16&0xff])<<16 | uint32(sbox0[t2>>8&0xff])<<8 | uint32(sbox0[t3&0xff])
s1 = uint32(sbox0[t1>>24])<<24 | uint32(sbox0[t2>>16&0xff])<<16 | uint32(sbox0[t3>>8&0xff])<<8 | uint32(sbox0[t0&0xff])
s2 = uint32(sbox0[t2>>24])<<24 | uint32(sbox0[t3>>16&0xff])<<16 | uint32(sbox0[t0>>8&0xff])<<8 | uint32(sbox0[t1&0xff])
s3 = uint32(sbox0[t3>>24])<<24 | uint32(sbox0[t0>>16&0xff])<<16 | uint32(sbox0[t1>>8&0xff])<<8 | uint32(sbox0[t2&0xff])
s0 ^= xk[k+0]
s1 ^= xk[k+1]
s2 ^= xk[k+2]
s3 ^= xk[k+3]
dst[0], dst[1], dst[2], dst[3] = byte(s0>>24), byte(s0>>16), byte(s0>>8), byte(s0)
dst[4], dst[5], dst[6], dst[7] = byte(s1>>24), byte(s1>>16), byte(s1>>8), byte(s1)
dst[8], dst[9], dst[10], dst[11] = byte(s2>>24), byte(s2>>16), byte(s2>>8), byte(s2)
dst[12], dst[13], dst[14], dst[15] = byte(s3>>24), byte(s3>>16), byte(s3>>8), byte(s3)
}
// Decrypt one block from src into dst, using the expanded key xk.
func decryptBlock(xk []uint32, dst, src []byte) {
var s0, s1, s2, s3, t0, t1, t2, t3 uint32
s0 = uint32(src[0])<<24 | uint32(src[1])<<16 | uint32(src[2])<<8 | uint32(src[3])
s1 = uint32(src[4])<<24 | uint32(src[5])<<16 | uint32(src[6])<<8 | uint32(src[7])
s2 = uint32(src[8])<<24 | uint32(src[9])<<16 | uint32(src[10])<<8 | uint32(src[11])
s3 = uint32(src[12])<<24 | uint32(src[13])<<16 | uint32(src[14])<<8 | uint32(src[15])
// First round just XORs input with key.
s0 ^= xk[0]
s1 ^= xk[1]
s2 ^= xk[2]
s3 ^= xk[3]
// Middle rounds shuffle using tables.
// Number of rounds is set by length of expanded key.
nr := len(xk)/4 - 2 // - 2: one above, one more below
k := 4
for r := 0; r < nr; r++ {
t0 = xk[k+0] ^ td[0][s0>>24] ^ td[1][s3>>16&0xff] ^ td[2][s2>>8&0xff] ^ td[3][s1&0xff]
t1 = xk[k+1] ^ td[0][s1>>24] ^ td[1][s0>>16&0xff] ^ td[2][s3>>8&0xff] ^ td[3][s2&0xff]
t2 = xk[k+2] ^ td[0][s2>>24] ^ td[1][s1>>16&0xff] ^ td[2][s0>>8&0xff] ^ td[3][s3&0xff]
t3 = xk[k+3] ^ td[0][s3>>24] ^ td[1][s2>>16&0xff] ^ td[2][s1>>8&0xff] ^ td[3][s0&0xff]
k += 4
s0, s1, s2, s3 = t0, t1, t2, t3
}
// Last round uses s-box directly and XORs to produce output.
s0 = uint32(sbox1[t0>>24])<<24 | uint32(sbox1[t3>>16&0xff])<<16 | uint32(sbox1[t2>>8&0xff])<<8 | uint32(sbox1[t1&0xff])
s1 = uint32(sbox1[t1>>24])<<24 | uint32(sbox1[t0>>16&0xff])<<16 | uint32(sbox1[t3>>8&0xff])<<8 | uint32(sbox1[t2&0xff])
s2 = uint32(sbox1[t2>>24])<<24 | uint32(sbox1[t1>>16&0xff])<<16 | uint32(sbox1[t0>>8&0xff])<<8 | uint32(sbox1[t3&0xff])
s3 = uint32(sbox1[t3>>24])<<24 | uint32(sbox1[t2>>16&0xff])<<16 | uint32(sbox1[t1>>8&0xff])<<8 | uint32(sbox1[t0&0xff])
s0 ^= xk[k+0]
s1 ^= xk[k+1]
s2 ^= xk[k+2]
s3 ^= xk[k+3]
dst[0], dst[1], dst[2], dst[3] = byte(s0>>24), byte(s0>>16), byte(s0>>8), byte(s0)
dst[4], dst[5], dst[6], dst[7] = byte(s1>>24), byte(s1>>16), byte(s1>>8), byte(s1)
dst[8], dst[9], dst[10], dst[11] = byte(s2>>24), byte(s2>>16), byte(s2>>8), byte(s2)
dst[12], dst[13], dst[14], dst[15] = byte(s3>>24), byte(s3>>16), byte(s3>>8), byte(s3)
}
// Apply sbox0 to each byte in w.
func subw(w uint32) uint32 {
return uint32(sbox0[w>>24])<<24 |
uint32(sbox0[w>>16&0xff])<<16 |
uint32(sbox0[w>>8&0xff])<<8 |
uint32(sbox0[w&0xff])
}
// Rotate
func rotw(w uint32) uint32 { return w<<8 | w>>24 }
// Key expansion algorithm. See FIPS-197, Figure 11.
// Their rcon[i] is our powx[i-1] << 24.
func expandKey(key []byte, enc, dec []uint32) {
// Encryption key setup.
var i int
nk := len(key) / 4
for i = 0; i < nk; i++ {
enc[i] = uint32(key[4*i])<<24 | uint32(key[4*i+1])<<16 | uint32(key[4*i+2])<<8 | uint32(key[4*i+3])
}
for ; i < len(enc); i++ {
t := enc[i-1]
if i%nk == 0 {
t = subw(rotw(t)) ^ (uint32(powx[i/nk-1]) << 24)
} else if nk > 6 && i%nk == 4 {
t = subw(t)
}
enc[i] = enc[i-nk] ^ t
}
// Derive decryption key from encryption key.
// Reverse the 4-word round key sets from enc to produce dec.
// All sets but the first and last get the MixColumn transform applied.
if dec == nil {
return
}
n := len(enc)
for i := 0; i < n; i += 4 {
ei := n - i - 4
for j := 0; j < 4; j++ {
x := enc[ei+j]
if i > 0 && i+4 < n {
x = td[0][sbox0[x>>24]] ^ td[1][sbox0[x>>16&0xff]] ^ td[2][sbox0[x>>8&0xff]] ^ td[3][sbox0[x&0xff]]
}
dec[i+j] = x
}
}
}
|
