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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200
|
// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// The C code in this file was pulled from Appendix A of RFC 4493 and modified
// by Aaron Jacobs, adding an implementation of the missing AES_128 function
// that uses OpenSSL and changing the formatting slightly. These modifications
// and the Go code are copyright Aaron Jacobs.
package main
/*
#cgo CFLAGS: -Wno-deprecated-declarations
#cgo LDFLAGS: -lcrypto
#include <assert.h>
#include <openssl/aes.h>
#include <stdlib.h>
unsigned char const_Rb[16] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x87
};
unsigned char const_Zero[16] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
void AES_128(const unsigned char *key, const unsigned char *in, unsigned char *out) {
AES_KEY key_struct;
assert(AES_set_encrypt_key(key, 128, &key_struct) == 0);
AES_encrypt(in, out, &key_struct);
}
void xor_128(unsigned char *a, unsigned char *b, unsigned char *out)
{
int i;
for (i=0;i<16; i++)
{
out[i] = a[i] ^ b[i];
}
}
void leftshift_onebit(unsigned char *input,unsigned char *output)
{
int i;
unsigned char overflow = 0;
for ( i=15; i>=0; i-- ) {
output[i] = input[i] << 1;
output[i] |= overflow;
overflow = (input[i] & 0x80)?1:0;
}
return;
}
void generate_subkey(unsigned char *key, unsigned char *K1, unsigned
char *K2)
{
unsigned char L[16];
unsigned char Z[16];
unsigned char tmp[16];
int i;
for ( i=0; i<16; i++ ) Z[i] = 0;
AES_128(key,Z,L);
if ( (L[0] & 0x80) == 0 ) {
leftshift_onebit(L,K1);
} else {
leftshift_onebit(L,tmp);
xor_128(tmp,const_Rb,K1);
}
if ( (K1[0] & 0x80) == 0 ) {
leftshift_onebit(K1,K2);
} else {
leftshift_onebit(K1,tmp);
xor_128(tmp,const_Rb,K2);
}
return;
}
void padding ( unsigned char *lastb, unsigned char *pad, int length )
{
int j;
for ( j=0; j<16; j++ ) {
if ( j < length ) {
pad[j] = lastb[j];
} else if ( j == length ) {
pad[j] = 0x80;
} else {
pad[j] = 0x00;
}
}
}
void AES_CMAC ( unsigned char *key, unsigned char *input, int length,
unsigned char *mac )
{
unsigned char X[16],Y[16], M_last[16], padded[16];
unsigned char K1[16], K2[16];
int n, i, flag;
generate_subkey(key,K1,K2);
n = (length+15) / 16;
if ( n == 0 ) {
n = 1;
flag = 0;
} else {
if ( (length%16) == 0 ) {
flag = 1;
} else {
flag = 0;
}
}
if ( flag ) {
xor_128(&input[16*(n-1)],K1,M_last);
} else {
padding(&input[16*(n-1)],padded,length%16);
xor_128(padded,K2,M_last);
}
for ( i=0; i<16; i++ ) X[i] = 0;
for ( i=0; i<n-1; i++ ) {
xor_128(X,&input[16*i],Y);
AES_128(key,Y,X);
}
xor_128(X,M_last,Y);
AES_128(key,Y,X);
for ( i=0; i<16; i++ ) {
mac[i] = X[i];
}
}
*/
import "C"
import (
"unsafe"
)
func generateSubkey(key []byte) (k1 []byte, k2 []byte) {
if len(key) != 16 {
panic("Invalid length.")
}
cK1 := (*C.uchar)(C.malloc(16))
defer C.free(unsafe.Pointer(cK1))
cK2 := (*C.uchar)(C.malloc(16))
defer C.free(unsafe.Pointer(cK2))
C.generate_subkey((*C.uchar)(&key[0]), cK1, cK2)
return C.GoBytes(unsafe.Pointer(cK1), 16), C.GoBytes(unsafe.Pointer(cK2), 16)
}
func generateCmac(key []byte, msg []byte) []byte {
if len(key) != 16 {
panic("Invalid length.")
}
cMac := (*C.uchar)(C.malloc(16))
defer C.free(unsafe.Pointer(cMac))
var msgStart *C.uchar
if len(msg) > 0 {
msgStart = (*C.uchar)(&msg[0])
} else {
// Avoid indexing into empty slice/C array.
msgStart = (*C.uchar)(C.malloc(1))
defer C.free(unsafe.Pointer(msgStart))
}
C.AES_CMAC(
(*C.uchar)(&key[0]),
msgStart,
C.int(len(msg)),
cMac)
return C.GoBytes(unsafe.Pointer(cMac), 16)
}
|