1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <string.h>
4 #include <assert.h>
5 #include "aes_core.h"
6
rk_crypto_ofb128_encrypt(const unsigned char * in,unsigned char * out,int len,const void * key,unsigned char * ivec,unsigned int * num)7 static void rk_crypto_ofb128_encrypt(const unsigned char *in, unsigned char *out,
8 int len, const void *key, unsigned char *ivec, unsigned int *num)
9 {
10 int n, l=0;
11
12 n = *num;
13
14 while (l < len) {
15 if (n==0) {
16 rk_aes_encrypt(ivec, ivec, key);
17 }
18 out[l] = in[l] ^ ivec[n];
19 ++l;
20 n = (n+1) % 16;
21 }
22
23 *num=n;
24 }
25
26 /* XTS makes use of two different keys, usually generated by splitting
27 * the supplied block cipher's key in half.
28 * Because of the splitting, users wanting AES 256 and AES 128 encryption
29 * will need to choose key sizes of 512 bits and 256 bits respectively.
30 */
rk_aes_ofb_encrypt(const unsigned char * in,unsigned char * out,unsigned long length,const unsigned char * key,const int key_len,unsigned char * ivec,const int enc)31 int rk_aes_ofb_encrypt(const unsigned char *in, unsigned char *out,
32 unsigned long length, const unsigned char *key, const int key_len,
33 unsigned char *ivec, const int enc)
34 {
35 RK_AES_KEY ks;
36 unsigned int num = 0;
37
38 if(key_len != 16 && key_len != 24 && key_len != 32)
39 return -1;
40
41 if(length == 0)
42 return -1;
43
44 rk_aes_set_encrypt_key(key, key_len * 8, &ks);
45 rk_crypto_ofb128_encrypt(in, out, length, &ks, ivec, &num);
46 return 0;
47 }
48
49
50