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#include "os.h"
#include <libsec.h>
/* little-endian data order */
#define GET4(p) ((p)[0]|((p)[1]<<8)|((p)[2]<<16)|((p)[3]<<24))
#define PUT4(p,v) (p)[0]=(v);(p)[1]=(v)>>8;(p)[2]=(v)>>16;(p)[3]=(v)>>24
static void
gf_mulx(uchar *x)
{
ulong t0, t1, t2, t3, t4;
t0 = GET4(x);
t1 = GET4(x+4);
t2 = GET4(x+8);
t3 = GET4(x+12);
t4 = (t3 >> 31);
t3 = (t3 << 1) | (t2 >> 31);
t2 = (t2 << 1) | (t1 >> 31);
t1 = (t1 << 1) | (t0 >> 31);
t0 = (t0 << 1) ^ (t4*135);
PUT4(x, t0);
PUT4(x+4, t1);
PUT4(x+8, t2);
PUT4(x+12, t3);
}
static void
xor128(uchar *o, uchar *i1, uchar *i2)
{
int i;
for(i=0; i<16; i++)
o[i] = i1[i] ^ i2[i];
}
static void
setupT(AESstate *tweak, uvlong sectorNumber, uchar T[AESbsize])
{
PUT4(T+0, (ulong)sectorNumber), sectorNumber >>= 32;
PUT4(T+4, (ulong)sectorNumber);
PUT4(T+8, 0);
PUT4(T+12, 0);
aes_encrypt(tweak->ekey, tweak->rounds, T, T);
}
void
aes_xts_encrypt(AESstate *tweak, AESstate *ecb,
uvlong sectorNumber, uchar *input, uchar *output, ulong len)
{
uchar T[AESbsize], x[AESbsize];
if(len % AESbsize)
abort();
setupT(tweak, sectorNumber, T);
for (; len > 0; len -= AESbsize, input += AESbsize, output += AESbsize) {
xor128(x, input, T);
aes_encrypt(ecb->ekey, ecb->rounds, x, x);
xor128(output, x, T);
gf_mulx(T);
}
}
void
aes_xts_decrypt(AESstate *tweak, AESstate *ecb,
uvlong sectorNumber, uchar *input, uchar *output, ulong len)
{
uchar T[AESbsize], x[AESbsize];
if(len % AESbsize)
abort();
setupT(tweak, sectorNumber, T);
for (; len > 0; len -= AESbsize, input += AESbsize, output += AESbsize) {
xor128(x, input, T);
aes_decrypt(ecb->dkey, ecb->rounds, x, x);
xor128(output, x, T);
gf_mulx(T);
}
}
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