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optimize LRW

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This commit is contained in:
Vladimir 'phcoder' Serbinenko 2011-04-23 16:41:43 +02:00
parent 6fd80b9ac4
commit 6f33a8eebc
1 changed files with 89 additions and 25 deletions
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114
grub-core/disk/luks.c
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@ -108,6 +108,7 @@ struct grub_luks
enum grub_disk_dev_id source_dev_id;
char uuid[sizeof (((struct grub_luks_phdr *) 0)->uuid) + 1];
grub_uint8_t lrw_key[GF_SIZE / 8];
grub_uint8_t *lrw_precalc;
#ifdef GRUB_UTIL
char *cheat;
int cheat_fd;
@ -203,6 +204,68 @@ grub_crypto_pcbc_decrypt (grub_crypto_cipher_handle_t cipher,
return GPG_ERR_NO_ERROR;
}
#define GF_BYTES (GF_SIZE / 8)
#define GF_PER_SECTOR (GRUB_DISK_SECTOR_SIZE / GF_BYTES)
struct lrw_sector
{
grub_uint8_t low[GF_BYTES];
grub_uint8_t high[GF_BYTES];
grub_uint8_t low_byte, low_byte_c;
};
static void
generate_lrw_sector (struct lrw_sector *sec,
const struct grub_luks *dev,
const grub_uint8_t *iv)
{
grub_uint8_t idx[GF_BYTES];
grub_uint16_t c;
int j;
grub_memcpy (idx, iv, GF_BYTES);
sec->low_byte = (idx[GF_BYTES - 1] & (GF_PER_SECTOR - 1));
sec->low_byte_c = (((GF_PER_SECTOR - 1) & ~sec->low_byte) + 1);
idx[GF_BYTES - 1] &= ~(GF_PER_SECTOR - 1);
gf_mul_be (sec->low, dev->lrw_key, idx);
if (!sec->low_byte)
return;
c = idx[GF_BYTES - 1] + GF_PER_SECTOR;
if (c & 0x100)
{
for (j = GF_BYTES - 2; j >= 0; j--)
{
idx[j]++;
if (idx[j] != 0)
break;
}
}
idx[GF_BYTES - 1] = c;
gf_mul_be (sec->high, dev->lrw_key, idx);
}
static void __attribute__ ((unused))
lrw_xor (const struct lrw_sector *sec,
const struct grub_luks *dev,
grub_uint8_t *b)
{
int i;
for (i = 0; i < sec->low_byte_c * GF_BYTES; i += GF_BYTES)
grub_crypto_xor (b + i, b + i, sec->low, GF_BYTES);
grub_crypto_xor (b, b, dev->lrw_precalc + GF_BYTES * sec->low_byte,
sec->low_byte_c * GF_BYTES);
if (!sec->low_byte)
return;
for (i = sec->low_byte_c * GF_BYTES;
i < GRUB_DISK_SECTOR_SIZE; i += GF_BYTES)
grub_crypto_xor (b + i, b + i, sec->high, GF_BYTES);
grub_crypto_xor (b + sec->low_byte_c * GF_BYTES,
b + sec->low_byte_c * GF_BYTES,
dev->lrw_precalc, sec->low_byte * GF_BYTES);
}
static gcry_err_code_t
luks_decrypt (const struct grub_luks *dev,
grub_uint8_t * data, grub_size_t len, grub_disk_addr_t sector)
@ -287,30 +350,16 @@ luks_decrypt (const struct grub_luks *dev,
break;
case GRUB_LUKS_MODE_LRW:
{
int j, k;
for (j = 0;
j < GRUB_DISK_SECTOR_SIZE;
j += dev->cipher->cipher->blocksize)
{
grub_uint8_t x[sz * sizeof (grub_uint32_t)];
struct lrw_sector sec;
gf_mul_be (x, dev->lrw_key, (grub_uint8_t *) iv);
grub_crypto_xor (data + i + j, data + i + j, x,
dev->cipher->cipher->blocksize);
err = grub_crypto_ecb_decrypt (dev->cipher, data + i + j,
data + i + j,
dev->cipher->cipher->blocksize);
if (err)
return err;
grub_crypto_xor (data + i + j, data + i + j, x,
dev->cipher->cipher->blocksize);
for (k = sz - 1; k >= 0; k++)
{
iv[k] = grub_cpu_to_be32 (grub_be_to_cpu32 (iv[k]) + 1);
if (iv[k] != 0)
break;
}
}
generate_lrw_sector (&sec, dev, (grub_uint8_t *) iv);
lrw_xor (&sec, dev, data + i);
err = grub_crypto_ecb_decrypt (dev->cipher, data + i,
data + i, GRUB_DISK_SECTOR_SIZE);
if (err)
return err;
lrw_xor (&sec, dev, data + i);
}
break;
default:
@ -576,8 +625,23 @@ luks_setkey (grub_luks_t dev, grub_uint8_t *key, grub_size_t keysize)
}
if (dev->mode == GRUB_LUKS_MODE_LRW)
grub_memcpy (dev->lrw_key, key + real_keysize,
dev->cipher->cipher->blocksize);
{
int i;
grub_uint8_t idx[GF_SIZE / 8];
grub_free (dev->lrw_precalc);
grub_memcpy (dev->lrw_key, key + real_keysize,
dev->cipher->cipher->blocksize);
dev->lrw_precalc = grub_malloc (GRUB_DISK_SECTOR_SIZE);
if (!dev->lrw_precalc)
return GPG_ERR_OUT_OF_MEMORY;
grub_memset (idx, 0, GF_SIZE / 8);
for (i = 0; i < GRUB_DISK_SECTOR_SIZE; i += GF_SIZE / 8)
{
idx[15] = i / (GF_SIZE / 8);
gf_mul_be (dev->lrw_precalc + i, idx, dev->lrw_key);
}
}
return GPG_ERR_NO_ERROR;
}