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crypto: drbg - use full CTR AES for update

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The CTR DRBG update function performs a full CTR AES operation including
the XOR with "plaintext" data. Hence, remove the XOR from the code and
use the CTR mode to do the XOR.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Mueller 2016-06-14 07:35:37 +02:00 committed by Herbert Xu
parent 3cfc3b9721
commit a07203fbfc
1 changed files with 13 additions and 17 deletions
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30
crypto/drbg.c
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@ -258,7 +258,10 @@ static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
const struct drbg_string *in);
static int drbg_init_sym_kernel(struct drbg_state *drbg);
static int drbg_fini_sym_kernel(struct drbg_state *drbg);
static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *outbuf, u32 outlen);
static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
u8 *inbuf, u32 inbuflen,
u8 *outbuf, u32 outlen);
#define DRBG_CTR_NULL_LEN 128
/* BCC function for CTR DRBG as defined in 10.4.3 */
static int drbg_ctr_bcc(struct drbg_state *drbg,
@ -481,8 +484,6 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
unsigned char *temp = drbg->scratchpad;
unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
drbg_blocklen(drbg);
unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */
unsigned int len = 0;
if (3 > reseed)
memset(df_data, 0, drbg_statelen(drbg));
@ -510,18 +511,11 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
goto out;
}
ret = drbg_kcapi_sym_ctr(drbg, temp, drbg_statelen(drbg));
ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
temp, drbg_statelen(drbg));
if (ret)
return ret;
/* 10.2.1.2 step 4 */
temp_p = temp;
df_data_p = df_data;
for (len = 0; len < drbg_statelen(drbg); len++) {
*temp_p ^= *df_data_p;
df_data_p++; temp_p++;
}
/* 10.2.1.2 step 5 */
memcpy(drbg->C, temp, drbg_keylen(drbg));
ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
@ -561,7 +555,8 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
}
/* 10.2.1.5.2 step 4.1 */
ret = drbg_kcapi_sym_ctr(drbg, buf, len);
ret = drbg_kcapi_sym_ctr(drbg, drbg->ctr_null_value, DRBG_CTR_NULL_LEN,
buf, len);
if (ret)
return ret;
@ -1657,7 +1652,6 @@ static void drbg_skcipher_cb(struct crypto_async_request *req, int error)
complete(&drbg->ctr_completion);
}
#define DRBG_CTR_NULL_LEN 128
static int drbg_init_sym_kernel(struct drbg_state *drbg)
{
struct crypto_cipher *tfm;
@ -1733,14 +1727,16 @@ static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
return 0;
}
static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *outbuf, u32 outlen)
static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
u8 *inbuf, u32 inlen,
u8 *outbuf, u32 outlen)
{
struct scatterlist sg_in;
sg_init_one(&sg_in, drbg->ctr_null_value, DRBG_CTR_NULL_LEN);
sg_init_one(&sg_in, inbuf, inlen);
while (outlen) {
u32 cryptlen = min_t(u32, outlen, DRBG_CTR_NULL_LEN);
u32 cryptlen = min_t(u32, inlen, outlen);
struct scatterlist sg_out;
int ret;