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crypto: drbg - use crypto_inc
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The DRBG internal buffer addition function is replaced with crypto_inc when
a buffer is to be incremented by one.

The function drbg_add_buf is moved to the CONFIG_CRYPTO_DRBG_HASH ifdef
area as it is now only needed for the Hash DRBG.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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@smuellerDD @herbertx
smuellerDD authored and herbertx committed Oct 24, 2014
1 parent 3e8cffd commit 41a8498
Showing 1 changed file with 38 additions and 41 deletions.
79 changes: 38 additions & 41 deletions crypto/drbg.c
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Original file line number Diff line number Diff line change
Expand Up @@ -283,38 +283,6 @@ static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)

conversion->conv = cpu_to_be32(val);
}

/*
* Increment buffer
*
* @dst buffer to increment
* @add value to add
*/
static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
const unsigned char *add, size_t addlen)
{
/* implied: dstlen > addlen */
unsigned char *dstptr;
const unsigned char *addptr;
unsigned int remainder = 0;
size_t len = addlen;

dstptr = dst + (dstlen-1);
addptr = add + (addlen-1);
while (len) {
remainder += *dstptr + *addptr;
*dstptr = remainder & 0xff;
remainder >>= 8;
len--; dstptr--; addptr--;
}
len = dstlen - addlen;
while (len && remainder > 0) {
remainder = *dstptr + 1;
*dstptr = remainder & 0xff;
remainder >>= 8;
len--; dstptr--;
}
}
#endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */

/******************************************************************
Expand Down Expand Up @@ -554,7 +522,6 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */
unsigned int len = 0;
struct drbg_string cipherin;
unsigned char prefix = DRBG_PREFIX1;

memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
if (3 > reseed)
Expand All @@ -574,7 +541,7 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
*/
while (len < (drbg_statelen(drbg))) {
/* 10.2.1.2 step 2.1 */
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
crypto_inc(drbg->V, drbg_blocklen(drbg));
/*
* 10.2.1.2 step 2.2 */
ret = drbg_kcapi_sym(drbg, drbg->C, temp + len, &cipherin);
Expand Down Expand Up @@ -617,7 +584,6 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
int len = 0;
int ret = 0;
struct drbg_string data;
unsigned char prefix = DRBG_PREFIX1;

memset(drbg->scratchpad, 0, drbg_blocklen(drbg));

Expand All @@ -629,7 +595,7 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
}

/* 10.2.1.5.2 step 4.1 */
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
crypto_inc(drbg->V, drbg_blocklen(drbg));
drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg));
while (len < buflen) {
int outlen = 0;
Expand All @@ -643,15 +609,15 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
drbg_blocklen(drbg) : (buflen - len);
if (!drbg_fips_continuous_test(drbg, drbg->scratchpad)) {
/* 10.2.1.5.2 step 6 */
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
crypto_inc(drbg->V, drbg_blocklen(drbg));
continue;
}
/* 10.2.1.5.2 step 4.3 */
memcpy(buf + len, drbg->scratchpad, outlen);
len += outlen;
/* 10.2.1.5.2 step 6 */
if (len < buflen)
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
crypto_inc(drbg->V, drbg_blocklen(drbg));
}

/* 10.2.1.5.2 step 6 */
Expand Down Expand Up @@ -796,6 +762,38 @@ static struct drbg_state_ops drbg_hmac_ops = {

#ifdef CONFIG_CRYPTO_DRBG_HASH
#define CRYPTO_DRBG_HASH_STRING "HASH "
/*
* Increment buffer
*
* @dst buffer to increment
* @add value to add
*/
static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
const unsigned char *add, size_t addlen)
{
/* implied: dstlen > addlen */
unsigned char *dstptr;
const unsigned char *addptr;
unsigned int remainder = 0;
size_t len = addlen;

dstptr = dst + (dstlen-1);
addptr = add + (addlen-1);
while (len) {
remainder += *dstptr + *addptr;
*dstptr = remainder & 0xff;
remainder >>= 8;
len--; dstptr--; addptr--;
}
len = dstlen - addlen;
while (len && remainder > 0) {
remainder = *dstptr + 1;
*dstptr = remainder & 0xff;
remainder >>= 8;
len--; dstptr--;
}
}

/*
* scratchpad usage: as drbg_hash_update and drbg_hash_df are used
* interlinked, the scratchpad is used as follows:
Expand Down Expand Up @@ -942,7 +940,6 @@ static int drbg_hash_hashgen(struct drbg_state *drbg,
unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
struct drbg_string data;
LIST_HEAD(datalist);
unsigned char prefix = DRBG_PREFIX1;

memset(src, 0, drbg_statelen(drbg));
memset(dst, 0, drbg_blocklen(drbg));
Expand All @@ -963,15 +960,15 @@ static int drbg_hash_hashgen(struct drbg_state *drbg,
outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
drbg_blocklen(drbg) : (buflen - len);
if (!drbg_fips_continuous_test(drbg, dst)) {
drbg_add_buf(src, drbg_statelen(drbg), &prefix, 1);
crypto_inc(src, drbg_statelen(drbg));
continue;
}
/* 10.1.1.4 step hashgen 4.2 */
memcpy(buf + len, dst, outlen);
len += outlen;
/* 10.1.1.4 hashgen step 4.3 */
if (len < buflen)
drbg_add_buf(src, drbg_statelen(drbg), &prefix, 1);
crypto_inc(src, drbg_statelen(drbg));
}

out:
Expand Down

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