diff options
| -rw-r--r-- | crypto/drbg.c | 41 |
1 files changed, 22 insertions, 19 deletions
diff --git a/crypto/drbg.c b/crypto/drbg.c index c9b4c4906d9b..dba5ed2f83b6 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -562,7 +562,21 @@ out: return ret; } -/* update function of CTR DRBG as defined in 10.2.1.2 */ +/* + * update function of CTR DRBG as defined in 10.2.1.2 + * + * The reseed variable has an enhanced meaning compared to the update + * functions of the other DRBGs as follows: + * 0 => initial seed from initialization + * 1 => reseed via drbg_seed + * 2 => first invocation from drbg_ctr_update when addtl is present. In + * this case, the df_data scratchpad is not deleted so that it is + * available for another calls to prevent calling the DF function + * again. + * 3 => second invocation from drbg_ctr_update. When the update function + * was called with addtl, the df_data memory already contains the + * DFed addtl information and we do not need to call DF again. + */ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, int reseed) { @@ -577,7 +591,8 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, unsigned char prefix = DRBG_PREFIX1; memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg)); - memset(df_data, 0, drbg_statelen(drbg)); + if (3 > reseed) + memset(df_data, 0, drbg_statelen(drbg)); /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */ if (seed) { @@ -619,7 +634,8 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, out: memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg)); - memset(df_data, 0, drbg_statelen(drbg)); + if (2 != reseed) + memset(df_data, 0, drbg_statelen(drbg)); return ret; } @@ -644,7 +660,7 @@ static int drbg_ctr_generate(struct drbg_state *drbg, LIST_HEAD(addtllist); list_add_tail(&addtl->list, &addtllist); - ret = drbg_ctr_update(drbg, &addtllist, 1); + ret = drbg_ctr_update(drbg, &addtllist, 2); if (ret) return 0; } @@ -675,21 +691,8 @@ static int drbg_ctr_generate(struct drbg_state *drbg, drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1); } - /* - * 10.2.1.5.2 step 6 - * The following call invokes the DF function again which could be - * optimized. In step 2, the "additional_input" after step 2 is the - * output of the DF function. If this result would be saved, the DF - * function would not need to be invoked again at this point. - */ - if (addtl && 0 < addtl->len) { - LIST_HEAD(addtllist); - - list_add_tail(&addtl->list, &addtllist); - ret = drbg_ctr_update(drbg, &addtllist, 1); - } else { - ret = drbg_ctr_update(drbg, NULL, 1); - } + /* 10.2.1.5.2 step 6 */ + ret = drbg_ctr_update(drbg, NULL, 3); if (ret) len = ret; |
