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Add continuous block test to Hash DRBG

This commit is contained in:
John Safranek 2014-10-23 14:07:31 -07:00
parent e35e02a283
commit 4d7f26af8d
1 changed files with 39 additions and 6 deletions
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45
ctaocrypt/src/random.c
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@ -107,6 +107,8 @@ typedef struct DRBG {
byte V[DRBG_SEED_LEN];
byte C[DRBG_SEED_LEN];
word32 reseedCtr;
word32 lastBlock;
byte matchCount;
} DRBG;
@ -187,6 +189,8 @@ static int Hash_DRBG_Reseed(DRBG* drbg, const byte* entropy, word32 entropySz)
}
drbg->reseedCtr = 1;
drbg->lastBlock = 0;
drbg->matchCount = 0;
return DRBG_SUCCESS;
}
@ -207,8 +211,15 @@ static int Hash_gen(DRBG* drbg, byte* out, word32 outSz, const byte* V)
{
byte data[DRBG_SEED_LEN];
int i;
int len = (outSz / OUTPUT_BLOCK_LEN)
+ ((outSz % OUTPUT_BLOCK_LEN) ? 1 : 0);
int len;
word32 checkBlock;
/* Special case: outSz is 0 and out is NULL. Generate a block to save for
* the continuous test. */
if (outSz == 0) outSz = 1;
len = (outSz / OUTPUT_BLOCK_LEN) + ((outSz % OUTPUT_BLOCK_LEN) ? 1 : 0);
XMEMCPY(data, V, sizeof(data));
for (i = 0; i < len; i++) {
@ -219,14 +230,32 @@ static int Hash_gen(DRBG* drbg, byte* out, word32 outSz, const byte* V)
return DRBG_FAILURE;
}
if (outSz > OUTPUT_BLOCK_LEN) {
checkBlock = *(word32*)drbg->digest;
if (drbg->reseedCtr > 1 && checkBlock == drbg->lastBlock) {
if (drbg->matchCount == 1) {
return DRBG_FAILURE;
}
else {
if (i == len) {
len++;
}
drbg->matchCount = 1;
}
}
else {
drbg->matchCount = 0;
drbg->lastBlock = checkBlock;
}
if (outSz >= OUTPUT_BLOCK_LEN) {
XMEMCPY(out, drbg->digest, OUTPUT_BLOCK_LEN);
outSz -= OUTPUT_BLOCK_LEN;
out += OUTPUT_BLOCK_LEN;
array_add_one(data, DRBG_SEED_LEN);
}
else {
else if (out != NULL && outSz != 0) {
XMEMCPY(out, drbg->digest, outSz);
outSz = 0;
}
}
XMEMSET(data, 0, sizeof(data));
@ -263,7 +292,6 @@ static int Hash_DRBG_Generate(DRBG* drbg, byte* out, word32 outSz)
byte type = drbgGenerateH;
word32 reseedCtr = drbg->reseedCtr;
drbg->reseedCtr++;
if (Hash_gen(drbg, out, outSz, drbg->V) != 0 ||
InitSha256(&drbg->sha) != 0 ||
Sha256Update(&drbg->sha, &type, sizeof(type)) != 0 ||
@ -283,6 +311,7 @@ static int Hash_DRBG_Generate(DRBG* drbg, byte* out, word32 outSz)
(byte*)&reseedCtr, sizeof(reseedCtr));
ret = DRBG_SUCCESS;
}
drbg->reseedCtr++;
}
return ret;
@ -303,6 +332,8 @@ static int Hash_DRBG_Instantiate(DRBG* drbg, const byte* seed, word32 seedSz,
sizeof(drbg->V), NULL, 0) == DRBG_SUCCESS) {
drbg->reseedCtr = 1;
drbg->lastBlock = 0;
drbg->matchCount = 0;
ret = DRBG_SUCCESS;
}
@ -339,7 +370,8 @@ int InitRng(RNG* rng)
* size. */
else if (GenerateSeed(&rng->seed, entropy, ENTROPY_NONCE_SZ) == 0 &&
Hash_DRBG_Instantiate(rng->drbg, entropy, ENTROPY_NONCE_SZ,
NULL, 0) == DRBG_SUCCESS) {
NULL, 0) == DRBG_SUCCESS &&
Hash_DRBG_Generate(rng->drbg, NULL, 0) == DRBG_SUCCESS) {
rng->status = DRBG_OK;
ret = 0;
}
@ -376,6 +408,7 @@ int RNG_GenerateBlock(RNG* rng, byte* output, word32 sz)
if (GenerateSeed(&rng->seed, entropy, ENTROPY_SZ) == 0 &&
Hash_DRBG_Reseed(rng->drbg,
entropy, ENTROPY_SZ) == DRBG_SUCCESS &&
Hash_DRBG_Generate(rng->drbg, NULL, 0) == DRBG_SUCCESS &&
Hash_DRBG_Generate(rng->drbg, output, sz) == DRBG_SUCCESS) {
ret = 0;