/*
* This function expands the internal state of the prng to fulfill any number
* of bytes we need for this request. We only use this call if we need more
* than can be supplied by a single call to SHA256_HashBuf.
*
* This function is specified in NIST SP 800-90 section 10.1.1.4, Hashgen
*/
static void
prng_Hashgen(RNGContext *rng, PRUint8 *returned_bytes,
unsigned int no_of_returned_bytes)
{
PRUint8 data[VSize(rng)];
PRUint8 thisHash[SHA256_LENGTH];
PORT_Memcpy(data, V(rng), VSize(rng));
while (no_of_returned_bytes) {
SHA256Context ctx;
unsigned int len;
unsigned int carry;
SHA256_Begin(&ctx);
SHA256_Update(&ctx, data, sizeof data);
SHA256_End(&ctx, thisHash, &len, SHA256_LENGTH);
if (no_of_returned_bytes < SHA256_LENGTH) {
len = no_of_returned_bytes;
}
PORT_Memcpy(returned_bytes, thisHash, len);
returned_bytes += len;
no_of_returned_bytes -= len;
/* The carry parameter is a bool (increment or not).
* This increments data if no_of_returned_bytes is not zero */
carry = no_of_returned_bytes;
PRNG_ADD_CARRY_ONLY(data, (sizeof data) - 1, carry);
}
PORT_Memset(data, 0, sizeof data);
PORT_Memset(thisHash, 0, sizeof thisHash);
}
/*
* Generates new random bytes and advances the internal prng state.
* additional bytes are only used in algorithm testing.
*
* This function is specified in NIST SP 800-90 section 10.1.1.4
*/
static SECStatus
prng_generateNewBytes(RNGContext *rng,
PRUint8 *returned_bytes, unsigned int no_of_returned_bytes,
const PRUint8 *additional_input,
unsigned int additional_input_len)
{
PRUint8 H[SHA256_LENGTH]; /* both H and w since they
* aren't used concurrently */
unsigned int carry;
int k1, k2;
if (!rng->isValid) {
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
return SECFailure;
}
/* This code only triggers during tests, normal
* prng operation does not use additional_input */
if (additional_input){
SHA256Context ctx;
/* NIST SP 800-90 defines two temporaries in their calculations,
* w and H. These temporaries are the same lengths, and used
* at different times, so we use the following macro to collapse
* them to the same variable, but keeping their unique names for
* easy comparison to the spec */
#define w H
rng->V_type = prngAdditionalDataType;
SHA256_Begin(&ctx);
SHA256_Update(&ctx, rng->V_Data, sizeof rng->V_Data);
SHA256_Update(&ctx, additional_input, additional_input_len);
SHA256_End(&ctx, w, NULL, sizeof w);
PRNG_ADD_BITS_AND_CARRY(V(rng), VSize(rng), w, sizeof w)
PORT_Memset(w, 0, sizeof w);
#undef w
}
if (no_of_returned_bytes == SHA256_LENGTH) {
/* short_cut to hashbuf and save a copy and a clear */
SHA256_HashBuf(returned_bytes, V(rng), VSize(rng) );
} else {
prng_Hashgen(rng, returned_bytes, no_of_returned_bytes);
}
/* advance our internal state... */
rng->V_type = prngGenerateByteType;
SHA256_HashBuf(H, rng->V_Data, sizeof rng->V_Data);
PRNG_ADD_BITS_AND_CARRY(V(rng), VSize(rng), H, sizeof H)
PRNG_ADD_BITS(V(rng), VSize(rng), rng->C, sizeof rng->C);
PRNG_ADD_BITS_AND_CARRY(V(rng), VSize(rng), rng->reseed_counter,
sizeof rng->reseed_counter)
PRNG_ADD_CARRY_ONLY(rng->reseed_counter,(sizeof rng->reseed_counter)-1, 1);
/* continuous rng check */
if (memcmp(V(rng), rng->oldV, sizeof rng->oldV) == 0) {
rng->isValid = PR_FALSE;
PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
return SECFailure;
}
PORT_Memcpy(rng->oldV, V(rng), sizeof rng->oldV);
return SECSuccess;
}
/*
* This function expands the internal state of the prng to fulfill any number
* of bytes we need for this request. We only use this call if we need more
* than can be supplied by a single call to SHA256_HashBuf.
*
* This function is specified in NIST SP 800-90 section 10.1.1.4, Hashgen
*/
static void
prng_Hashgen(RNGContext *rng, PRUint8 *returned_bytes,
unsigned int no_of_returned_bytes)
{
PRUint8 data[VSize(rng)];
PORT_Memcpy(data, V(rng), VSize(rng));
while (no_of_returned_bytes) {
SHA256Context ctx;
unsigned int len;
unsigned int carry;
int k1;
SHA256_Begin(&ctx);
SHA256_Update(&ctx, data, sizeof data);
SHA256_End(&ctx, returned_bytes, &len, no_of_returned_bytes);
returned_bytes += len;
no_of_returned_bytes -= len;
/* The carry parameter is a bool (increment or not).
* This increments data if no_of_returned_bytes is not zero */
PRNG_ADD_CARRY_ONLY(data, (sizeof data)- 1, no_of_returned_bytes);
}
PORT_Memset(data, 0, sizeof data);
}
