/**
* Populate a passed in array with random data.
*
* @param output output array for generated bits.
* @param additionalInput additional input to be added to the DRBG in this step.
* @param predictionResistant true if a reseed should be forced, false otherwise.
*
* @return number of bits generated, -1 if a reseed required.
*/
public int Generate(byte[] output, byte[] additionalInput, bool predictionResistant)
{
if (mIsTdea)
{
if (mReseedCounter > TDEA_RESEED_MAX)
{
return(-1);
}
if (DrbgUtilities.IsTooLarge(output, TDEA_MAX_BITS_REQUEST / 8))
{
throw new ArgumentException("Number of bits per request limited to " + TDEA_MAX_BITS_REQUEST, "output");
}
}
else
{
if (mReseedCounter > AES_RESEED_MAX)
{
return(-1);
}
if (DrbgUtilities.IsTooLarge(output, AES_MAX_BITS_REQUEST / 8))
{
throw new ArgumentException("Number of bits per request limited to " + AES_MAX_BITS_REQUEST, "output");
}
}
if (predictionResistant)
{
CTR_DRBG_Reseed_algorithm(additionalInput);
additionalInput = null;
}
if (additionalInput != null)
{
additionalInput = Block_Cipher_df(additionalInput, mSeedLength);
CTR_DRBG_Update(additionalInput, mKey, mV);
}
else
{
additionalInput = new byte[mSeedLength];
}
byte[] tmp = new byte[mV.Length];
mEngine.Init(true, new KeyParameter(ExpandKey(mKey)));
for (int i = 0; i <= output.Length / tmp.Length; i++)
{
int bytesToCopy = ((output.Length - i * tmp.Length) > tmp.Length)
? tmp.Length
: (output.Length - i * mV.Length);
if (bytesToCopy != 0)
{
AddOneTo(mV);
mEngine.ProcessBlock(mV, 0, tmp, 0);
Array.Copy(tmp, 0, output, i * tmp.Length, bytesToCopy);
}
}
CTR_DRBG_Update(additionalInput, mKey, mV);
mReseedCounter++;
return(output.Length * 8);
}
