/**
* Generates a user-specified number of random bytes.
*
* @param bytes the array to be filled in with random bytes.
*/
public synchronized void engineNextBytes(byte[] result) {
int index = 0;
int todo;
byte[] output = remainder;
if (state == null) {
if (seeder == null) {
seeder = new SecureRandom(SeedGenerator.getSystemEntropy());
seeder.engineSetSeed(engineGenerateSeed(DIGEST_SIZE));
}
byte[] seed = new byte[DIGEST_SIZE];
seeder.engineNextBytes(seed);
state = digest.digest(seed);
}
// Use remainder from last time
int r = remCount;
if (r > 0) {
// How many bytes?
todo =
(result.length - index) < (DIGEST_SIZE - r) ? (result.length - index) : (DIGEST_SIZE - r);
// Copy the bytes, zero the buffer
for (int i = 0; i < todo; i++) {
result[i] = output[r];
output[r++] = 0;
}
remCount += todo;
index += todo;
}
// If we need more bytes, make them.
while (index < result.length) {
// Step the state
digest.update(state);
output = digest.digest();
updateState(state, output);
// How many bytes?
todo = (result.length - index) > DIGEST_SIZE ? DIGEST_SIZE : result.length - index;
// Copy the bytes, zero the buffer
for (int i = 0; i < todo; i++) {
result[index++] = output[i];
output[i] = 0;
}
remCount += todo;
}
// Store remainder for next time
remainder = output;
remCount %= DIGEST_SIZE;
}
static {
/*
* Call to SeedGenerator.generateSeed() to add additional
* seed material (likely from the Native implementation).
*/
seeder = new SecureRandom(SeedGenerator.getSystemEntropy());
byte[] b = new byte[DIGEST_SIZE];
SeedGenerator.generateSeed(b);
seeder.engineSetSeed(b);
}