public class AESCounterRNG extends Random implements RepeatableRNG
Non-linear random number generator based on the AES block cipher in counter mode. Uses the seed as a key to encrypt a 128-bit counter using AES(Rijndael).
By default, we only use a 128-bit key for the cipher because any larger key requires
the inconvenience of installing the unlimited strength cryptography policy
files for the Java platform. Larger keys may be used (192 or 256 bits) but if the
cryptography policy files are not installed, a
GeneralSecurityException
will be thrown.
NOTE: Because instances of this class require 128-bit seeds, it is not
possible to seed this RNG using the Random.setSeed(long)
method inherited
from Random
. Calls to this method will have no effect.
Instead the seed must be set by a constructor.
NOTE: THIS CLASS IS NOT SERIALIZABLE
Constructor and Description |
---|
AESCounterRNG()
Creates a new RNG and seeds it using 128 bits from the default seeding strategy.
|
AESCounterRNG(byte[] seed)
Creates an RNG and seeds it with the specified seed data.
|
AESCounterRNG(int seedSizeBytes)
Seed the RNG using the default seed generation strategy to create a seed of the
specified size.
|
AESCounterRNG(SeedGenerator seedGenerator)
Seed the RNG using the provided seed generation strategy to create a 128-bit
seed.
|
Modifier and Type | Method and Description |
---|---|
byte[] |
getSeed() |
protected int |
next(int bits) |
public AESCounterRNG() throws GeneralSecurityException
GeneralSecurityException
- If there is a problem initialising the AES cipher.public AESCounterRNG(SeedGenerator seedGenerator) throws SeedException, GeneralSecurityException
seedGenerator
- The seed generation strategy that will provide
the seed value for this RNG.SeedException
- If there is a problem generating a seed.GeneralSecurityException
- If there is a problem initialising the AES cipher.public AESCounterRNG(int seedSizeBytes) throws GeneralSecurityException
seedSizeBytes
- The number of bytes to use for seed data. Valid values
are 16 (128 bits), 24 (192 bits) and 32 (256 bits). Any other values will
result in an exception from the AES implementation.GeneralSecurityException
- If there is a problem initialising the AES cipher.public AESCounterRNG(byte[] seed) throws GeneralSecurityException
seed
- The seed data used to initialise the RNG.GeneralSecurityException
- If there is a problem initialising the AES cipher.public byte[] getSeed()
getSeed
in interface RepeatableRNG
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