java.lang.Object
- java.util.Random
- - io.github.pr0methean.betterrandom.prng.BaseRandom
  - - io.github.pr0methean.betterrandom.prng.CipherCounterRandom
    - - io.github.pr0methean.betterrandom.prng.AesCounterRandom

All Implemented Interfaces:

ByteArrayReseedableRandom, EntropyCountingRandom, Java8CompatRandom, RepeatableRandom, SeekableRandom, Dumpable, Serializable
```
public class AesCounterRandom
extends CipherCounterRandom
```
CipherCounterRandom using AES (Rijndael).

Keys larger than 128 bits, and thus seeds larger than 256 bits, require unlimited strength cryptography policy files on closed-source JDKs.

NOTE: Because instances of this class require 128-bit seeds, it is not possible to seed this RNG using the CipherCounterRandom.setSeed(long) method inherited from Random until the seed array has been set.

Author:

Daniel Dyer, Chris Hennick

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field	Description
`protected Cipher`	`cipher`	The AES cipher that will generate the pseudorandom numbers.
`static int`	`MAX_SEED_LENGTH_BYTES`	Maximum total length of the seed, including both key and initial counter value.

Fields inherited from class io.github.pr0methean.betterrandom.prng.CipherCounterRandom
counter, currentBlock, index

Fields inherited from class io.github.pr0methean.betterrandom.prng.BaseRandom
ENTROPY_OF_DOUBLE, ENTROPY_OF_FLOAT, entropyBits, lock, randomSeeder, seed, superConstructorFinished

Constructor Summary

Constructors
Constructor	Description
`AesCounterRandom()`	Creates a new RNG and seeds it using 256 bits from the `DefaultSeedGenerator`.
`AesCounterRandom(byte[] seed)`	Creates an RNG and seeds it with the specified seed data.
`AesCounterRandom(int seedSizeBytes)`	Seed the RNG using the `DefaultSeedGenerator` to create a seed of the specified size.
`AesCounterRandom(SeedGenerator seedGenerator)`	Seed the RNG using the provided seed generation strategy to create a 256-bit seed.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`MoreObjects.ToStringHelper`	`addSubclassFields(MoreObjects.ToStringHelper original)`	Adds the fields that were not inherited from BaseRandom to the given `MoreObjects.ToStringHelper` for dumping.
`protected void`	`createCipher()`	Creates the cipher that `CipherCounterRandom.doCipher(byte[], byte[])` will invoke.
`protected MessageDigest`	`createHash()`	Returns the hash that will be used to combine seeds.
`protected void`	`doCipher(byte[] input, byte[] output)`	Executes the cipher.
`int`	`getBlocksAtOnce()`	Returns how many consecutive values of the counter are encrypted at once, in order to reduce the number of calls to Cipher methods.
`int`	`getBytesAtOnce()`	Returns the number of random bytes that can be precalculated at once, which is normally `getCounterSizeBytes() * getBlocksAtOnce()`.
`int`	`getCounterSizeBytes()`	Returns the length of the counter, which should equal the cipher's block size.
`protected int`	`getKeyLength(int inputLength)`	Returns the length of the key that should be extracted from a seed of a given length.
`int`	`getMaxKeyLengthBytes()`	Returns the maximum length in bytes of an AES key, which is `Math.min(Cipher.getMaxAllowedKeyLength("AES/ECB/NoPadding") / 8, 32)`.
`int`	`getMaxTotalSeedLengthBytes()`	Returns the maximum seed length, including both the cipher key and a new counter value.
`protected int`	`getMinSeedLength()`	Returns the minimum seed length.
`int`	`getNewSeedLength()`	Returns the longest supported seed length.
`protected void`	`setKey(byte[] key)`	Sets the key on the cipher.
`protected void`	`setSeedInternal(byte[] seed)`	Sets the seed, and should be overridden to set other state that derives from the seed.

Methods inherited from class io.github.pr0methean.betterrandom.prng.CipherCounterRandom
advance, initTransientFields, next, nextBlock, setSeed, setSeed, supportsMultipleSeedLengths

Methods inherited from class io.github.pr0methean.betterrandom.prng.BaseRandom
checkLength, creditEntropyForNewSeed, debitEntropy, doubles, doubles, doubles, doubles, dump, entropyOfInt, entropyOfLong, fallbackSetSeedIfInitialized, gaussians, gaussians, getEntropyBits, getRandomSeeder, getSeed, internalNextGaussian, ints, ints, ints, ints, lockForNextGaussian, longs, longs, longs, longs, needsReseedingEarly, nextBoolean, nextBytes, nextDouble, nextDouble, nextDouble, nextDoubleNoEntropyDebit, nextElement, nextElement, nextEnum, nextFloat, nextGaussian, nextInt, nextInt, nextInt, nextLong, nextLong, nextLong, nextLongNoEntropyDebit, preferSeedWithLong, setRandomSeeder, unlockForNextGaussian, usesParallelStreams, withProbability, withProbabilityInternal

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.github.pr0methean.betterrandom.RepeatableRandom
getSeed

- Field Detail
  - cipher
```
protected transient Cipher cipher
```
    The AES cipher that will generate the pseudorandom numbers.
  - MAX_SEED_LENGTH_BYTES
```
public static final int MAX_SEED_LENGTH_BYTES
```
    Maximum total length of the seed, including both key and initial counter value.
- Constructor Detail
  - AesCounterRandom
```
public AesCounterRandom()
                 throws SeedException
```
    Creates a new RNG and seeds it using 256 bits from the DefaultSeedGenerator.
    
    Throws:
    
    SeedException - if the DefaultSeedGenerator fails to generate a seed.
  - AesCounterRandom
```
public AesCounterRandom(SeedGenerator seedGenerator)
                 throws SeedException
```
    Seed the RNG using the provided seed generation strategy to create a 256-bit seed.
    
    Parameters:
    
    seedGenerator - The seed generation strategy that will provide the seed value for this RNG.
    
    Throws:
    
    SeedException - if there is a problem generating a seed.
  - AesCounterRandom
```
public AesCounterRandom(int seedSizeBytes)
                 throws SeedException
```
    Seed the RNG using the DefaultSeedGenerator to create a seed of the specified size.
    
    Parameters:
    
    seedSizeBytes - The number of bytes to use for seed data. Valid values range from 16 to MAX_SEED_LENGTH_BYTES.
    
    Throws:
    
    SeedException - if the DefaultSeedGenerator fails to generate a seed.
  - AesCounterRandom
```
public AesCounterRandom(byte[] seed)
```
    Creates an RNG and seeds it with the specified seed data.
    
    Parameters:
    
    seed - The seed data used to initialize the RNG. Length must be at least 16 and no more than MAX_SEED_LENGTH_BYTES.
- Method Detail
  - getBlocksAtOnce
```
public int getBlocksAtOnce()
```
    Description copied from class: CipherCounterRandom
    
    Returns how many consecutive values of the counter are encrypted at once, in order to reduce the number of calls to Cipher methods. Each counter value encrypts to yield a "block" of pseudorandom data. Changing this value won't change the output if the cipher is running in block mode, but it may impact performance.
    
    Specified by:
    
    getBlocksAtOnce in class CipherCounterRandom
    
    Returns:
    
    the number of blocks (counter values) to encrypt at once
  - getBytesAtOnce
```
public int getBytesAtOnce()
```
    Description copied from class: CipherCounterRandom
    
    Returns the number of random bytes that can be precalculated at once, which is normally getCounterSizeBytes() * getBlocksAtOnce().
    
    Overrides:
    
    getBytesAtOnce in class CipherCounterRandom
    
    Returns:
    
    the number of random bytes that can be precalculated at once
  - getMaxTotalSeedLengthBytes
```
public int getMaxTotalSeedLengthBytes()
```
    Description copied from class: CipherCounterRandom
    
    Returns the maximum seed length, including both the cipher key and a new counter value.
    
    Overrides:
    
    getMaxTotalSeedLengthBytes in class CipherCounterRandom
    
    Returns:
    
    the maximum seed length
  - getMinSeedLength
```
protected int getMinSeedLength()
```
    Description copied from class: CipherCounterRandom
    
    Returns the minimum seed length.
    
    Specified by:
    
    getMinSeedLength in class CipherCounterRandom
    
    Returns:
    
    the minimum seed length
  - getCounterSizeBytes
```
public int getCounterSizeBytes()
```
    Description copied from class: CipherCounterRandom
    
    Returns the length of the counter, which should equal the cipher's block size.
    
    Overrides:
    
    getCounterSizeBytes in class CipherCounterRandom
    
    Returns:
    
    the length of the counter
  - getMaxKeyLengthBytes
```
public int getMaxKeyLengthBytes()
```
    Returns the maximum length in bytes of an AES key, which is Math.min(Cipher.getMaxAllowedKeyLength("AES/ECB/NoPadding") / 8, 32). If the seed is longer than this, part of it becomes the counter's initial value. Otherwise, the full seed becomes the AES key and the counter is initially zero.
    
    Specified by:
    
    getMaxKeyLengthBytes in class CipherCounterRandom
    
    Returns:
    
    the maximum length in bytes of an AES key.
  - getKeyLength
```
protected int getKeyLength(int inputLength)
```
    Description copied from class: CipherCounterRandom
    
    Returns the length of the key that should be extracted from a seed of a given length. During the initial seeding, whatever part of the seed does not become the key, becomes the counter's initial value.
    
    Specified by:
    
    getKeyLength in class CipherCounterRandom
    
    Parameters:
    
    inputLength - the length of the whole seed
    
    Returns:
    
    the length of the key
  - createHash
```
protected MessageDigest createHash()
```
    Description copied from class: CipherCounterRandom
    
    Returns the hash that will be used to combine seeds. Only called on construction and deserialization.
    
    Specified by:
    
    createHash in class CipherCounterRandom
    
    Returns:
    
    a resettable MessageDigest
  - createCipher
```
protected void createCipher()
```
    Description copied from class: CipherCounterRandom
    
    Creates the cipher that CipherCounterRandom.doCipher(byte[], byte[]) will invoke. CipherCounterRandom.setKey(byte[]) will be called before the cipher is used.
    
    Specified by:
    
    createCipher in class CipherCounterRandom
  - setSeedInternal
```
protected void setSeedInternal(byte[] seed)
```
    Description copied from class: BaseRandom
    
    Sets the seed, and should be overridden to set other state that derives from the seed. Called by BaseRandom.setSeed(byte[]), constructors, and readObject(ObjectInputStream). When called after initialization, the BaseRandom.lock is always held.
    
    Overrides:
    
    setSeedInternal in class CipherCounterRandom
    
    Parameters:
    
    seed - The new seed.
  - setKey
```
protected void setKey(byte[] key)
               throws InvalidKeyException
```
    Description copied from class: CipherCounterRandom
    
    Sets the key on the cipher. Always called with lock held.
    
    Specified by:
    
    setKey in class CipherCounterRandom
    
    Parameters:
    
    key - the new key
    
    Throws:
    
    InvalidKeyException - if the cipher rejects the key
  - getNewSeedLength
```
public int getNewSeedLength()
```
    Returns the longest supported seed length.
    
    Specified by:
    
    getNewSeedLength in interface ByteArrayReseedableRandom
    
    Overrides:
    
    getNewSeedLength in class CipherCounterRandom
    
    Returns:
    
    The desired length of a new byte-array seed.
  - addSubclassFields
```
public MoreObjects.ToStringHelper addSubclassFields(MoreObjects.ToStringHelper original)
```
    Description copied from class: BaseRandom
    
    Adds the fields that were not inherited from BaseRandom to the given MoreObjects.ToStringHelper for dumping.
    
    Specified by:
    
    addSubclassFields in class BaseRandom
    
    Parameters:
    
    original - a MoreObjects.ToStringHelper object.
    
    Returns:
    
    original with the fields not inherited from BaseRandom written to it.
  - doCipher
```
protected void doCipher(byte[] input,
                        byte[] output)
                 throws GeneralSecurityException
```
    Description copied from class: CipherCounterRandom
    
    Executes the cipher.
    
    Specified by:
    
    doCipher in class CipherCounterRandom
    
    Parameters:
    
    input - an array of input whose length is equal to CipherCounterRandom.getBytesAtOnce()
    
    output - an array of output whose length is equal to CipherCounterRandom.getBytesAtOnce()
    
    Throws:
    
    GeneralSecurityException - if an internal error occurs in the cipher

Class AesCounterRandom

Field Summary

Fields inherited from class io.github.pr0methean.betterrandom.prng.CipherCounterRandom

Fields inherited from class io.github.pr0methean.betterrandom.prng.BaseRandom

Constructor Summary

Method Summary

Methods inherited from class io.github.pr0methean.betterrandom.prng.CipherCounterRandom

Methods inherited from class io.github.pr0methean.betterrandom.prng.BaseRandom

Methods inherited from class java.lang.Object

Methods inherited from interface io.github.pr0methean.betterrandom.RepeatableRandom

Field Detail

cipher

MAX_SEED_LENGTH_BYTES

Constructor Detail

AesCounterRandom

AesCounterRandom

AesCounterRandom

AesCounterRandom

Method Detail

getBlocksAtOnce

getBytesAtOnce

getMaxTotalSeedLengthBytes

getMinSeedLength

getCounterSizeBytes

getMaxKeyLengthBytes

getKeyLength

createHash

createCipher

setSeedInternal

setKey

getNewSeedLength

addSubclassFields

doCipher