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**All Superinterfaces:**- Cloneable

**Known Implementing Classes:**- ARCFour, BasePRNG, CSPRNG, Fortuna, Fortuna.Generator, ICMGenerator, MDGenerator, PBKDF2, UMacGenerator

The basic visible methods of any pseudo-random number generator.

The [HAC] defines a PRNG (as implemented in this library) as follows:

- "5.6 Definition: A pseudorandom bit generator (PRBG) is said to pass the
*next-bit test*if there is no polynomial-time algorithm which, on input of the first`L`

bits of an output sequence`S`

, can predict the`(L+1)`

^{st}bit of`S`

with a probability significantly greater than`1/2`

." - "5.8 Definition: A PRBG that passes the
*next-bit test*(possibly under some plausible but unproved mathematical assumption such as the intractability of factoring integers) is called a*cryptographically secure pseudorandom bit generator*(CSPRBG)."

**IMPLEMENTATION NOTE**: Although all the concrete classes in this
package implement the `Cloneable`

interface, it is important to note
here that such an operation, for those algorithms that use an underlying
symmetric key block cipher, **DOES NOT** clone any session key material
that may have been used in initialising the source PRNG (the instance to be
cloned). Instead a clone of an already initialised PRNG, that uses an
underlying symmetric key block cipher, is another instance with a clone of
the same cipher that operates with the **same block size** but without
any knowledge of neither key material nor key size.

References:

- [HAC]: Handbook of
Applied Cryptography.

CRC Press, Inc. ISBN 0-8493-8523-7, 1997

Menezes, A., van Oorschot, P. and S. Vanstone.

## Method Summary

`void`

`addRandomByte(byte b)`

- Supplement, or possibly replace, the random state of this PRNG with a random byte.

`void`

`addRandomBytes(byte[] in)`

- Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.

`void`

`addRandomBytes(byte[] in, int offset, int length)`

- Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.

`Object`

`clone()`

- Returns a clone copy of this instance.

`void`

`String`

`name()`

- Returns the canonical name of this instance.

`byte`

`nextByte()`

- Returns the next 8 bits of random data generated from this instance.

`void`

`nextBytes(byte[] out, int offset, int length)`

- Fills the designated byte array, starting from byte at index
`offset`

, for a maximum of`length`

bytes with the output of this generator instance.

public void addRandomByte(byte b)

Supplement, or possibly replace, the random state of this PRNG with a random byte.Implementations are not required to implement this method in any meaningful way; this may be a no-operation, and implementations may throw an

`UnsupportedOperationException`

.

Parameters:`b`

- The byte to add.

public void addRandomBytes(byte[] in)

Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.Implementations are not required to implement this method in any meaningful way; this may be a no-operation, and implementations may throw an

`UnsupportedOperationException`

.

Parameters:`in`

- The buffer of new random bytes to add.

public void addRandomBytes(byte[] in, int offset, int length)

Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.Implementations are not required to implement this method in any meaningful way; this may be a no-operation, and implementations may throw an

`UnsupportedOperationException`

.

Parameters:`in`

- The buffer of new random bytes to add.`offset`

- The offset from whence to begin reading random bytes.`length`

- The number of random bytes to add.

Throws:`IndexOutOfBoundsException`

- Ifoffset,length, oroffset+lengthis out of bounds.

public Object clone() throws CloneNotSupportedException

Returns a clone copy of this instance.

Returns:- a clone copy of this instance.

public void init(Map<K,V> attributes)

Initialises the pseudo-random number generator scheme with the appropriate attributes.

Parameters:`attributes`

- a set of name-value pairs that describe the desired future instance behaviour.

Throws:`IllegalArgumentException`

- if at least one of the defined name/ value pairs contains invalid data.

public String name()

Returns the canonical name of this instance.

Returns:- the canonical name of this instance.

public byte nextByte() throws IllegalStateException, LimitReachedException

Returns the next 8 bits of random data generated from this instance.

Returns:- the next 8 bits of random data generated from this instance.

Throws:`IllegalStateException`

- if the instance is not yet initialised.`LimitReachedException`

- if this instance has reached its theoretical limit for generating non-repetitive pseudo-random data.

public void nextBytes(byte[] out, int offset, int length) throws IllegalStateException, LimitReachedException

Fills the designated byte array, starting from byte at index`offset`

, for a maximum of`length`

bytes with the output of this generator instance.

Parameters:`out`

- the placeholder to contain the generated random bytes.`offset`

- the starting index inoutto consider. This method does nothing if this parameter is not within`0`

and`out.length`

.`length`

- the maximum number of required random bytes. This method does nothing if this parameter is less than`1`

.

Throws:`IllegalStateException`

- if the instance is not yet initialised.`LimitReachedException`

- if this instance has reached its theoretical limit for generating non-repetitive pseudo-random data.

IRandom.java --
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