**javacard.security** 
 ====Class RandomData  ====
  *[[javacard:java-card-api:object|java.lang.Object]] \\ 


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public abstract class **RandomData**extends [[javacard:java-card-api:Object|Object]] 



The RandomData abstract class is the base class for random number generation.
 Implementations of RandomData
 algorithms must extend this class and implement all the abstract methods.




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^ Field Summary ^^ 
| **static byte** | **[[javacard:java-card-api:RandomData#ALG_PSEUDO_RANDOM|ALG_PSEUDO_RANDOM]] **          Utility pseudo-random number generation algorithms. |
| **static byte** | **[[javacard:java-card-api:RandomData#ALG_SECURE_RANDOM|ALG_SECURE_RANDOM]] **          Cryptographically secure random number generation algorithms. |

 




^ Constructor Summary ^^ 
| **protected ** | **[[javacard:java-card-api:RandomData#RandomData()|RandomData]] **()          Protected constructor for subclassing. |

 




^ Method Summary ^^ 
| **abstract  void** | **[[javacard:java-card-api:RandomData#generateData(byte[], short, short)|generateData]] **(byte[] buffer,short offset,short length)          Generates random data. |
| **static [[javacard:java-card-api:RandomData|RandomData]] ** | **[[javacard:java-card-api:RandomData#getInstance(byte)|getInstance]] **(byte algorithm)          Creates a RandomData instance of the selected algorithm. |
| **abstract  void** | **[[javacard:java-card-api:RandomData#setSeed(byte[], short, short)|setSeed]] **(byte[] buffer,short offset,short length)          Seeds the random data generator. |

 

^ Methods inherited from class java.lang.Object ^ 
| [[javacard:java-card-api:Object#equals(java.lang.Object)|equals]]  |

 






^ Field Detail ^ 



 === ALG_PSEUDO_RANDOM === 
public static final byte **ALG_PSEUDO_RANDOM**

Utility pseudo-random number generation algorithms. The random number sequence
 generated by this algorithm need not be the same even if seeded with the same
 seed data.
  Even if a transaction is in progress, the update of the internal state
 shall not participate in the transaction.


**See Also:**[[javacard:java-card-api:constant-values#javacard.security.RandomData.ALG_PSEUDO_RANDOM|Constant Field Values]]  
 

 
 


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 === ALG_SECURE_RANDOM === 
public static final byte **ALG_SECURE_RANDOM**

Cryptographically secure random number generation algorithms.


**See Also:**[[javacard:java-card-api:constant-values#javacard.security.RandomData.ALG_SECURE_RANDOM|Constant Field Values]]  
 

 
 






^ Constructor Detail ^ 



 === RandomData === 
protected **RandomData**()

Protected constructor for subclassing.

 
 






^ Method Detail ^ 



 === getInstance === 
public static final [[javacard:java-card-api:RandomData|RandomData]]  **getInstance**(byte algorithm)
throws [[javacard:java-card-api:CryptoException|CryptoException]] 

Creates a RandomData instance of the selected algorithm.
 The pseudo random RandomData instance's seed is initialized to a internal default value.

 
 

**Parameters:**algorithm - the desired random number algorithm. Valid codes listed in ALG_* constants above. See [[javacard:java-card-api:RandomData#ALG_PSEUDO_RANDOM|ALG_PSEUDO_RANDOM]] .
 
 
**Returns:**the RandomData object instance of the requested algorithm
 
 
**Throws:**
[[javacard:java-card-api:CryptoException|CryptoException]]  - with the following reason codes:
 \\ 
 
  *CryptoException.NO_SUCH_ALGORITHM if the requested algorithm is not supported.
 \\   
 

 
 



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 === generateData === 
public abstract void **generateData**(byte[] buffer,
short offset,
short length)
throws [[javacard:java-card-api:CryptoException|CryptoException]] 

Generates random data.

 
 

**Parameters:**buffer - the output buffer 
 
offset - the offset into the output buffer 
 
length - the length of random data to generate
 
 
**Throws:**
[[javacard:java-card-api:CryptoException|CryptoException]]  - with the following reason codes:
 \\ 
 
  *CryptoException.ILLEGAL_VALUE if the length parameter is zero.
 \\   
 

 
 



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 === setSeed === 
public abstract void **setSeed**(byte[] buffer,
short offset,
short length)

Seeds the random data generator.

 
 

**Parameters:**buffer - the input buffer 
 
offset - the offset into the input buffer 
 
length - the length of the seed data