java.security.SecureRandom

All Implemented Interfaces:: Serializable, RandomGenerator

public class SecureRandom extends Random

This class provides a cryptographically strong random number generator (RNG).

A cryptographically strong random number minimally complies with the statistical random number generator tests specified in FIPS 140-2, Security Requirements for Cryptographic Modules, section 4.9.1. Additionally, SecureRandom must produce non-deterministic output. Therefore, any seed material passed to a SecureRandom object must be unpredictable, and all SecureRandom output sequences must be cryptographically strong, as described in RFC 4086: Randomness Requirements for Security.

Many SecureRandom implementations are in the form of a pseudo-random number generator (PRNG, also known as deterministic random bits generator or DRBG), which means they use a deterministic algorithm to produce a pseudo-random sequence from a random seed. Other implementations may produce true random numbers, and yet others may use a combination of both techniques.

A caller obtains a SecureRandom instance via the no-argument constructor or one of the getInstance methods. For example:

SecureRandom r1 = new SecureRandom();
SecureRandom r2 = SecureRandom.getInstance("NativePRNG");
SecureRandom r3 = SecureRandom.getInstance("DRBG",
        DrbgParameters.instantiation(128, RESEED_ONLY, null));

The third statement above returns a SecureRandom object of the specific algorithm supporting the specific instantiate parameters. The implementation's effective instantiated parameters must match this minimum request but is not necessarily the same. For example, even if the request does not require a certain feature, the actual instantiation can provide the feature. An implementation may lazily instantiate a SecureRandom until it's actually used, but the effective instantiate parameters must be determined right after it's created and getParameters() should always return the same result unchanged.

Typical callers of SecureRandom invoke the following methods to retrieve random bytes:

SecureRandom random = new SecureRandom();
byte[] bytes = new byte[20];
random.nextBytes(bytes);

Callers may also invoke the generateSeed(int) method to generate a given number of seed bytes (to seed other random number generators, for example):

byte[] seed = random.generateSeed(20);

A newly created PRNG SecureRandom object is not seeded (except if it is created by SecureRandom(byte[])). The first call to nextBytes will force it to seed itself from an implementation- specific entropy source. This self-seeding will not occur if setSeed was previously called.

A SecureRandom can be reseeded at any time by calling the reseed or setSeed method. The reseed method reads entropy input from its entropy source to reseed itself. The setSeed method requires the caller to provide the seed.

Please note that reseed may not be supported by all SecureRandom implementations.

Some SecureRandom implementations may accept a SecureRandomParameters parameter in its nextBytes(byte[], SecureRandomParameters) and reseed(SecureRandomParameters) methods to further control the behavior of the methods.

Note: Depending on the implementation, the generateSeed, reseed and nextBytes methods may block as entropy is being gathered, for example, if the entropy source is /dev/random on various Unix-like operating systems.

Thread safety

SecureRandom objects are safe for use by multiple concurrent threads.

Implementation Requirements:

A SecureRandom service provider can advertise that it is thread-safe by setting the service provider attribute "ThreadSafe" to "true" when registering the provider. Otherwise, this class will instead synchronize access to the following methods of the SecureRandomSpi implementation:

Since:

1.1

External Specifications

See Also:

Nested Class Summary

Nested classes/interfaces inherited from interface RandomGenerator
RandomGenerator.ArbitrarilyJumpableGenerator, RandomGenerator.JumpableGenerator, RandomGenerator.LeapableGenerator, RandomGenerator.SplittableGenerator, RandomGenerator.StreamableGenerator

Modifier and Type

Interface

Description

static interface

RandomGenerator.ArbitrarilyJumpableGenerator

This interface is designed to provide a common protocol for objects that generate sequences of pseudorandom values and can easily jump forward, by an arbitrary amount, to a distant point in the state cycle.

static interface

RandomGenerator.JumpableGenerator

This interface is designed to provide a common protocol for objects that generate pseudorandom values and can easily jump forward, by a moderate amount (ex. 2⁶⁴) to a distant point in the state cycle.

static interface

RandomGenerator.LeapableGenerator

This interface is designed to provide a common protocol for objects that generate sequences of pseudorandom values and can easily not only jump but also leap forward, by a large amount (ex. 2¹²⁸), to a very distant point in the state cycle.

static interface

RandomGenerator.SplittableGenerator

This interface is designed to provide a common protocol for objects that generate sequences of pseudorandom values and can be split into two objects (the original one and a new one) each of which obey that same protocol (and therefore can be recursively split indefinitely).

static interface

RandomGenerator.StreamableGenerator

The RandomGenerator.StreamableGenerator interface augments the RandomGenerator interface to provide methods that return streams of RandomGenerator objects.
Constructor Summary

Constructors

Modifier

Constructor

Description

SecureRandom()

Constructs a secure random number generator (RNG) implementing the default random number algorithm.

SecureRandom(byte[] seed)

Constructs a secure random number generator (RNG) implementing the default random number algorithm.

protected

SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider)

Creates a SecureRandom object.
Method Summary

Modifier and Type

Method

Description

byte[]

generateSeed(int numBytes)

Returns the given number of seed bytes, computed using the seed generation algorithm that this class uses to seed itself.

String

getAlgorithm()

Returns the name of the algorithm implemented by this SecureRandom object.

static SecureRandom

getInstance(String algorithm)

Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm.

static SecureRandom

getInstance(String algorithm, String provider)

Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm.

static SecureRandom

getInstance(String algorithm, Provider provider)

Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm.

static SecureRandom

getInstance(String algorithm, SecureRandomParameters params)

Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm and supports the specified SecureRandomParameters request.

static SecureRandom

getInstance(String algorithm, SecureRandomParameters params, String provider)

Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm and supports the specified SecureRandomParameters request.

static SecureRandom

getInstance(String algorithm, SecureRandomParameters params, Provider provider)

Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm and supports the specified SecureRandomParameters request.

static SecureRandom

getInstanceStrong()

Returns a SecureRandom object that was selected by using the algorithms/providers specified in the securerandom.strongAlgorithms Security property.

SecureRandomParameters

getParameters()

Returns the effective SecureRandomParameters for this SecureRandom instance.

final Provider

getProvider()

Returns the provider of this SecureRandom object.

static byte[]

getSeed(int numBytes)

Returns the given number of seed bytes, computed using the seed generation algorithm that this class uses to seed itself.

protected final int

next(int numBits)

Generates an integer containing the user-specified number of pseudo-random bits (right justified, with leading zeros).

void

nextBytes(byte[] bytes)

Generates a user-specified number of random bytes.

void

nextBytes(byte[] bytes, SecureRandomParameters params)

Generates a user-specified number of random bytes with additional parameters.

long

nextLong()

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.

void

reseed()

Reseeds this SecureRandom with entropy input read from its entropy source.

void

reseed(SecureRandomParameters params)

Reseeds this SecureRandom with entropy input read from its entropy source with additional parameters.

void

setSeed(byte[] seed)

Reseeds this random object with the given seed.

void

setSeed(long seed)

Reseeds this random object, using the eight bytes contained in the given long seed.

String

toString()

Returns a Human-readable string representation of this SecureRandom.

Methods inherited from class Random
doubles, doubles, doubles, doubles, from, ints, ints, ints, ints, longs, longs, longs, longs, nextBoolean, nextDouble, nextFloat, nextGaussian, nextInt, nextInt

Modifier and Type

Method

Description

DoubleStream

doubles()

Returns an effectively unlimited stream of pseudorandom double values, each between zero (inclusive) and one (exclusive).

DoubleStream

doubles(double randomNumberOrigin, double randomNumberBound)

Returns an effectively unlimited stream of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

DoubleStream

doubles(long streamSize)

Returns a stream producing the given streamSize number of pseudorandom double values, each between zero (inclusive) and one (exclusive).

DoubleStream

doubles(long streamSize, double randomNumberOrigin, double randomNumberBound)

Returns a stream producing the given streamSize number of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

static Random

from(RandomGenerator generator)

Returns an instance of Random that delegates method calls to the RandomGenerator argument.

IntStream

ints()

Returns an effectively unlimited stream of pseudorandom int values.

IntStream

ints(int randomNumberOrigin, int randomNumberBound)

Returns an effectively unlimited stream of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

IntStream

ints(long streamSize)

Returns a stream producing the given streamSize number of pseudorandom int values.

IntStream

ints(long streamSize, int randomNumberOrigin, int randomNumberBound)

Returns a stream producing the given streamSize number of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

LongStream

longs()

Returns an effectively unlimited stream of pseudorandom long values.

LongStream

longs(long streamSize)

Returns a stream producing the given streamSize number of pseudorandom long values.

LongStream

longs(long randomNumberOrigin, long randomNumberBound)

Returns an effectively unlimited stream of pseudorandom long values, each conforming to the given origin (inclusive) and bound (exclusive).

LongStream

longs(long streamSize, long randomNumberOrigin, long randomNumberBound)

Returns a stream producing the given streamSize number of pseudorandom long, each conforming to the given origin (inclusive) and bound (exclusive).

boolean

nextBoolean()

Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.

double

nextDouble()

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

float

nextFloat()

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

double

nextGaussian()

Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.

int

nextInt()

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

int

nextInt(int bound)

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

Methods inherited from class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Modifier and Type

Method

Description

protected Object

clone()

Creates and returns a copy of this object.

boolean

equals(Object obj)

Indicates whether some other object is "equal to" this one.

protected void

finalize()

Deprecated, for removal: This API element is subject to removal in a future version.
Finalization is deprecated and subject to removal in a future release.

final Class<?>

getClass()

Returns the runtime class of this Object.

int

hashCode()

Returns a hash code value for this object.

final void

notify()

Wakes up a single thread that is waiting on this object's monitor.

final void

notifyAll()

Wakes up all threads that are waiting on this object's monitor.

final void

wait()

Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

final void

wait(long timeoutMillis)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void

wait(long timeoutMillis, int nanos)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Methods inherited from interface RandomGenerator
equiDoubles, isDeprecated, nextDouble, nextDouble, nextExponential, nextFloat, nextFloat, nextGaussian, nextInt, nextLong, nextLong

Modifier and Type

Method

Description

default DoubleStream

equiDoubles(double left, double right, boolean isLeftIncluded, boolean isRightIncluded)

Returns an effectively unlimited stream of pseudorandomly chosen double values, where each value is between the specified left boundary and the specified right boundary.

default boolean

isDeprecated()

Return true if the implementation of RandomGenerator (algorithm) has been marked for deprecation.

default double

nextDouble(double bound)

Returns a pseudorandomly chosen double value between zero (inclusive) and the specified bound (exclusive).

default double

nextDouble(double origin, double bound)

Returns a pseudorandomly chosen double value between the specified origin (inclusive) and the specified bound (exclusive).

default double

nextExponential()

Returns a nonnegative double value pseudorandomly chosen from an exponential distribution whose mean is 1.

default float

nextFloat(float bound)

Returns a pseudorandomly chosen float value between zero (inclusive) and the specified bound (exclusive).

default float

nextFloat(float origin, float bound)

Returns a pseudorandomly chosen float value between the specified origin (inclusive) and the specified bound (exclusive).

default double

nextGaussian(double mean, double stddev)

Returns a double value pseudorandomly chosen from a Gaussian (normal) distribution with a mean and standard deviation specified by the arguments.

default int

nextInt(int origin, int bound)

Returns a pseudorandomly chosen int value between the specified origin (inclusive) and the specified bound (exclusive).

default long

nextLong(long bound)

Returns a pseudorandomly chosen long value between zero (inclusive) and the specified bound (exclusive).

default long

nextLong(long origin, long bound)

Returns a pseudorandomly chosen long value between the specified origin (inclusive) and the specified bound (exclusive).

Constructor Details
- SecureRandom
  public SecureRandom()
  
  Constructs a secure random number generator (RNG) implementing the default random number algorithm.
  This constructor traverses the list of registered security Providers, starting with the most preferred Provider. A new SecureRandom object encapsulating the SecureRandomSpi implementation from the first provider that supports a SecureRandom (RNG) algorithm is returned. If none of the providers support an RNG algorithm, then an implementation-specific default is returned.
  Note that the list of registered providers may be retrieved via the Security.getProviders() method.
  See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  External Specifications
  
  Java Security Standard Algorithm Names
- SecureRandom
  public SecureRandom(byte[] seed)
  
  Constructs a secure random number generator (RNG) implementing the default random number algorithm. The SecureRandom instance is seeded with the specified seed bytes.
  This constructor traverses the list of registered security Providers, starting with the most preferred Provider. A new SecureRandom object encapsulating the SecureRandomSpi implementation from the first provider that supports a SecureRandom (RNG) algorithm is returned. If none of the providers support an RNG algorithm, then an implementation-specific default is returned.
  Note that the list of registered providers may be retrieved via the Security.getProviders() method.
  See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  Parameters:
  
  seed - the seed.
  
  Throws:
  
  NullPointerException - if seed is null
  
  External Specifications
  
  Java Security Standard Algorithm Names
- SecureRandom
  
  protected SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider)
  
  Creates a SecureRandom object.
  
  Parameters:
  
  secureRandomSpi - the SecureRandom implementation.
  
  provider - the provider.
Method Details
- getInstance
  public static SecureRandom getInstance(String algorithm) throws NoSuchAlgorithmException
  
  Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm.
  This method traverses the list of registered security Providers, starting with the most preferred Provider. A new SecureRandom object encapsulating the SecureRandomSpi implementation from the first provider that supports the specified algorithm is returned.
  Note that the list of registered providers may be retrieved via the Security.getProviders() method.
  
  Implementation Note:
  
  The JDK Reference Implementation additionally uses the jdk.security.provider.preferred Security property to determine the preferred provider order for the specified algorithm. This may be different from the order of providers returned by Security.getProviders().
  
  Parameters:
  
  algorithm - the name of the RNG algorithm. See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  Returns:
  
  the new SecureRandom object
  
  Throws:
  
  NoSuchAlgorithmException - if no Provider supports a SecureRandomSpi implementation for the specified algorithm
  
  NullPointerException - if algorithm is null
  
  Since:
  
  1.2
  
  External Specifications
  
  Java Security Standard Algorithm Names
  
  See Also:
  
  Provider
- getInstance
  public static SecureRandom getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
  
  Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm.
  A new SecureRandom object encapsulating the SecureRandomSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.
  Note that the list of registered providers may be retrieved via the Security.getProviders() method.
  
  Parameters:
  
  algorithm - the name of the RNG algorithm. See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  provider - the name of the provider.
  
  Returns:
  
  the new SecureRandom object
  
  Throws:
  
  IllegalArgumentException - if the provider name is null or empty
  
  NoSuchAlgorithmException - if a SecureRandomSpi implementation for the specified algorithm is not available from the specified provider
  
  NoSuchProviderException - if the specified provider is not registered in the security provider list
  
  NullPointerException - if algorithm is null
  
  Since:
  
  1.2
  
  External Specifications
  
  Java Security Standard Algorithm Names
  
  See Also:
  
  Provider
- getInstance
  public static SecureRandom getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
  
  Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm.
  A new SecureRandom object encapsulating the SecureRandomSpi implementation from the specified provider is returned. Note that the specified provider does not have to be registered in the provider list.
  
  Parameters:
  
  algorithm - the name of the RNG algorithm. See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  provider - the provider.
  
  Returns:
  
  the new SecureRandom object
  
  Throws:
  
  IllegalArgumentException - if the specified provider is null
  
  NoSuchAlgorithmException - if a SecureRandomSpi implementation for the specified algorithm is not available from the specified Provider object
  
  NullPointerException - if algorithm is null
  
  Since:
  
  1.4
  
  External Specifications
  
  Java Security Standard Algorithm Names
  
  See Also:
  
  Provider
- getInstance
  public static SecureRandom getInstance(String algorithm, SecureRandomParameters params) throws NoSuchAlgorithmException
  
  Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm and supports the specified SecureRandomParameters request.
  This method traverses the list of registered security providers, starting with the most preferred provider. A new SecureRandom object encapsulating the SecureRandomSpi implementation from the first provider that supports the specified algorithm and the specified SecureRandomParameters is returned.
  Note that the list of registered providers may be retrieved via the Security.getProviders() method.
  
  Implementation Note:
  
  The JDK Reference Implementation additionally uses the jdk.security.provider.preferred property to determine the preferred provider order for the specified algorithm. This may be different from the order of providers returned by Security.getProviders().
  
  Parameters:
  
  algorithm - the name of the RNG algorithm. See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  params - the SecureRandomParameters the newly created SecureRandom object must support.
  
  Returns:
  
  the new SecureRandom object
  
  Throws:
  
  IllegalArgumentException - if the specified params is null
  
  NoSuchAlgorithmException - if no Provider supports a SecureRandomSpi implementation for the specified algorithm and parameters
  
  NullPointerException - if algorithm is null
  
  Since:
  
  9
  
  External Specifications
  
  Java Security Standard Algorithm Names
  
  See Also:
  
  Provider
- getInstance
  public static SecureRandom getInstance(String algorithm, SecureRandomParameters params, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
  
  Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm and supports the specified SecureRandomParameters request.
  A new SecureRandom object encapsulating the SecureRandomSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.
  Note that the list of registered providers may be retrieved via the Security.getProviders() method.
  
  Parameters:
  
  algorithm - the name of the RNG algorithm. See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  params - the SecureRandomParameters the newly created SecureRandom object must support.
  
  provider - the name of the provider.
  
  Returns:
  
  the new SecureRandom object
  
  Throws:
  
  IllegalArgumentException - if the provider name is null or empty, or params is null
  
  NoSuchAlgorithmException - if the specified provider does not support a SecureRandomSpi implementation for the specified algorithm and parameters
  
  NoSuchProviderException - if the specified provider is not registered in the security provider list
  
  NullPointerException - if algorithm is null
  
  Since:
  
  9
  
  External Specifications
  
  Java Security Standard Algorithm Names
  
  See Also:
  
  Provider
- getInstance
  public static SecureRandom getInstance(String algorithm, SecureRandomParameters params, Provider provider) throws NoSuchAlgorithmException
  
  Returns a SecureRandom object that implements the specified Random Number Generator (RNG) algorithm and supports the specified SecureRandomParameters request.
  A new SecureRandom object encapsulating the SecureRandomSpi implementation from the specified provider is returned. Note that the specified provider does not have to be registered in the provider list.
  
  Parameters:
  
  algorithm - the name of the RNG algorithm. See the SecureRandom section in the Java Security Standard Algorithm Names Specification for information about standard RNG algorithm names.
  
  params - the SecureRandomParameters the newly created SecureRandom object must support.
  
  provider - the provider.
  
  Returns:
  
  the new SecureRandom object
  
  Throws:
  
  IllegalArgumentException - if the specified provider or params is null
  
  NoSuchAlgorithmException - if the specified provider does not support a SecureRandomSpi implementation for the specified algorithm and parameters
  
  NullPointerException - if algorithm is null
  
  Since:
  
  9
  
  External Specifications
  
  Java Security Standard Algorithm Names
  
  See Also:
  
  Provider
- getProvider
  
  public final Provider getProvider()
  
  Returns the provider of this SecureRandom object.
  
  Returns:
  
  the provider of this SecureRandom object.
- getAlgorithm
  
  public String getAlgorithm()
  
  Returns the name of the algorithm implemented by this SecureRandom object.
  
  Returns:
  
  the name of the algorithm or unknown if the algorithm name cannot be determined.
  
  Since:
  
  1.5
- toString
  
  public String toString()
  
  Returns a Human-readable string representation of this SecureRandom.
  
  Overrides:
  
  toString in class Object
  
  Returns:
  
  the string representation
- getParameters
  public SecureRandomParameters getParameters()
  
  Returns the effective SecureRandomParameters for this SecureRandom instance.
  The returned value can be different from the SecureRandomParameters object passed into a getInstance method, but it cannot change during the lifetime of this SecureRandom object.
  A caller can use the returned value to find out what features this SecureRandom supports.
  
  Returns:
  
  the effective SecureRandomParameters parameters, or null if no parameters were used.
  
  Since:
  
  9
  
  See Also:
  
  SecureRandomSpi
- setSeed
  public void setSeed(byte[] seed)
  
  Reseeds this random object with the given seed. The seed supplements, rather than replaces, the existing seed. Thus, repeated calls are guaranteed never to reduce randomness.
  A PRNG SecureRandom will not seed itself automatically if setSeed is called before any nextBytes or reseed calls. The caller should make sure that the seed argument contains enough entropy for the security of this SecureRandom.
  
  Parameters:
  
  seed - the seed.
  
  Throws:
  
  NullPointerException - if seed is null
  
  See Also:
  
  getSeed(int)
- setSeed
  public void setSeed(long seed)
  
  Reseeds this random object, using the eight bytes contained in the given long seed. The given seed supplements, rather than replaces, the existing seed. Thus, repeated calls are guaranteed never to reduce randomness.
  A PRNG SecureRandom will not seed itself automatically if setSeed is called before any nextBytes or reseed calls. The caller should make sure that the seed argument contains enough entropy for the security of this SecureRandom.
  This method is defined for compatibility with java.util.Random.
  
  Overrides:
  
  setSeed in class Random
  
  Parameters:
  
  seed - the seed.
  
  See Also:
  
  getSeed(int)
- nextBytes
  
  public void nextBytes(byte[] bytes)
  
  Generates a user-specified number of random bytes.
  
  Specified by:
  
  nextBytes in interface RandomGenerator
  
  Overrides:
  
  nextBytes in class Random
  
  Parameters:
  
  bytes - the array to be filled in with random bytes.
  
  Throws:
  
  NullPointerException - if bytes is null
- nextBytes
  
  public void nextBytes(byte[] bytes, SecureRandomParameters params)
  
  Generates a user-specified number of random bytes with additional parameters.
  
  Parameters:
  
  bytes - the array to be filled in with random bytes
  
  params - additional parameters
  
  Throws:
  
  NullPointerException - if bytes is null
  
  UnsupportedOperationException - if the underlying provider implementation has not overridden this method
  
  IllegalArgumentException - if params is null, illegal or unsupported by this SecureRandom
  
  Since:
  
  9
- next
  
  protected final int next(int numBits)
  
  Generates an integer containing the user-specified number of pseudo-random bits (right justified, with leading zeros). This method overrides a java.util.Random method, and serves to provide a source of random bits to all the methods inherited from that class (for example, nextInt, nextLong, and nextFloat).
  
  Overrides:
  
  next in class Random
  
  Parameters:
  
  numBits - number of pseudo-random bits to be generated, where 0 <= numBits <= 32.
  
  Returns:
  
  an int containing the user-specified number of pseudo-random bits (right justified, with leading zeros).
- nextLong
  
  public long nextLong()
  
  Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. The general contract of nextLong is that one long value is pseudorandomly generated and returned.
  
  Specified by:
  
  nextLong in interface RandomGenerator
  
  Overrides:
  
  nextLong in class Random
  
  Returns:
  
  the next pseudorandom, uniformly distributed long value from this random number generator's sequence
- getSeed
  public static byte[] getSeed(int numBytes)
  
  Returns the given number of seed bytes, computed using the seed generation algorithm that this class uses to seed itself. This call may be used to seed other random number generators.
  This method is only included for backwards compatibility. The caller is encouraged to use one of the alternative getInstance methods to obtain a SecureRandom object, and then call the generateSeed method to obtain seed bytes from that object.
  
  Parameters:
  
  numBytes - the number of seed bytes to generate.
  
  Returns:
  
  the seed bytes.
  
  Throws:
  
  IllegalArgumentException - if numBytes is negative
  
  See Also:
  
  setSeed(byte[])
- generateSeed
  
  public byte[] generateSeed(int numBytes)
  
  Returns the given number of seed bytes, computed using the seed generation algorithm that this class uses to seed itself. This call may be used to seed other random number generators.
  
  Parameters:
  
  numBytes - the number of seed bytes to generate.
  
  Returns:
  
  the seed bytes.
  
  Throws:
  
  IllegalArgumentException - if numBytes is negative
- getInstanceStrong
  public static SecureRandom getInstanceStrong() throws NoSuchAlgorithmException
  
  Returns a SecureRandom object that was selected by using the algorithms/providers specified in the securerandom.strongAlgorithms Security property.
  Some situations require strong random values, such as when creating high-value/long-lived secrets like RSA public/private keys. To help guide applications in selecting a suitable strong SecureRandom implementation, Java distributions include a list of known strong SecureRandom implementations in the securerandom.strongAlgorithms Security property.
  Every implementation of the Java platform is required to support at least one strong SecureRandom implementation.
  
  Returns:
  
  a strong SecureRandom implementation as indicated by the securerandom.strongAlgorithms Security property
  
  Throws:
  
  NoSuchAlgorithmException - if no algorithm is available
  
  Since:
  
  1.8
  
  See Also:
  
  Security.getProperty(String)
- reseed
  
  public void reseed()
  
  Reseeds this SecureRandom with entropy input read from its entropy source.
  
  Throws:
  
  UnsupportedOperationException - if the underlying provider implementation has not overridden this method.
  
  Since:
  
  9
- reseed
  
  public void reseed(SecureRandomParameters params)
  
  Reseeds this SecureRandom with entropy input read from its entropy source with additional parameters.
  Note that entropy is obtained from an entropy source. While some data in params may contain entropy, its main usage is to provide diversity.
  
  Parameters:
  
  params - extra parameters
  
  Throws:
  
  UnsupportedOperationException - if the underlying provider implementation has not overridden this method.
  
  IllegalArgumentException - if params is null, illegal or unsupported by this SecureRandom
  
  Since:
  
  9

Class SecureRandom

Thread safety

Nested Class Summary

Nested classes/interfaces inherited from interface RandomGenerator

Constructor Summary

Method Summary

Methods inherited from class Random

Methods inherited from class Object

Methods inherited from interface RandomGenerator

Constructor Details

SecureRandom

SecureRandom

SecureRandom

Method Details

getInstance

getInstance

getInstance

getInstance

getInstance

getInstance

getProvider

getAlgorithm

toString

getParameters

setSeed

setSeed

nextBytes

nextBytes

next

nextLong

getSeed

generateSeed

getInstanceStrong

reseed

reseed