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JavaTM 2 Platform Std. Ed. v1.6.0
java.security
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Constructor Summary | |
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SecureRandom()
Constructs a secure random number generator (RNG) implementing the default random number algorithm. |
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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 | |
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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,
Provider provider)
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. |
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 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 |
setSeed(byte[] seed)
Reseeds this random object. |
void |
setSeed(long seed)
Reseeds this random object, using the eight bytes contained in the given long seed . |
Methods inherited from class java.util.Random |
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nextBoolean, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public SecureRandom()
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 a 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 Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard RNG algorithm names.
The returned SecureRandom object has not been seeded. To seed the
returned object, call the setSeed
method.
If setSeed
is not called, the first call to
nextBytes
will force the SecureRandom object to seed itself.
This self-seeding will not occur if setSeed
was
previously called.
public SecureRandom(byte[] seed)
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 a 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 Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard RNG algorithm names.
seed
- the seed.protected SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider)
secureRandomSpi
- the SecureRandom implementation.provider
- the provider.Method Detail |
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public static SecureRandom getInstance(String algorithm) throws NoSuchAlgorithmException
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.
The returned SecureRandom object has not been seeded. To seed the
returned object, call the setSeed
method.
If setSeed
is not called, the first call to
nextBytes
will force the SecureRandom object to seed itself.
This self-seeding will not occur if setSeed
was
previously called.
algorithm
- the name of the RNG algorithm.
See Appendix A in the
Java Cryptography Architecture API Specification & Reference
for information about standard RNG algorithm names.
NoSuchAlgorithmException
- if no Provider supports a
SecureRandomSpi implementation for the
specified algorithm.Provider
public static SecureRandom getInstance(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
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.
The returned SecureRandom object has not been seeded. To seed the
returned object, call the setSeed
method.
If setSeed
is not called, the first call to
nextBytes
will force the SecureRandom object to seed itself.
This self-seeding will not occur if setSeed
was
previously called.
algorithm
- the name of the RNG algorithm.
See Appendix A in the
Java Cryptography Architecture API Specification & Reference
for information about standard RNG algorithm names.provider
- the name of the provider.
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.
IllegalArgumentException
- if the provider name is null
or empty.Provider
public static SecureRandom getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
A new SecureRandom object encapsulating the SecureRandomSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
The returned SecureRandom object has not been seeded. To seed the
returned object, call the setSeed
method.
If setSeed
is not called, the first call to
nextBytes
will force the SecureRandom object to seed itself.
This self-seeding will not occur if setSeed
was
previously called.
algorithm
- the name of the RNG algorithm.
See Appendix A in the
Java Cryptography Architecture API Specification & Reference
for information about standard RNG algorithm names.provider
- the provider.
NoSuchAlgorithmException
- if a SecureRandomSpi
implementation for the specified algorithm is not available
from the specified Provider object.
IllegalArgumentException
- if the specified provider is null.Provider
public final Provider getProvider()
public String getAlgorithm()
unknown
if the algorithm name cannot be determined.public void setSeed(byte[] seed)
seed
- the seed.getSeed(int)
public void setSeed(long seed)
long seed
. The given seed supplements,
rather than replaces, the existing seed. Thus, repeated calls
are guaranteed never to reduce randomness.
This method is defined for compatibility with
java.util.Random
.
seed
- the seed.getSeed(int)
public void nextBytes(byte[] bytes)
If a call to setSeed
had not occurred previously,
the first call to this method forces this SecureRandom object
to seed itself. This self-seeding will not occur if
setSeed
was previously called.
bytes
- the array to be filled in with random bytes.protected final int next(int numBits)
java.util.Random
method, and serves
to provide a source of random bits to all of the methods inherited
from that class (for example, nextInt
,
nextLong
, and nextFloat
).
numBits
- number of pseudo-random bits to be generated, where
0 <= numBits
<= 32.
int
containing the user-specified number
of pseudo-random bits (right justified, with leading zeros).public static byte[] getSeed(int numBytes)
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.
numBytes
- the number of seed bytes to generate.
setSeed(byte[])
public byte[] generateSeed(int numBytes)
numBytes
- the number of seed bytes to generate.