jdk.security.SecureRandom — clojure-interop/java.security 1.0.5

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 1750: Randomness Recommendations for Security.

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

 SecureRandom random = new SecureRandom();

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

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 method to generate a given number of seed bytes (to seed other random number generators, for example):

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

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

*get-instance clj

(*get-instance algorithm)

(*get-instance algorithm provider)

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.

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 the SecureRandom section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard RNG algorithm names. - java.lang.String provider - the name of the provider. - java.lang.String

returns: the new SecureRandom object. - java.security.SecureRandom

throws: java.security.NoSuchAlgorithmException - if a SecureRandomSpi implementation for the specified algorithm is not available from the specified provider.

*get-instance-strong clj

(*get-instance-strong)

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 - java.security.SecureRandom

throws: java.security.NoSuchAlgorithmException - if no algorithm is available

*get-seed clj

(*get-seed num-bytes)

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.

num-bytes - the number of seed bytes to generate. - int

returns: the seed bytes. - byte[]

->secure-random clj

(->secure-random)

(->secure-random seed)

Constructor.

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 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 the SecureRandom section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard RNG algorithm names.

seed - the seed. - byte[]

generate-seed clj

(generate-seed this num-bytes)

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.

num-bytes - the number of seed bytes to generate. - int

returns: the seed bytes. - byte[]

get-algorithm clj

(get-algorithm this)

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. - java.lang.String

get-provider clj

(get-provider this)

Returns the provider of this SecureRandom object.

returns: the provider of this SecureRandom object. - java.security.Provider

next-bytes clj

(next-bytes this bytes)

Generates a user-specified number of random 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. - byte[]

set-seed clj

(set-seed this seed)

Reseeds this random object. The given seed supplements, rather than replaces, the existing seed. Thus, repeated calls are guaranteed never to reduce randomness.

seed - the seed. - byte[]