# Class SecureRandom

java.lang.Object
com.codename1.security.SecureRandom

public final class SecureRandom extends Object

Cryptographically secure random number generator. Delegates to the platform's native CSPRNG (`/dev/urandom` on Unix-style systems, the Windows BCryptGenRandom on Windows, `SecRandomCopyBytes` on iOS, the hardware RNG on devices that expose one).

Use this class -- not `java.util.Random` or `Math.random()` -- whenever the output is going to be used as a key, nonce, salt, session token, password reset code or any other security-sensitive value.

##### Example

    byte[] iv = SecureRandom.bytes(12); // AES-GCM nonce
    int code  = SecureRandom.intBelow(1_000_000); // 6-digit code

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static byte[]`
  `bytes(int length)`
  Returns a fresh `length`-byte array filled with secure random bytes.
  `static void`
  `fill(byte[] out)`
  Fills `out` with secure random bytes.
  `static int`
  `intBelow(int bound)`
  Returns a uniformly distributed random int in `[0, bound)`.
  `static long`
  `longBelow(long bound)`
  Returns a uniformly distributed random long in `[0, bound)`.

  ### Methods inherited from class Object

  `clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Method Details

  - ### bytes

    public static byte[] bytes(int length)
    Returns a fresh `length`-byte array filled with secure random bytes.

  - ### fill

    public static void fill(byte[] out)
    Fills `out` with secure random bytes.

  - ### intBelow

    public static int intBelow(int bound)
    Returns a uniformly distributed random int in `[0, bound)`. `bound` must be positive.

  - ### longBelow

    public static long longBelow(long bound)
    Returns a uniformly distributed random long in `[0, bound)`. `bound` must be positive.