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https://issues.apache.org/jira/browse/MATH-701?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13143944#comment-13143944
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Gilles edited comment on MATH-701 at 11/4/11 1:00 PM:
------------------------------------------------------
* From Harmony's implementation of "java.util.Random":
{code}
public Random() {
setSeed(System.currentTimeMillis() + hashCode());
}
{code}
* I'd also prefer setting both RNGs at construction.
A user would have to write
{code}
SecureRandom secRand = SecureRandom.getInstance(algorithm, provider);
{code}
in his application's code, and that would make it clearer for him why and how
an exception can be generated (and that CM's code is not the cause of it).
* I also favour a new "SecureRandomDataImpl" as a subclass of "RandomDataImpl";
the constructor would be something like:
{code}
public SecureRandomDataImpl(SecureRandom rng) {
super(rng);
}
{code}
This would ensure that _all_ the {{next...}} methods use a secure RNG, whereas
currently only some of the accessors have a secure alternative (e.g.
"nextGaussian" is not using "secRand"). This would be less confusing without
requiring long explanations...
was (Author: erans):
* Harmony:
{code}
seed = System.currentTimeMillis() + hashCode();
{code}
* I'd also prefer setting both RNGs at construction.
A user would have to write
{code}
SecureRandom secRand = SecureRandom.getInstance(algorithm, provider);
{code}
in his application's code, and that would make it clearer for him why and how
an exception can be generated (and that CM's code is not the cause of it).
* I also favour a new "SecureRandomDataImpl" as a subclass of "RandomDataImpl";
the constructor would be something like:
{code}
public SecureRandomDataImpl(SecureRandom rng) {
super(rng);
}
{code}
This would ensure that _all_ the {{next...}} methods use a secure RNG, whereas
currently only some of the accessors have a secure alternative (e.g.
"nextGaussian" is not using "secRand"). This would be less confusing without
requiring long explanations...
> Seeding a default RNG
> ---------------------
>
> Key: MATH-701
> URL: https://issues.apache.org/jira/browse/MATH-701
> Project: Commons Math
> Issue Type: Bug
> Reporter: Gilles
> Assignee: Gilles
> Fix For: 3.0
>
>
> In "RandomDataImpl":
> {code}
> private RandomGenerator getRan() {
> if (rand == null) {
> rand = new JDKRandomGenerator();
> rand.setSeed(System.currentTimeMillis());
> }
> return rand;
> }
> {code}
> The conditional branch is used by "sample()" in
> "AbstractContinuousDistribution".
> When several "...Distribution" objects are instantiated in a short time
> interval, they are seeded with the same value.
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