Uh ... sorry to be a wet blanket, but it doesn’t help on my system (Strawberry Perl, Windows 8.1, 64-bit):

19:01 >perl -e "srand 42; print sort {4-rand 9} split //, 'ts aroMrhir
+sae C tll!!ym';"
l ttyaMeos  arrCsrihm!!l
19:01 >perl -e "use Math::Random::Mt qw[rand srand]; srand 42; print s
+ort {4-rand 9} split //, 'ts aroMrhirsae C tll!!ym';"
l ttyaMeos  arrCsrihm!!l
19:01 >perl -v

This is perl 5, version 20, subversion 0 (v5.20.0) built for MSWin32-x
+64-multi-thread
[download]

:-(

. sorry to be a wet blanket, but it doesn’t help on my system (Strawberry Perl, Windows 8.1, 64-bit):

Of course not. It would need to have been used by the author when constructing the obfu.

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

l ttyaMeos arrCsrihm!!l

With my perls, the original one-liner works as intended for 5.8.8 up to and including 5.18.0.
But with 5.20.0 I get the same as you.

The srand documentation contains this:

However, there are a few situations where programs are likely to
want to call "srand". One is for generating predictable results,
generally for testing or debugging. There, you use
"srand($seed)", with the same $seed each time.
[download]

That suggests to me that srand(42) should produce identical results whenever it is called.
I can't find anything in the docs that indicate there have been changes to srand - grepping 5.20.0 perldelta for srand produced no hits.

However, there *is* mention (in perldelta) of changes to rand with 5.20, and I guess that if the rand implementation has changed then the same seed will no longer yield same results.
I do think that the breakage of srand($seed) between 5.20 and earlier perls should have been spelled out in the srand documentation ... probably worth a bug report from someone who cares.

Cheers,
Rob

I do think that the breakage of srand($seed) between 5.20 and earlier perls should have been spelled out in the srand documentation ... probably worth a bug report from someone who cares.

As documented in the 5.20 delta:

rand now uses a consistent random number generator Previously perl would use a platform specific random number generator, varying between the libc rand(), random() or drand48(). This meant that the quality of perl's random numbers would vary from platform to platform, from the 15 bits of rand() on Windows to 48-bits on POSIX platforms such as Linux with drand48(). Perl now uses its own internal drand48() implementation on all platforms. This does not make perl's rand cryptographically secure.

The effect of srand was platform specific. Ie different between Windows & *nix. And that is the cause of the failures for the obfu.

From 5.20 on, that problem goes away because of the built-in rand/srand rather inheriting them from the platform C compiler implementation.

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.