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Programming-Idioms

  • Perl
  • Go

Idiom #318 Cryptographically secure random number

Assign to the integer x a random number between 0 and 17 (inclusive), from a crypto secure random number generator.

import "crypto/rand"
import "math/big"
bi, err := rand.Int(rand.Reader, big.NewInt(18))
x := int(bi.Int64())

crypto/rand.Int works with big ints, and the secure RNG Reader.
use Math::Random::Secure qw(irand);
my $x = irand(17);

Perl's built-in rand function is not cryptographically secure. But there are several CPAN modules that can do the job, such as Math::Random::Secure.
irand returns a 32-bit integer.
use Math::Random::Secure qw(rand);
my $x = int(rand(17));

This is slower than irand.
$x = random_int(0, 17)

This requires PHP >= 7
New implementation...
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programming-idioms.org 
bi, err := rand.Int(rand.Reader, big.NewInt(18))
x := int(bi.Int64())
my $x = irand(17);
my $x = int(rand(17));
$x = random_int(0, 17)
x = secrets.choice(range(0, 18))

x = secrets.randbelow(18)
x = SecureRandom.rand(0..17)
let mut rng = rand::thread_rng();
let x = rng.gen_range(0..18);