是否可以在PHP中预测rand(0,10)? [英] Is it possible to predict rand(0,10) in PHP?

问题描述

我有一个脚本，可以在PHP中使用rand函数.现在，我读了一些鬼故事，它们确实很容易预测这些结果.从客户端这可能吗?

I have a script where I use the rand function in PHP. Now I read some ghost stories that its real easy to predict those outcomes. Is this possible from the client-side?

例如，假设我们有一个rand(0,10).可以预测下一个数字吗?

For example, let say we have a rand(0,10). Is it possible to predict the next number?

推荐答案

rand()函数返回伪随机数. 这并不意味着可以预测next数. 但是，此图像可以解释单词pseudorandom

rand() function returns a pseudorandom number . This does NOT mean that the next number can be predicted. However this image can explain the concept of word pseudorandom

您可以阅读文章

图像是通过Windows系统上具有rand功能的简单循环生成的.

the image is generated from a simple loop with rand function on windows system.

header("Content-type: image/png");
$im = imagecreatetruecolor(512, 512) or die("Cannot Initialize new GD image stream");
$white = imagecolorallocate($im, 255, 255, 255);
for ($y = 0; $y < 512; $y++) {
    for ($x = 0; $x < 512; $x++) {
        if (rand(0, 1)) {
            imagesetpixel($im, $x, $y, $white); 
        } 
    } 
} 
imagepng($im); imagedestroy($im);

不是那么随机，真的吗?但是现在您知道了...您可以预测下一个数字了吗?

It's not so random, really? But now that you know it... you can predict the next number?

真随机数生成器(TRNG)与伪随机数生成器(PRNG)之间的区别在于，TRNG使用不可预测的物理方式生成数字(例如大气噪声)，而PRNG使用数学算法(完全由计算机生成)

The difference between true random number generators (TRNGs) and pseudo-random number generators (PRNGs) is that TRNGs use an unpredictable physical means to generate numbers (like atmospheric noise), and PRNGs use mathematical algorithms (completely computer-generated)

[...]

很少有PRNG会产生这种明显的视觉图案，恰好碰巧是语言(PHP)，操作系统(Windows)和函数(rand())的真正糟糕组合.

Not many PRNGs will produce an obvious visual pattern like this, it just so happens to be a really bad combination of language (PHP), operating system (Windows), and function (rand()).

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