如何使用ISAAC用C [英] How to use ISAAC in C

问题描述

我下载isaac64从这里和我有一些问题与使用情况。
我不得不发表评论code的一部分在isaac64.c becouse它包含了主要的功能。但我不能用它......我不能正确初始化，并得到随机数，你能帮帮我吗？我couldn'y发现的例子。

I downloaded isaac64 from here and I have some problem with usage. I had to comment a part of code in isaac64.c becouse it contained main function. But I can't use it... I can't properly initialize it and get random number, can you help me? I couldn'y found any example.

    randinit(TRUE); 
    for(i=0;i<10;i++){
    printf("%lx\n",rand());
    }

我每次运行此code时，我得到了相同的值。我不知道如何设置种子。

each time I run this code I get the same values. I don't know how to set seed.

推荐答案

这以撒的版本是参考实现，这意味着它的意图被称为，但不是特别用户友好的或准备投产。有任何数目的<一href=\"https://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator#Special_designs\"相对=nofollow>加密安全随机数发生器的在C，它更容易使用。特别是，简单的读从的/ dev /随机字节是在大多数操作系统上不够好

This version of ISAAC is a "reference implementation" meaning it's intended to be referred to but isn't particularly user friendly or ready for production. There are any number of cryptographically secure random number generators in C that are easier to use. In particular, simply reading bytes from /dev/random is good enough on most operating systems.

的主函数演示如何使用图书馆。它已经与 #IFDEF 取值注释掉。我发现周围使用ISAAC Perl的包装为一个指南也有帮助。

The main function demonstrates how to use the library. It's already commented out with #ifdefs. I've found using the Perl wrapper around ISAAC as a guide also helps.

int main()
{
    /* Initialize the structure to 0 */
    randctx ctx;
    ctx.randa = ctx.randb = ctx.randc = (ub4)0;

    /* Initialize the seed */
    for (ub4 i=0; i<256; ++i) {
        ctx.randrsl[i] = i;
    }

    /* Initialize the random numbers from the seed */
    randinit(&ctx, TRUE);

    /* Print 10 pseudo random numbers */
    for(int i=0; i<10; i++) {
        printf("%.8lx\n", rand(&ctx));
    }
}

您必须提供种子 或熵。如果提供了相同的种子，你会得到相同的结果。这就是为什么ISAAC是的伪的随机数生成器，它只能使更多的随机数字似乎从现有的随意性。有一个的从哪里数学::随机得到你的种子讨论： ：ISAAC

You must supply the seed, or "entropy". If you supply the same seed you will get the same result. This is why ISAAC is a psuedo random number generator, it can only make more random-seeming numbers out of existing randomness. There is a discussion of where to get your seed from in Math::Random::ISAAC.

如果这是你新的概念，如果这个生产code，我的强烈建议您只需从的/ dev /随机读 。这ISAAC实现是非常粗糙，密码学的很容易的得到错误的。 的/ dev /随机已照顾所有这一切都为你。

If these are new concepts to you, and if this for production code, I would strongly recommend you simply read from /dev/random. This ISAAC implementation is very rough and cryptography is very easy to get wrong. /dev/random has already taken care of all of this for you.

如果你必须使用自己的伪随机库，使用公实施和记录库类似的 OpenSSL的。

If you must use your own pseudo-random library, use a well-implemented and documented library like OpenSSL.

如果你打算用这个经历，我会建议调整的从Perl中的code的包装器版本因为至少笔者已经清理它被释放值得的。

If you're going to go through with this, I would recommend adapting the version of the code from the Perl wrapper because at least the author has cleaned it up to be release worthy.

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