聊聊java的java.security.egd

最新推荐文章于 2025-10-27 14:51:13 发布

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最新推荐文章于 2025-10-27 14:51:13 发布 · 1.4k 阅读

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#java #开发语言

文章详细解释了Java中java.security.egd的作用，它在随机数生成时的优先级以及如何从不同的源（如/dev/random、/dev/urandom）获取高熵随机数。讨论了不同类（如SeedGenerator、NativeSeedGenerator和SecureRandomSpi）之间的关系及其在JEP123中的角色。

序

本文主要研究一下java的java.security.egd

SunEntries

/Library/Java/JavaVirtualMachines/temurin-8.jdk/Contents/Home/src.zip!/sun/security/provider/SunEntries.java

    // name of the *System* property, takes precedence over PROP_RNDSOURCE
    private final static String PROP_EGD = "java.security.egd";
    // name of the *Security* property
    private final static String PROP_RNDSOURCE = "securerandom.source";

    final static String URL_DEV_RANDOM = "file:/dev/random";
    final static String URL_DEV_URANDOM = "file:/dev/urandom";

    private static final String seedSource;

    static {
        seedSource = AccessController.doPrivileged(
                new PrivilegedAction<String>() {

            @Override
            public String run() {
                String egdSource = System.getProperty(PROP_EGD, "");
                if (egdSource.length() != 0) {
                    return egdSource;
                }
                egdSource = Security.getProperty(PROP_RNDSOURCE);
                if (egdSource == null) {
                    return "";
                }
                return egdSource;
            }
        });
    }