JRE 8 rt.jar is the JAR file for JRE 8 RT (Runtime) libraries. JRE (Java Runtime) 8 is the runtime environment included in JDK 8. JRE 8 rt.jar libraries are divided into 6 packages:

com.* - Internal Oracle and Sun Microsystems libraries
java.* - Standard Java API libraries.
javax.* - Extended Java API libraries.
jdk.* -  JDK supporting libraries.
org.* - Third party libraries.
sun.* - Old libraries developed by Sun Microsystems.

JAR File Information:

Directory of C:\fyicenter\jdk-1.8.0_191\jre\lib
      63,596,151 rt.jar

Here is the list of Java classes of the java.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ java/security/spec/package-info.java

/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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/**
 * Provides classes and interfaces for key specifications and algorithm
 * parameter specifications.
 *
 * <p>A key specification is a transparent representation of the key material
 * that constitutes a key. A key may be specified in an algorithm-specific
 * way, or in an algorithm-independent encoding format (such as ASN.1).
 * This package contains key specifications for DSA public and private keys,
 * RSA public and private keys, PKCS #8 private keys in DER-encoded format,
 * and X.509 public and private keys in DER-encoded format.
 *
 * <p>An algorithm parameter specification is a transparent representation
 * of the sets of parameters used with an algorithm. This package contains
 * an algorithm parameter specification for parameters used with the
 * DSA algorithm.
 *
 * <h2>Package Specification</h2>
 *
 * <ul>
 *   <li>PKCS #1: RSA Encryption Standard, Version 1.5, November 1993</li>
 *   <li>PKCS #8: Private-Key Information Syntax Standard,
 *     Version 1.2, November 1993</li>
 *   <li>Federal Information Processing Standards Publication (FIPS PUB) 186:
 *     Digital Signature Standard (DSS)</li>
 * </ul>
 *
 * <h2>Related Documentation</h2>
 *
 * For documentation that includes information about algorithm parameter
 * and key specifications, please see:
 * <ul>
 *   <li>
 *     <a href=
 *       "{@docRoot}/../technotes/guides/security/crypto/CryptoSpec.html">
 *       <b>Java&trade;
 *       Cryptography Architecture API Specification and Reference
 *       </b></a></li>
 *   <li>
 *     <a href=
 *       "{@docRoot}/../technotes/guides/security/crypto/HowToImplAProvider.html">
 *       <b>How to Implement a Provider for the
 *       Java&trade; Cryptography Architecture
 *       </b></a></li>
 * </ul>
 *
 * @since 1.2
 */
package java.security.spec;

⏎ java/security/spec/package-info.java

Or download all of them as a single archive file:

File name: jre-rt-java-1.8.0_191-src.zip
File size: 6664831 bytes
Release date: 2018-10-28
Download 

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