概念
JAVA使用keystore文件來存儲所有KEY，keystore文件可以存放多個KEY，訪問它需要密碼。
下面我介紹下如何將用OpenSSL做自簽名的證書一文中介紹的OpenSSL產生的KEY與JAVA的KEY轉換后使用，從而達到JAVA與OpenSSL通信的目的。


用OpenSSL生成CA根證書，即(P1,V1)
此步驟參見用OpenSSL做自簽名的證書一文


在JAVA環境下生成自己的KEY，即(P2,V2)

keytool -genkey -alias clientapp -keystore mycerts

注意：這里會提示輸入訪問keystore的密碼，以及組織、城市、省份，一定要與CA根證書的一致，否則不能被CA簽名。


從keystore中導出public key，即P2

keytool -keystore mycerts -certreq -alias clientapp -file clientapp.crs


用CA根證書為這個public key進行簽名，即用V1給P2加密

openssl ca -out clientapp.pem -config ./openssl.cnf -infiles?clientapp.crs
?

轉換PEM到DER格式

openssl x509 -in clientapp.pem -out clientapp.der -outform DER


導入CA證書，即P1

keytool -keystore mycerts -alias systemca -import -file cacert.pem


導入用戶證書，即被V1加密過的P2

keytool -keystore mycerts -alias clientapp -import -file clientapp.der

注意：這里一定要先導入CA證書再導入用戶證書，否則會報錯。

現在我們就生成了JAVA服務器使用的所有KEY了，在程序中將mycerts這個keystore導入就可以了。
如果客戶端是使用OpenSSL的程序，那么用CA證書cacert.pem就能正常通信了，如果也是JAVA程序，那么我們需要將CA證書也轉換成keystore：

keytool -import -keystore clikeystore -import -trustcacerts -file cacert.pem

生成的clikeystore供JAVA客戶端使用，就能通信。


再附上SVR和CLI的JAVA程序，我已經用上面的KEY都測試通過：
SVR端：

import ?java.io. * ;
import ?java.net. * ;
import ?com.sun.net.ssl.KeyManagerFactory;
import ?com.sun.net.ssl.KeyManager;
import ?com.sun.net.ssl.TrustManagerFactory;
import ?com.sun.net.ssl.TrustManager;
import ?com.sun.net.ssl.SSLContext;
import ?javax.net.ServerSocketFactory;
import ?java.security.KeyStore;

public ? class ?svr? implements ?Runnable {
??
?? public ? static ? final ? int ?PORT? = ? 5555 ;
?? public ? static ? final ?String?HOST? = ? " localhost " ;
?? public ? static ? final ?String?QUESTION? = ? " Knock,?knock. " ;
?? public ? static ? final ?String?ANSWER? = ? " Who's?there? " ;

?? // ?The?new?constants?that?are?used?during?setup.
?? public ? static ? final ?String?KEYSTORE_FILE? = ? " mycerts " ; // "server_keystore";
?? public ? static ? final ?String?ALGORITHM? = ? " sunx509 " ;
?? public ? static ? final ?String?PASSWORD? = ? " churchillobjects " ;
??
?? public ? static ? void ?main(String[]?args) {
???? new ?Thread( new ?svr()).start();
??}
??
?? public ? void ?run() {
????ServerSocket?ss? = ? null ;
???? try ? {

?????? // ?Local?references?used?for?clarity.?Their?presence
?????? // ?here?is?part?of?the?reason?we?need?to?import
?????? // ?so?many?classes.
??????KeyManagerFactory?kmf;
??????KeyManager[]?km;
??????KeyStore?ks;
??????TrustManagerFactory?tmf;
??????TrustManager[]?tm;
??????SSLContext?sslc;
??????
?????? // ?Create?a?keystore?that?will?read?the?JKS?(Java?KeyStore)
?????? // ?file?format?which?was?created?by?the?keytool?utility.
??????ks? = ?KeyStore.getInstance( " JKS " );
??????
?????? // ?Load?the?keystore?object?with?the?binary?keystore?file?and
?????? // ?a?byte?array?representing?its?password.
??????ks.load( new ?FileInputStream(KEYSTORE_FILE),?PASSWORD.toCharArray());
??????
?????? // ?Gives?us?a?factory?for?key?managers?that?will?let
?????? // ?us?handle?the?asymetric?keys?we?created?earlier.
??????kmf? = ?KeyManagerFactory.getInstance(ALGORITHM);

?????? // ?Initialize?the?key?manager?factory?with?the?keystore?object,
?????? // ?again?using?the?same?password?for?security?since?it?is?going?to
?????? // ?access?the?private?key.
??????kmf.init(ks,?PASSWORD.toCharArray());
??????
?????? // ?Now?we?can?get?the?key?managers?from?the?factory,?since?it?knows
?????? // ?what?type?we?are?using?now.
??????km? = ?kmf.getKeyManagers();
??????
?????? // ?Next,?create?a?trust?manager?factory?using?the?same?algorithm.
?????? // ?This?is?to?avoid?using?the?certificates?in?cacerts?that
?????? // ?represent?an?authentication?security?risk.
??????tmf? = ?TrustManagerFactory.getInstance(ALGORITHM);
??????
?????? // ?then?initialize?it?with?the?keystore?object.?This?time?we?don't
?????? // ?need?the?keystore?password.?This?is?because?trusted?certificates
?????? // ?are?not?a?sensitive?element?in?the?keystore,?unlike?the
?????? // ?private?keys.
??????tmf.init(ks);
??????
?????? // ?Once?that's?initialized,?get?the?trust?managers?from?the?factory.
??????tm? = ?tmf.getTrustManagers();
??????
?????? // ?Almost?done,?we?need?a?context?object?that?will?get?our
?????? // ?server?socket?factory.?We?specify?TLS?to?indicate?that?we?will
?????? // ?need?a?server?socket?factory?that?supports?SSL.
??????sslc? = ?SSLContext.getInstance( " TLS " );
??????
?????? // ?Initialize?the?context?object?with?the?key?managers?and?trust
?????? // ?managers?we?got?earlier.?The?third?parameter?is?an?optional
?????? // ?SecureRandom?object.?By?passing?in?null,?we?are?letting?the
?????? // ?context?object?create?its?own.
??????sslc.init(km,?tm,? null );
??????
?????? // ?Finally,?we?get?the?ordinary-looking?server?socket?factory
?????? // ?from?the?context?object.
??????ServerSocketFactory?ssf? = ?sslc.getServerSocketFactory();
??????
?????? // ?From?the?factory,?we?simply?ask?for?an?ordinary-looking
?????? // ?server?socket?on?the?port?we?wish.
??????ss? = ?ssf.createServerSocket(PORT);

??????listen(ss);
????}
???? catch (Exception?e) {
??????e.printStackTrace();
????}
???? finally {
?????? if (ss != null ) {
???????? try {
??????????ss.close();
????????}
???????? catch (IOException?e) {
?????????? // ?oh,?well
????????}
??????}
??????System.exit( 0 );
????}
??}
??
?? static ? void ?listen(ServerSocket?ss)? throws ?Exception {
????System.out.println( " Ready?for?connections. " );
???? while ( true ) {
??????Socket?s? = ?ss.accept();
??????BufferedWriter?bw? = ? new ?BufferedWriter(
???????? new ?OutputStreamWriter(s.getOutputStream()));
??????BufferedReader?br? = ? new ?BufferedReader(
???????? new ?InputStreamReader(s.getInputStream()));
??????String?q? = ?br.readLine();
?????? if ( ! QUESTION.equals(q)) {
???????? throw ? new ?RuntimeException( " Wrong?question:?\ "" ?+?q?+? " \ "" );
??????}
??????System.out.println( " Question:?\ "" ?+?q?+? " \ "" );
??????bw.write(ANSWER + " \n " );
??????bw.flush();
??????s.close();
????}
??}
}

CLI端程序：

import ?java.io. * ;
import ?java.net. * ;
import ?com.sun.net.ssl.KeyManagerFactory;
import ?com.sun.net.ssl.TrustManagerFactory;
import ?com.sun.net.ssl.SSLContext;
import ?java.security.KeyStore;
import ?javax.net.SocketFactory;

public ? class ?cli? implements ?Runnable {
??
?? public ? static ? final ? int ?PORT? = ? 5555 ;
?? public ? static ? final ?String?HOST? = ? " localhost " ;
?? public ? static ? final ?String?KEYSTORE_FILE? = ? " clikeystore " ; // "client_keystore";
?? public ? static ? final ?String?ALGORITHM? = ? " sunx509 " ;
?? public ? static ? final ?String?PASSWORD? = ? " churchillobjects " ;
?? public ? static ? final ?String?QUESTION? = ? " Knock,?knock. " ;
?? public ? static ? final ?String?ANSWER? = ? " Who's?there? " ;
??
?? public ? static ? void ?main(String[]?args) {
???? new ?Thread( new ?cli()).start();
??}
??
?? public ? void ?run() {
????Socket?socket? = ? null ;
???? try {
??????KeyManagerFactory?kmf;
??????KeyStore?ks;
??????TrustManagerFactory?tmf;
??????SSLContext?sslc;

??????kmf? = ?KeyManagerFactory.getInstance(ALGORITHM);
??????ks? = ?KeyStore.getInstance(? " JKS " ?);
??????ks.load( new ?FileInputStream(KEYSTORE_FILE),?PASSWORD.toCharArray());
??????kmf.init(ks,?PASSWORD.toCharArray());
??????tmf? = ?TrustManagerFactory.getInstance(ALGORITHM);
??????tmf.init(ks);
??????sslc? = ?SSLContext.getInstance( " TLS " );
??????sslc.init(kmf.getKeyManagers(),?tmf.getTrustManagers(),? null );

?????? // ?The?process?is?different?from?here?on?the?client.?Instead?of
?????? // ?getting?a?ServerSocketFactory,?we?ask?for?a?SocketFactory?from
?????? // ?the?SSL?context.
??????SocketFactory?sf? = ?sslc.getSocketFactory();

?????? // ?Then?we?get?the?socket?from?the?factory?and?treat?it
?????? // ?as?if?it?were?a?standard?(plain)?socket.
??????socket? = ?sf.createSocket(HOST,?PORT);
????
??????doQuery(socket);
????}
???? catch (Exception?e) {
??????e.printStackTrace();
????}
???? finally {
?????? if (socket != null ) {
???????? try {
??????????socket.close();
????????}
???????? catch (IOException?e) {
?????????? // ?oh,?well
????????}
??????}
??????System.exit( 0 );
????}
??}

?? private ? void ?doQuery(Socket?s)? throws ?Exception {
????BufferedWriter?bw? = ? new ?BufferedWriter( new ?OutputStreamWriter(s.getOutputStream()));
????BufferedReader?br? = ? new ?BufferedReader( new ?InputStreamReader(s.getInputStream()));
????bw.write(QUESTION + " \n " );
????bw.flush();
????String?response? = ?br.readLine();
???? if ( ! ANSWER.equals(response)) {
?????? throw ? new ?RuntimeException( " Wrong?answer:?\ "" ?+?response?+? " \ "" );
????}
????System.out.println( " Got?the?right?answer:?\ "" ?+?response?+? " \ "" );
??}
}

以上方法主要參考了如下兩個網頁：

http://www.churchillobjects.com/c/11201g.html

http://mark.foster.cc/kb/openssl-keytool.html