java - JavaMail 中的错误：PKIX 路径构建失败，无法找到请求目标的有效证书路径

Question

我正在尝试在 android 中构建一个电子邮件客户端应用程序，现在我想配置 javaMail 部分。

我正在尝试与 imap 服务器建立连接，但我的代码有问题。这是我的代码：

package mailpackage;

import java.util.Properties;

import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Store;

public class Connection implements Runnable
{
    boolean done;

    public Connection()
    {
        this.done=false;
    }

    @Override
    public void run()
    {
        System.out.println("Hello from Connection Thread!");
        while(!done)
        {
            String host = "myhost";// change accordingly
            String mailStoreType = "imap";
            String username = "myusername";// change accordingly
            String password = "mypasswd";// change accordingly

            check(host, mailStoreType, username, password);

        }
    }

    public static void receiveEmail(String host, String storeType,  String username, String password)
{
    try
    {
        Properties properties = new Properties();  
        properties.put("mail.imap.com", host);  
        properties.put("mail.imap.starttls.enable","true");
        properties.put("mail.imap.auth", "true");  // If you need to authenticate

        // Use the following if you need SSL
        properties.put("mail.imap.socketFactory.port", 993);
        properties.put("mail.imap.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        properties.put("mail.imap.socketFactory.fallback", "false");

        Session emailSession = Session.getDefaultInstance(properties);  
        emailSession.setDebug(true);

        //2) create the IMAP store object and connect with the Imap server  
        IMAPStore emailStore = (IMAPStore) emailSession.getStore(storeType);

        emailStore.connect(host, username, password);  

        //3) create the folder object and open it  
        Folder emailFolder = emailStore.getFolder("INBOX");  
        emailFolder.open(Folder.READ_ONLY);  

        //4) retrieve the messages from the folder in an array and print it  
        Message[] messages = emailFolder.getMessages();  
        for (int i = 0; i <messages.length; i++) 
        {
            Message message = messages[i];  
            MimeMessage m = new MimeMessage(emailSession);
            m.setContent(((MimeMessage)messages[i]).getContent() , "text/plain; charset=UTF-8");
            System.out.println("---------------------------------");  
            System.out.println("Email Number " + (i + 1));  
            System.out.println("Subject: " + message.getSubject());  
            System.out.println("From: " + message.getFrom()[0]);  
            System.out.println("Text: " + message.getContent().toString());  
            m.writeTo(System.out);
        }  

        //5) close the store and folder objects  
        emailFolder.close(false);  
        emailStore.close();  

    } 
    catch (NoSuchProviderException e) {e.printStackTrace();}   
    catch (MessagingException e) {e.printStackTrace();}  
    catch (IOException e) {e.printStackTrace();}

}

    public void stopThread()
    {
        this.done=true;
    }
}

我像这样从另一个类调用线程

connec=new Connection();
 (new Thread(connec)).start();

我收到以下错误：

javax.mail.MessagingException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target;
  nested exception is:
    javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:571)
    at javax.mail.Service.connect(Service.java:288)
    at javax.mail.Service.connect(Service.java:169)
    at mailpackage.Connection.check(Connection.java:63)
    at mailpackage.Connection.run(Connection.java:33)
    at java.lang.Thread.run(Thread.java:744)
Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1884)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:276)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:270)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1341)
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:153)
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:868)
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:804)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1016)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1312)
    at sun.security.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:882)
    at sun.security.ssl.AppInputStream.read(AppInputStream.java:102)
    at com.sun.mail.util.TraceInputStream.read(TraceInputStream.java:110)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:235)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:254)
    at com.sun.mail.iap.ResponseInputStream.readResponse(ResponseInputStream.java:98)
    at com.sun.mail.iap.Response.<init>(Response.java:96)
    at com.sun.mail.imap.protocol.IMAPResponse.<init>(IMAPResponse.java:61)
    at com.sun.mail.imap.protocol.IMAPResponse.readResponse(IMAPResponse.java:135)
    at com.sun.mail.imap.protocol.IMAPProtocol.readResponse(IMAPProtocol.java:261)
    at com.sun.mail.iap.Protocol.<init>(Protocol.java:114)
    at com.sun.mail.imap.protocol.IMAPProtocol.<init>(IMAPProtocol.java:104)
    at com.sun.mail.imap.IMAPStore.protocolConnect(IMAPStore.java:538)
    ... 5 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:385)
    at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
    at sun.security.validator.Validator.validate(Validator.java:260)
    at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:326)
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:126)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1323)
    ... 23 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:196)
    at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:268)
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
    ... 29 more

我读到一些关于 PKIX 路径错误的内容，说要将证书作为受信任的证书添加到 java 商店，但我不知道这是否是解决方案，如果是，我不知道该怎么做。

// 我无权访问邮件服务器

有什么建议么？谢谢！

Answer 1

好的问题解决了！

解决方案是这样的：

首先通过openssl从邮件服务器获取自签名证书：

echo | openssl s_client -connect yoursever:port 2>&1 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > yourcert.pem

然后将 yourcert.pem 文件保存到此路径 /Library/Java/Home/lib/security （在 macOSX 上）并将 cert 文件像这样放入 cacerts

keytool -keystore cacerts -importcert -alias youralias -file yourcert.pem

默认密钥库密码是 changeit

您可以查看使用显示证书指纹的此命令所做的更改。

keytool -list -keystore cacerts

在此之后，您应该在 VM 中传递这些参数

（对于 windows 和 linux，在 " " 之间键入 yourpath）

-Djavax.net.ssl.trustStore="/Library/Java/Home/lib/security/cacerts"

-Djavax.net.ssl.trustStorePassword="changeit"

对于调试：

-Djava.security.debug=certpath

-Djavax.net.debug=trustmanager

Answer 2

您可以尝试在https://java.net/projects/javamail/pages/Home升级库 javax.mail.jar （现在版本是 1.5.5）并添加代码：

MailSSLSocketFactory sf = new MailSSLSocketFactory();
sf.setTrustAllHosts(true); 
properties.put("mail.imap.ssl.trust", "*");
properties.put("mail.imap.ssl.socketFactory", sf);

Answer 3

这个 JavaMail FAQ 条目应该会有所帮助。

来自链接网站的引用文本：

问：通过 SSL 连接到我的邮件服务器时，我收到一个异常，例如“无法找到请求目标的有效证书路径”。

答：您的服务器可能正在使用测试证书或自签名证书，而不是由商业证书颁发机构签名的证书。您需要将服务器的证书安装到您的信任库中。InstallCert 程序会有所帮助。

或者，您可以将“mail.protocol.ssl.trust”属性设置为邮件服务器的主机名。有关详细信息，请参阅协议提供程序包的 javadocs。

此问题的其他常见原因是：

• 有防火墙或防病毒程序拦截了您的请求。
• 您的 JDK 安装出现问题，无法找到受信任的证书颁发机构的证书。
• 您在覆盖 JDK 的受信任证书颁发机构列表的应用程序服务器中运行。

Answer 4

通过从 Java 7 获取证书文件来解决此问题的简单方法

从以下 java 7 目录复制“cacerts”文件

C:\Program Files\Java\jdk1.7.0_79\jre\lib\security

并将其粘贴到 java 6 目录中

C:\Program Files\Java\jdk1.6.0\jre\lib\security

Answer 5

我已经失去了很多天来寻找解决方案，这篇文章对我有帮助。我有同样的问题。我像这里一样创建了一个 pem 文件，然后使用以下命令将证书文件 .pem 包含在 cacert 文件（名为 TrustStore.jks 的副本）中：

keytool.exe -import -noprompt -keystore TrustStore.jks -storepass changeit ^ -alias DOMAINNAME -file MYCERTFILE.pem

（DOMAINNAME 必须替换为主机名 - 这个技巧非常重要 - 并且 MYCERTFILE 由文件最近创建...）

我希望这个解决方案可以对某人有所帮助。

Answer 6

在与邮件服务器交谈时，我也遇到过这个问题。但是，根本原因是服务器（Exchange 2013）同时应用了真实证书和自签名证书。适当的做法是删除服务器上的自签名，因为它优先并阻止了真正的证书。