问题背景

java项目中引用了sshj依赖包远程执行ssh命令，执行ssh的命令在环境上可以正常运行，但通过单元测试验证ssh命令时提示如下错误：

2024-03-28 17:25:22 WARN  DefaultConfig:206 - Disabling high-strength ciphers: cipher strengths apparently limited by JCE policy
2024-03-28 17:25:22 INFO  TransportImpl:214 - Client identity string: SSH-2.0-SSHJ_0.27.0
2024-03-28 17:25:22 INFO  TransportImpl:178 - Server identity string: SSH-2.0-OpenSSH_7.4
2024-03-28 17:25:23 ERROR TransportImpl:593 - Dying because - Invalid signature file digest for Manifest main attributes
java.lang.SecurityException: Invalid signature file digest for Manifest main attributes
    at sun.security.util.SignatureFileVerifier.processImpl(SignatureFileVerifier.java:317)
    at sun.security.util.SignatureFileVerifier.process(SignatureFileVerifier.java:259)
    at java.util.jar.JarVerifier.processEntry(JarVerifier.java:323)
    at java.util.jar.JarVerifier.update(JarVerifier.java:234)
    at java.util.jar.JarFile.initializeVerifier(JarFile.java:394)
    at java.util.jar.JarFile.ensureInitialization(JarFile.java:632)
    at java.util.jar.JavaUtilJarAccessImpl.ensureInitialization(JavaUtilJarAccessImpl.java:69)
    at sun.misc.URLClassPath$JarLoader$2.getManifest(URLClassPath.java:993)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:456)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:74)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:369)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:363)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:362)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
    at net.schmizz.sshj.common.KeyType$3.isMyType(KeyType.java:124)
    at net.schmizz.sshj.common.KeyType.fromKey(KeyType.java:288)
    at net.schmizz.sshj.transport.kex.AbstractDHG.next(AbstractDHG.java:82)
    at net.schmizz.sshj.transport.KeyExchanger.handle(KeyExchanger.java:364)
    at net.schmizz.sshj.transport.TransportImpl.handle(TransportImpl.java:503)
    at net.schmizz.sshj.transport.Decoder.decodeMte(Decoder.java:159)
    at net.schmizz.sshj.transport.Decoder.decode(Decoder.java:79)
    at net.schmizz.sshj.transport.Decoder.received(Decoder.java:231)
    at net.schmizz.sshj.transport.Reader.run(Reader.java:59)
2024-03-28 17:25:23 INFO  TransportImpl:192 - Disconnected - UNKNOWN
2024-03-28 17:25:23 ERROR Promise:174 - <<kex done>> woke to: net.schmizz.sshj.transport.TransportException: Invalid signature file digest for Manifest main attributes
2024-03-28 17:25:23 ERROR:573 - failed exec command ls /root/ on node 10.10.2.8

根据报错信息Invalid signature file digest for Manifest main attributes，查找相关资料，尝试以下几种解决方法都没有效果：

1. 自定义provider：Security.addProvider(new sun.security.ec.SunEC());
2. 禁用JCE加密限制：Security.setProperty("crypto.policy", "unlimited");
3. 基于sshj的SecurityUtils设置provider：

将BC提供者设置为SSHJ的安全提供者
SecurityUtils.setSecurityProvider(String.valueOf(Security.getProvider("BC")));

将JCE提供者设置为SSHJ的安全提供者
SecurityUtils.setSecurityProvider(String.valueOf(Security.getProvider("SunJCE")));

查sshj相关issue[1]，发现一个类似的问题，原因是bcprov的签名无法被验证。查看bcprov的签名情况：

有问题的版本：
[root@node1 1.0.0]# /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64/bin/jarsigner -verify bcprov-jdk15on-1.60.jar
jarsigner: java.lang.SecurityException: Invalid signature file digest for Manifest main attributes

高版本：
[root@node1 1.0.0]# /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64/bin/jarsigner -verify bcprov-jdk15on-1.69.jar
jar 已验证。
警告:
此 jar 包含其证书链无效的条目。原因: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
The DSA signing key has a keysize of 1024 which is considered a security risk. This key size will be disabled in a future update.

看起来是版本问题，更新项目中的bcprov版本到1.69，重新测试后报错消失，显示正常的命令执行结果：

2024-03-29 09:00:08 INFO  BouncyCastleRandom:48 - Generating random seed from SecureRandom.
2024-03-29 09:00:08 INFO  TransportImpl:214 - Client identity string: SSH-2.0-SSHJ_0.27.0
2024-03-29 09:00:08 INFO  TransportImpl:178 - Server identity string: SSH-2.0-OpenSSH_7.4
2024-03-29 09:00:08 INFO  TransportImpl:192 - Disconnected - BY_APPLICATION
anaconda-ks.cfg

解决方案

升级依赖包bcprov的版本到1.69。

参考资料

1. https://github.com/hierynomus/sshj/issues/701