报错 Illegal key size

报错 Illegal key size

Java 环境

java version "1.8.0_151"
Java(TM) SE Runtime Environment (build 1.8.0_151-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.151-b12, mixed mode)

解决办法

在前面我们没有提及一个东西，就是在/usr/local/java/jdk1.8.0_151/jre/lib/security/policy/下有两个目录。

[root@djx-117106 policy]# pwd
/usr/local/java/jdk1.8.0_151/jre/lib/security/policy/
[root@djx-117106 policy]# ls -l
total 8
drwxr-xr-x 2 root root 4096 Nov  2 10:47 limited
drwxr-xr-x 2 root root 4096 Nov  2 10:47 unlimited
[root@djx-117106 policy]# ls -l ./limited/
total 8
-rw-r--r-- 1 root root 3405 Jul  4 19:41 local_policy.jar
-rw-r--r-- 1 root root 2920 Jul  4 19:41 US_export_policy.jar
[root@djx-117106 policy]# ls -l ./unlimited/
total 8
-rw-r--r-- 1 root root 2929 Jul  4 19:41 local_policy.jar
-rw-r--r-- 1 root root 2917 Jul  4 19:41 US_export_policy.jar

有一个 limited 目录(也就是对解密有限制的包，只支持 128位)，也有一个 ulimited 目录(也就是没有限制的目录)。

更改 源码

我们在 /usr/local/java/jdk1.8.0_151/jre/lib/security/ 下的 java.security文件中看到。

# To support older JDK Update releases, the crypto.policy property
# is not defined by default. When the property is not defined, an
# update release binary aware of the new property will use the following
# logic to decide what crypto policy files get used :
#
# * If the US_export_policy.jar and local_policy.jar files are located
# in the (legacy) <java-home>/lib/security directory, then the rules
# embedded in those jar files will be used. This helps preserve compatibility
# for users upgrading from an older installation.
#
# * If crypto.policy is not defined and no such jar files are present in
# the legacy locations, then the JDK will use the limited settings
# (equivalent to crypto.policy=limited)
#
# Please see the JCA documentation for additional information on these
# files and formats.
#crypto.policy=unlimited

注意下文中的 (equivalent to crypto.policy=limited) 说明默认是使用的 limited.
我们只需要加 crypto.policy=unlimited. 让默认使用的不限制的。

替换Jar包

替换 /usr/local/java/jdk1.8.0_151/jre/lib/security/policy/limited的路径的包。其实我们可以直接用 /usr/local/java/jdk1.8.0_151/jre/lib/security/policy/unlimited下面的包直接替换 /usr/local/java/jdk1.8.0_151/jre/lib/security/policy/limited/ 下面的两个包。也就是让默认使用不限制的jar包。

升级 Java 版本

Java™ SE Development Kit 8, Update 161
在官方文档写到，

security-libs/javax.crypto
 Unlimited cryptography enabled by default
The JDK uses the Java Cryptography Extension (JCE) Jurisdiction Policy files to configure cryptographic algorithm restrictions. Previously, the Policy files in the JDK placed limits on various algorithms. This release ships with both the limited and unlimited jurisdiction policy files, with unlimited being the default. The behavior can be controlled via the new 'crypto.policy' Security property found in the /lib/java.security file. Please refer to that file for more information on this property.

也就是从 1.8.0_161-b12 版本后，默认将采用无限制的加密算法，也就是使用 unlimited 下的jar包。我们也可以通过 设置 java.security 文件的 crypto.policy的值来改变这个默认的值。