解决128位秘钥长度限制的方法

RUN yum install -y unzip zip
RUN curl -q -L -C - -b "oraclelicense=accept-securebackup-cookie" -o /tmp/jce_policy-8.zip -O http://download.oracle.com/otn-pub/java/jce/8/jce_policy-8.zip \
&& unzip -oj -d  /opt/tuniu/jdk18/jre/lib/security /tmp/jce_policy-8.zip \*/\*.jar && rm /tmp/jce_policy-8.zip

public static void fixKeyLength() {
String errorString = "Failed manually overriding key-length permissions.";
int newMaxKeyLength;
try {
if ((newMaxKeyLength = Cipher.getMaxAllowedKeyLength("AES")) < 256) {
Class c = Class.forName("javax.crypto.CryptoAllPermissionCollection");
Constructor con = c.getDeclaredConstructor();
con.setAccessible(true);
Object allPermissionCollection = con.newInstance();
Field f = c.getDeclaredField("all_allowed");
f.setAccessible(true);
f.setBoolean(allPermissionCollection, true);

c = Class.forName("javax.crypto.CryptoPermissions");
con = c.getDeclaredConstructor();
con.setAccessible(true);
Object allPermissions = con.newInstance();
f = c.getDeclaredField("perms");
f.setAccessible(true);
((Map) f.get(allPermissions)).put("*", allPermissionCollection);

c = Class.forName("javax.crypto.JceSecurityManager");
f = c.getDeclaredField("defaultPolicy");
f.setAccessible(true);
Field mf = Field.class.getDeclaredField("modifiers");
mf.setAccessible(true);
mf.setInt(f, f.getModifiers() & ~Modifier.FINAL);
f.set(null, allPermissions);

newMaxKeyLength = Cipher.getMaxAllowedKeyLength("AES");
}
} catch (Exception e) {
throw new RuntimeException(errorString, e);
}
if (newMaxKeyLength < 256)
throw new RuntimeException(errorString); // hack failed
}