getrandom() Provider

A secure random provider that uses Linux kernel functions.

License	MIT
Categories	IDE Development Tools
GroupId	com.github.marschall
ArtifactId	getrandom-provider
Last Version	0.1.1
Release Date	Jan 21, 2018
Type	jar
Description	getrandom() Provider A secure random provider that uses Linux kernel functions.

Download getrandom-provider

Filename	Size
getrandom-provider-0.1.1.pom
getrandom-provider-0.1.1.jar	12 KB
getrandom-provider-0.1.1-sources.jar	8 KB
getrandom-provider-0.1.1-javadoc.jar	380 KB

How to add to project

Apache Maven

<!-- https://jarcasting.com/artifacts/com.github.marschall/getrandom-provider/ -->
<dependency>
    <groupId>com.github.marschall</groupId>
    <artifactId>getrandom-provider</artifactId>
    <version>0.1.1</version>
</dependency>

Gradle Groovy

// https://jarcasting.com/artifacts/com.github.marschall/getrandom-provider/
implementation 'com.github.marschall:getrandom-provider:0.1.1'

Gradle Kotlin

// https://jarcasting.com/artifacts/com.github.marschall/getrandom-provider/
implementation ("com.github.marschall:getrandom-provider:0.1.1")

Apache Buildr

'com.github.marschall:getrandom-provider:jar:0.1.1'

Apache Ivy

<dependency org="com.github.marschall" name="getrandom-provider" rev="0.1.1">
  <artifact name="getrandom-provider" type="jar" />
</dependency>

Groovy Grape

@Grapes(
@Grab(group='com.github.marschall', module='getrandom-provider', version='0.1.1')
)

Scala SBT

libraryDependencies += "com.github.marschall" % "getrandom-provider" % "0.1.1"

Leiningen

[com.github.marschall/getrandom-provider "0.1.1"]

Dependencies

test (4)

Group / Artifact	Type	Version
org.junit.jupiter : junit-jupiter-api	jar	5.0.2
org.junit.jupiter : junit-jupiter-engine	jar	5.0.2
org.junit.platform : junit-platform-launcher	jar	1.0.2
org.hamcrest : hamcrest-junit	jar	2.0.0.0

Project Modules

There are no modules declared in this project.

getrandom() SecureRandomSPI

A SecureRandomSPI that makes getrandom() system call available to SecureRandom.

• uses syscall, does not depend on glibc wrapper
• tries to use stack allocation rather than allocation on the C heap
• is marked as thread safe so concurrent access through SecureRandom will not synchronize in Java 9 and later, however there seems to be a kernel lock on /dev/urandom so you will likely not get additional parallelism
• unlike the NativePRNG variants
  • does not use a file handle
  • does not have a global lock, but see comments on the kernel lock above
  • does not additionally mix with SHA1PRNG
  • blocks until the urandom source has been initialized
  • zeros out native memory
• supports the ServiceLoader mechanism
• is a Java 9 module but works on Java 8
• no dependencies outside the java.base module

Usage

A nonblocking (/dev/urandom) instance of the provider can be acquired using

SecureRandom.getInstance("geturandom"); // GetrandomProvider.GETURANDOM

Alternatively a blocking (/dev/random) instance of the provider can be acquired using

SecureRandom.getInstance("getrandom"); // GetrandomProvider.GETRANDOM

The /dev/urandom variant is the preferred one, the /dev/random variant is only added for completeness, see Myths about /dev/urandom.

Configuration

The provider can be configured in two different ways

1. programmatic configuration
2. static configuration

For best startup performance it is recommended to extract the .so from the JAR and add it to a folder present in the LD_LIBRARY_PATH environment variable or the java.library.path system property. Otherwise this library will extract the .so to a temporary folder the first time it is called.

Programmatic Configuration

The provider can be registered programmatically using

Security.addProvider(new GetrandomProvider());

Static Configuration Java 8

The provider can be configured statically in the java.security file by adding the provider at the end

security.provider.N=com.github.marschall.getrandom.GetrandomProvider

N should be the value of the last provider incremented by 1. For Oracle/OpenJDK 8 on Linux N should likely be 10.

This can be done per JVM installation or per JVM Instance.

Note that for this to work the provider JAR needs to be in the class path or extension folder.

Static Configuration Java 9+

The provider can be configured statically in the java.security file by adding the provider at the end

security.provider.N=getrandom

N should be the value of the last provider incremented by 1. For Oracle/OpenJDK 9 on Linux N should likely be 13.

This can be done per JVM installation or per JVM Instance.

The provider uses the ServiceLoader mechanism therefore using the getrandom string is enough, there is no need to use the fully qualified class name.

Note that for this to work the provider JAR needs to be in the class path or module path.

Performance

Performance compared to NativePRNGNonBlocking is lower for small, single threaded workloads due to the syscall overhead and additionally negatively impacted by the meltdown patches. However for large or threaded workloads performance is higher.

Usage for Tomcat Session Ids

This security provider can be used for session id generation in Tomcat. In order for that several things need to be configured:

1. the JAR needs to be added to the class path
2. the .so should be added to the Java library path (java.library.path)
3. the provider needs to be installed into the JVM via java.security.properties
4. Tomcat needs to be configured to use the algorithm

Points 1, 2 and 3 can be configured in CATALINA_BASE/bin/setenv.sh

#!/bin/sh

CLASSPATH="/path/to/getrandom-provider-0.1.1.jar"
CATALINA_OPTS="$CATALINA_OPTS -Djava.library.path=/path/to/folder/with/so -Djava.security.properties=/path/to/jvm.java.security"

export CLASSPATH
export CATALINA_OPTS

Point can be configured on the Manager Component in conf/context.xml by setting secureRandomAlgorithm to geturandom

<Manager secureRandomAlgorithm="geturandom">
</Manager>

Versions

Version
0.1.1 Jan 21, 2018
0.1.0 Jan 7, 2018