Faster RSA Ciphers on JRuby

23 July 2015

When most people think about Lookout, they rarely consider more software than what is available in the Android or iOS App Stores. But truth be told, the vast majority of what powers Lookout, and in fact makes us Lookout, is a very large set of backend web and data services offloading a tremendous amount of work from mobile clients themselves. The platform powering a non-trivial amount of this backend infrastructure is JRuby.

The JRuby runtime is compelling for a number of reasons, one of the most often touted is performance. Like many users we’ve generally seen good performance from JRuby, so imagine our surprise when we found ponderously slow performance in some of our OpenSSL operations.

Despite generally positive Ruby performance in JRuby, overall performance is still tied to the capabilities of the JVM itself. In the case of OpenSSL operations, what’s really being compared is the performance of Java’s SSL library versus the openssl’s C library. Unfortunately, for RSA-specific operations, Java has some slower math operations under the covers. For example, here’s some benchmark code using RSA ciphers for signing/signature verification/encryption/decription on MRI versus JRuby 1.7.21:

$ ruby2.1 -v benchmark.rb
ruby 2.1.2p95 (2014-05-08) [x86_64-linux-gnu]
                        user     system      total        real
sign                9.710000   0.000000   9.710000 (  9.706266)
verify              0.150000   0.000000   0.150000 (  0.158150)
encrypt             0.170000   0.000000   0.170000 (  0.167504)
decrypt             9.720000   0.000000   9.720000 (  9.716763)

$ ruby -I benchmark.rb
jruby 1.7.21 (1.9.3p551) 2015-07-07 a741a82 on OpenJDK 64-Bit Server VM
1.7.0_79-b14 +jit [linux-amd64]

                        user     system      total        real
sign               45.600000   0.230000  45.830000 ( 45.451000)
verify              0.950000   0.000000   0.950000 (  0.810000)
encrypt             0.790000   0.060000   0.850000 (  0.815000)
decrypt            45.280000   0.080000  45.360000 ( 45.257000)

Signing and decryption operations in JRuby are 5x slower than their counter-parts in MRI!

Fortunately, this is a known problem and our colleagues at Square have published jnagmp and bouncycastle-rsa which provides some faster math calls to the JVM, significantly improving the performance of RSA operations on the JVM.

Today we’re releasing a small gem called fast-rsa-engine which we’ve written to incorporate Square’s “bouncycastle-rsa” into the jruby-openssl library.

Revisiting that same benchmark from above with fast-rsa-engine loaded into the JRuby runtime:

$ ruby -v benchmark.rb
jruby 1.7.21 (1.9.3p551) 2015-07-07 a741a82 on OpenJDK 64-Bit Server VM
1.7.0_79-b14 +jit [linux-amd64]
                        user     system      total        real
sign               11.160000   0.000000  11.160000 ( 11.055000)
verify              0.450000   0.010000   0.460000 (  0.324000)
encrypt             0.420000   0.050000   0.470000 (  0.343000)
decrypt            11.050000   0.080000  11.130000 ( 10.972000)

Instead of 5x slower, it’s now only 1.2x slower, which is a big speed up!

These improvements exist as a stand-alone gem currently, and may in the future be incorporated into jruby-openssl. For now however, you can install the gem from with gem install fast-rsa-engine

If you’re interested in talking about JRuby, OpenSSL or fun on the JVM, come talk to us at JRubyConf EU 2015!