Ben Poweski's Weblog

For the most part Ruby has fantastic APIs. While there is an occasional wart here and there (I”m speaking to you DateTime). In general, it doesn’t suck. The OpenSSL bindings for Ruby are no exception.

Bob, meet Alice

To begin our cultural learnings of OpenSSL and Ruby, let’s take a look at source repository for the interpreter. In the samples directory are some nice examples how the bindings work. It seems that some of the original code examples were never migrated from the RubyPKI project, but thats ok, you can still access them here.

The OpenSSL Digest Class

One of the most common things you’ll most likely need is to create a digest of a string of data. We can do this using by instantiating a Digest class then invoking the hexdigest method.

irb(main):001:0> require 'openssl'
=> true
irb(main):002:0> @sha1 = OpenSSL::Digest::SHA1.new("fooooo")
=> 58c00efa9bed725721b29f4b5f7864f0f191cad5
irb(main):003:0> @sha1.hexdigest
=> "58c00efa9bed725721b29f4b5f7864f0f191cad5"
irb(main):005:0>

Simple enough. But what is the deal with ‘digest’ versus ‘openssl/digest’? According to the ‘digest’ module is only used for backwards compatibility, so use the openssl version when possible.

Available Digest Algorithms

According to the source, the Digest algorithms available are dependent upon the version of OpenSSL compiled with Ruby.

module OpenSSL
  class Digest

    alg = %w(DSS DSS1 MD2 MD4 MD5 MDC2 RIPEMD160 SHA SHA1)
    if OPENSSL_VERSION_NUMBER > 0x00908000
      alg += %w(SHA224 SHA256 SHA384 SHA512)
    end
    ...