use native hkdf

[firien]

OpenSSL::KDF.hkdf has been around since ruby 2.5

require 'benchmark'
require 'openssl'
require 'hkdf'

salt = Random.new.bytes(16)
shared_secret = Random.new.bytes(32)
info = 'helloworld'

Benchmark.bm do |benchmark|
  n = 50_000
  benchmark.report('gem') do
    n.times do
      HKDF.new(shared_secret, salt: salt, algorithm: 'SHA256', info: info).next_bytes(32)
    end
  end
  benchmark.report('native') do
    n.times do
      OpenSSL::KDF.hkdf(shared_secret, salt: salt, info: info, hash: 'SHA256', length: 32)
    end
  end
end

[collimarco]

Thanks!

Here's my results:

       user     system      total        real
gem  2.643673   0.015704   2.659377 (  2.660243)
native  1.091457   0.001120   1.092577 (  1.092618)

Native is faster and we can also drop an external dependency.

All tests are passing.