Skip to content


Subversion checkout URL

You can clone with
Download ZIP
Rubygem for HMAC-based Key Derivation Function
Ruby Shell
branch: master
Failed to load latest commit information.
lib Clean up implementation
spec Cleanup test vector code
.gitignore Add bin to gitignore
.rvmrc Create the hkdf gem
.travis.yml Add ruby 2.2.0 to travis config
Gemfile Update version of rake
LICENSE Include LICENSE file Include LICENSE file
hkdf.gemspec Bump rspec and rake development dependencies

HKDF Build Status

This is a ruby implementation of RFC 5869: HMAC-based Extract-and-Expand Key Derivation Function. The goal of HKDF is to take some source key material and generate suitable cryptographic keys from it.


hkdf ='source key material')
 => "\f#\xF4b\x98\x9B\x7Fw>|/|k\xF4k\xB7\xB9\x11e\xC5\x92\xD1\fH\xFDG\x94vt\xB4\x14\xCE"

The default algorithm is HMAC-SHA256, you can override this and other defaults by providing an options hash during construction.

hkdf ='source key material', :salt => 'NaCl', :algorithm => 'SHA1', :info => 'the 411')
 => "\xC0<\x13\x85\x8C\x84z\xCE\xC7\xCE+\xFF\x1C\xEB\xE6\xBC"

You can also give an IO object as the source. It will be read in as a stream to generate the key. The optional argument :read_size can be used to control how many bytes are read from the IO at a time.

hkdf ='/tmp/filename'), :read_size => 512)
 => "\f#\xF4b\x98\x9B\x7Fw>|/|k\xF4k\xB7\xB9\x11e\xC5\x92\xD1\fH\xFDG\x94vt\xB4\x14\xCE"
Something went wrong with that request. Please try again.