module Capsium::Reactor::Htpasswd::Md5Crypt

md5-crypt as deployed by Apache htpasswd, OpenSSL and glibc ($1$ and $apr1$ magics; identical except for the magic string). NOTE: Poul-Henning Kamp’s original FreeBSD implementation mixed the magic in at the % 7 step where all deployed implementations mix in the password (see apr_md5.c, glibc crypt-md5.c).

Constants

DIGEST_GROUPS
ITOA64

Public Class Methods

digest (password, salt, magic)

(String password, String salt, String magic) → String

Source

# File lib/capsium/reactor/htpasswd.rb, line 35
def self.digest(password, salt, magic)
  final = initial_digest(password, salt, magic)
  1000.times do |i|
    final = stretch_digest(i, password, salt, final)
  end
  "#{magic}#{salt}$#{to64(final)}"
end

initial_digest (password, salt, magic)

(String password, String salt, String magic) → String

Source

# File lib/capsium/reactor/htpasswd.rb, line 43
def self.initial_digest(password, salt, magic)
  inner = Digest::MD5.digest(password + salt + password)
  context = Digest::MD5.new
  context << password << magic << salt
  length = password.length
  while length.positive?
    context << inner[0, [16, length].min]
    length -= 16
  end
  length = password.length
  while length.positive?
    context << (length.odd? ? "\0" : password[0])
    length >>= 1
  end
  context.digest
end

stretch_digest (iteration, password, salt, final)

(Integer iteration, String password, String salt, String final) → String

Source

# File lib/capsium/reactor/htpasswd.rb, line 60
def self.stretch_digest(iteration, password, salt, final)
  context = Digest::MD5.new
  context << (iteration.odd? ? password : final)
  context << salt unless (iteration % 3).zero?
  context << password unless (iteration % 7).zero?
  context << (iteration.odd? ? final : password)
  context.digest
end

to64 (final)

(String final) → String

Source

# File lib/capsium/reactor/htpasswd.rb, line 71
def self.to64(final)
  encoded = +""
  DIGEST_GROUPS.each do |a, b, c|
    value = final[c].ord | (final[b].ord << 8) | (final[a].ord << 16)
    4.times do
      encoded << ITOA64[value & 0x3f]
      value >>= 6
    end
  end
  value = final[11].ord
  2.times do
    encoded << ITOA64[value & 0x3f]
    value >>= 6
  end
  encoded
end

The custom base-64 of md5-crypt: digest triples permuted, first index to the high bits, 22 characters total.

verify (hash, password)

(String hash, String password) → bool

Source

# File lib/capsium/reactor/htpasswd.rb, line 28
def self.verify(hash, password)
  _prefix, magic, salt, = hash.split("$", 4)
  return false if salt.nil? || salt.empty?

  Reactor.secure_compare(digest(password, salt, "$#{magic}$"), hash)
end