Module: Syndi::IRC::SASL::Mech::DHBlowfish

Defined in:
lib/syndi/irc/sasl/mech/dh_blowfish.rb

Overview

Module which implements the SASL DH-BLOWFISH mechanism.

Author:

  • noxgirl

Class Method Summary collapse

Class Method Details

.encrypt(username, password, provision) ⇒ Object

Create an SASL-encrypted hash.

Parameters:

  • username (String) —

    The username.

  • password (String) —

    The password associated with the username.

  • provision (String) —

    The key provided by the server.



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# File 'lib/syndi/irc/sasl/mech/dh_blowfish.rb', line 26

def self.encrypt username, password, provision
  # This is a fairly complex process. Duplicate +username+ and
  # +password+ for safety.
  user = username.dup
  pass = password.dup

  # Decode the key from base64.
  key = Base64.decode64(provision).force_encoding('ASCII-8BIT')

  # Unpack it.
  p, g, y = unpack_key key

  dh     = DiffieHellman.new(p, g, 23)
  pkey   = dh.generate
  secret = OpenSSL::BN.new(dh.secret(y).to_s).to_s(2)
  pub    = OpenSSL::BN.new(pkey.to_s).to_s(2)

  pass.concat "\0"
  pass.concat('.' * (8 - (password.size % 8)))

  cipher         = OpenSSL::Cipher::Cipher.new 'BF-ECB'
  cipher.key_len = 32
  cipher.encrypt
  cipher.key     = secret

  enc    = cipher.update(pass).to_s
  answer = [pub.bytesize, pub, user, enc].pack('na*Z*a*')

  Base64.strict_encode64(answer) # finally, return the hash
end

.unpack_key(key) ⇒ Array(Numeric, Numeric, Numeric)

Returns +p+, +g+, and +y+ for Diffie-Hellman key exchange.

Returns:

  • (Array(Numeric, Numeric, Numeric)) —

    +p+, +g+, and +y+ for Diffie-Hellman key exchange



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# File 'lib/syndi/irc/sasl/mech/dh_blowfish.rb', line 59

def self.unpack_key key
  key = key.dup
  pgy = []

  3.times do
    size = key.unpack('n').first
    key.slice! 0, 2
    pgy << key.unpack("a#{size}").first
    key.slice!(0, size)
  end
  
  pgy.map { |int| OpenSSL::BN.new(int, 2).to_i }
end