Module: IrcBlowfish

Defined in:
lib/ircblowfish.rb,
lib/ircblowfish/base64.rb,
lib/ircblowfish/version.rb

Defined Under Namespace

Modules: Base64

Constant Summary collapse

VERSION = 
"0.1.1"

Class Method Summary collapse

Class Method Details

.decrypt(msg, key) ⇒ String

Decrypts a message using the specified key

Parameters:

  • msg (String) —

    the message to be decrypted

  • key (String) —

    the key used for decryption

Returns:

  • (String) —

    the decrypted message



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# File 'lib/ircblowfish.rb', line 22

def self.decrypt(msg, key)
  return decrypt_ecb(msg, key) if key =~ /^(?:old|ecb):/
  return decrypt_cbc(msg, key)
end

.decrypt_cbc(msg, key) ⇒ Object

Note:

Forces the use of Blowfish-CBC despite the key passed



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# File 'lib/ircblowfish.rb', line 114

def self.decrypt_cbc(msg, key)
  return msg if key.nil? or key == ''
  return msg if msg.nil? or msg == ''

  # Ensure the message is a valid Blowfish-CBC message and remove the prefix
  ciphertext = msg.dup
  return msg unless ciphertext.sub! %r{^\+(?:OK|mcps) \*}, ''

  # Remove the cbc: prefix if it's used
  key = key.sub %r{^cbc:}, ''
  return msg if key == ''

  # Decode the text to get the IV + ciphertext
  ciphertext = ::Base64.decode64 ciphertext

  return msg if ciphertext.bytesize < 8

  iv = ciphertext[0,8]           # Extract the IV from the string
  ciphertext = ciphertext[8..-1] # Remove the IV from the string

  return '' if ciphertext == ''

  # Create the Blowfish-CBC cipher
  cipher = OpenSSL::Cipher.new 'bf-cbc'
  cipher.decrypt
  cipher.key_len = key.length
  cipher.key = key
  cipher.padding = 0
  cipher.iv = iv

  # Decrypt the ciphertext and remove the trailing padding
  cipher.update(ciphertext).sub! %r{\x00*$}, ''
end

.decrypt_ecb(msg, key) ⇒ Object

Note:

Forces the use of Blowfish-ECB despite the key passed



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# File 'lib/ircblowfish.rb', line 56

def self.decrypt_ecb(msg, key)
  return msg if key.nil? or key == ''
  return msg if msg.nil? or msg == ''

  # Ensure the message is a valid Blowfish-ECB message and remove the prefix
  ciphertext = msg.dup
  return msg unless ciphertext.sub! %r{^\+(?:OK|mcps) }, ''
  return msg if ciphertext[0] == '*' # Dump if this is actually a Blowfish-CBC message
  return '' if ciphertext == '' # I've seen some clients send "+OK " for null messages

  # Remove the ecb:/old: prefix if it's used
  key = key.sub %r{^(?:old|ecb):}, ''
  return msg if key == ''

  # Create the Blowfish-CBC cipher
  cipher = OpenSSL::Cipher.new 'bf-ecb'
  cipher.decrypt
  cipher.key_len = key.length
  cipher.key = key
  cipher.padding = 0

  # Decrypt the ciphertext and remove the trailing padding
  cipher.update(IrcBlowfish::Base64.decode(ciphertext)).sub! %r{\x00*$}, ''
end

.encrypt(msg, key) ⇒ String

Encrypts a message using the specified key

Parameters:

  • msg (String) —

    the message to be encrypted

  • key (String) —

    the key used for encryption

Returns:

  • (String) —

    the encrypted message



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# File 'lib/ircblowfish.rb', line 13

def self.encrypt(msg, key)
  return encrypt_ecb(msg, key) if key =~ /^(?:old|ecb):/
  return encrypt_cbc(msg, key)
end

.encrypt_cbc(msg, key) ⇒ Object

Note:

Forces the use of Blowfish-CBC despite the key passed



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# File 'lib/ircblowfish.rb', line 83

def self.encrypt_cbc(msg, key)
  return msg if key.nil? or key == ''
  return msg if msg.nil? or msg == ''

  # Force encoding to binary in case of non-ascii messages
  plaintext = msg.dup.force_encoding 'BINARY'

  # Remove the cbc: prefix if it's used
  key = key.sub %r{^cbc:}, ''
  return msg if key == ''

  # Generate a random IV of length 8
  iv = random_iv 8

  # Create the Blowfish-CBC cipher
  cipher = OpenSSL::Cipher.new 'bf-cbc'
  cipher.encrypt
  cipher.key_len = key.length
  cipher.key = key
  cipher.padding = 0
  cipher.iv = iv

  # Add null padding to make the length a multiple of 8
  plaintext += "\x00" * (8 - (plaintext.bytesize % 8))

  # Generate the IRC message with prefix
  '+OK *' + ::Base64.encode64(iv + cipher.update(plaintext)).gsub!(/\n/, '')
end

.encrypt_ecb(msg, key) ⇒ Object

Note:

Forces the use of Blowfish-ECB despite the key passed



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# File 'lib/ircblowfish.rb', line 29

def self.encrypt_ecb(msg, key)
  return msg if key.nil? or key == ''
  return msg if msg.nil? or msg == ''

  # Force encoding to binary in case of non-ascii messages
  plaintext = msg.dup.force_encoding 'BINARY'

  # Remove the ecb:/old: prefix if it's used
  key = key.sub %r{^(?:old|ecb):}, ''
  return msg if key == ''

  # Create the Blowfish-CBC cipher
  cipher = OpenSSL::Cipher.new 'bf-ecb'
  cipher.encrypt
  cipher.key_len = key.length
  cipher.key = key
  cipher.padding = 0

  # Add null padding to make the length a multiple of 8
  plaintext += "\x00" * (8 - (plaintext.bytesize % 8))

  # Generate the IRC message with prefix
  '+OK ' + IrcBlowfish::Base64.encode(cipher.update(plaintext))
end