Class: OpenPGP::Cipher

Inherits:
Object
  • Object
show all
Defined in:
lib/openpgp/cipher.rb,
lib/openpgp/cipher/aes.rb,
lib/openpgp/cipher/3des.rb,
lib/openpgp/cipher/idea.rb,
lib/openpgp/cipher/cast5.rb,
lib/openpgp/cipher/twofish.rb,
lib/openpgp/cipher/blowfish.rb

Overview

OpenPGP cipher algorithm.

Direct Known Subclasses

AES, Blowfish, CAST5, IDEA, TripleDES, Twofish

Defined Under Namespace

Classes: AES, AES128, AES192, AES256, Blowfish, CAST5, IDEA, TripleDES, Twofish

Constant Summary collapse

DEFAULT = 
AES128

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key, options = {}) ⇒ Cipher

Returns a new instance of Cipher.



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# File 'lib/openpgp/cipher.rb', line 38

def initialize(key, options = {})
  @key = case key
    when S2K then key.to_key(key_size)
    else S2K::Simple.new(key).to_key(key_size)
  end
  @options = options
end

Instance Attribute Details

#engine ⇒ Object

Returns the value of attribute engine.



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# File 'lib/openpgp/cipher.rb', line 36

def engine
  @engine
end

#key ⇒ Object

Returns the value of attribute key.



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# File 'lib/openpgp/cipher.rb', line 35

def key
  @key
end

#options ⇒ Object

Returns the value of attribute options.



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# File 'lib/openpgp/cipher.rb', line 35

def options
  @options
end

Class Method Details

.for(identifier) ⇒ Object

See Also:



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# File 'lib/openpgp/cipher.rb', line 20

def self.for(identifier)
  case identifier
    when Symbol then const_get(identifier.to_s.upcase)
    when String then const_get(identifier.upcase.to_sym)
    when 1      then IDEA
    when 2      then TripleDES
    when 3      then CAST5
    when 4      then Blowfish
    when 7      then AES128
    when 8      then AES192
    when 9      then AES256
    when 10     then Twofish
  end
end

.identifier ⇒ Object 



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# File 'lib/openpgp/cipher.rb', line 48

def self.identifier
  const_get(:IDENTIFIER)
end

.to_i ⇒ Object 



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# File 'lib/openpgp/cipher.rb', line 46

def self.to_i() identifier end

Instance Method Details

#block_size ⇒ Object 



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# File 'lib/openpgp/cipher.rb', line 60

def block_size
  @block_size ||= engine.block_size
end

#decrypt(ciphertext) ⇒ Object 



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# File 'lib/openpgp/cipher.rb', line 104

def decrypt(ciphertext)
  # TODO
  engine.reset
  engine.decrypt
end

#encrypt(plaintext) ⇒ Object

See Also:



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# File 'lib/openpgp/cipher.rb', line 72

def encrypt(plaintext)
  ciphertext = String.new

  engine.reset
  engine.encrypt

  # IV
  rblock = Random.bytes(block_size)
  iblock = encrypt_block("\0" * block_size)
  block_size.times do |i|
    ciphertext << (iblock[i] ^= rblock[i]).chr
  end

  # Checksum
  iblock = encrypt_block(iblock)
  ciphertext << (iblock[0] ^ rblock[block_size - 2]).chr
  ciphertext << (iblock[1] ^ rblock[block_size - 1]).chr

  # Resync
  iblock = ciphertext[2..-1]

  # Encrypt
  plaintext.size.times do |n|
    if (i = n % block_size) == 0
      iblock = encrypt_block(iblock)
    end
    ciphertext << (iblock[i] ^= plaintext[n]).chr
  end

  ciphertext
end

#encrypt_block(block) ⇒ Object 



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# File 'lib/openpgp/cipher.rb', line 110

def encrypt_block(block)
  engine.encrypt
  engine.key = @key
  engine.iv  = (@iv ||= "\0" * engine.iv_len)
  engine.update(block) << engine.final
end

#identifier ⇒ Object 



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# File 'lib/openpgp/cipher.rb', line 52

def identifier()
  self.class.identifier
end

#key_size ⇒ Object 



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# File 'lib/openpgp/cipher.rb', line 56

def key_size
  @key_size ||= engine.key_len
end