Class: ChaCha20

Inherits:
Object
  • Object
show all
Defined in:
lib/chacha20/chacha20.rb,
ext/chacha20/chacha20_bindings.c

Instance Method Summary collapse

Constructor Details

#initialize(key, nonce = nil) ⇒ ChaCha20

Returns a new instance of ChaCha20.

Raises:

  • (TypeError) 


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# File 'lib/chacha20/chacha20.rb', line 2

def initialize(key, nonce = nil)
  if nonce.nil?
    @nonce_initialized = false
    nonce = "\x00".b * 8
  else
    @nonce_initialized = true
  end

  raise TypeError, "key must be a String" unless key.is_a? String
  raise TypeError, "nonce must be a String" unless nonce.is_a? String

  raise ArgumentError, "key must be 32 bytes" unless key.bytesize == 32
  raise ArgumentError, "nonce must be 8 bytes" unless nonce.bytesize == 8

  @block_offset = 0

  init_context(key, nonce)
end

Instance Method Details

#encrypt(input) ⇒ Object Also known as: decrypt

Raises:

  • (ArgumentError) 


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# File 'lib/chacha20/chacha20.rb', line 47

def encrypt(input)
  raise "nonce has not been initialized" unless @nonce_initialized
  raise ArgumentError, "plaintext must be a string" unless input.is_a?(String)

  length = input.bytesize

  result = "\x00".b * @block_offset + input
  result = encrypt_or_decrypt(result)
  result = result.slice(@block_offset, length)

  @block_offset = (@block_offset + length) % 64
  set_counter(get_counter - 1) unless @block_offset.zero?

  result
end

#init_nonce(nonce) ⇒ Object

Raises:

  • (TypeError) 


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# File 'lib/chacha20/chacha20.rb', line 21

def init_nonce(nonce)
  raise "nonce has already been initialized" if @nonce_initialized
  raise TypeError, "nonce must be a String" unless nonce.is_a? String
  raise ArgumentError, "nonce must be 8 bytes" unless nonce.bytesize == 8

  @nonce_initialized = true
  set_nonce(nonce)
end

#initialized? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chacha20/chacha20.rb', line 35

def initialized?
  @nonce_initialized
end

#nonce ⇒ Object 



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# File 'lib/chacha20/chacha20.rb', line 30

def nonce
  raise "nonce has not been initialized" unless @nonce_initialized
  get_nonce
end

#seek(position) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/chacha20/chacha20.rb', line 39

def seek(position)
  raise "nonce has not been initialized" unless @nonce_initialized
  raise ArgumentError, "position must be a non-negative integer" unless position.is_a?(Integer) && position >= 0

  set_counter(position / 64)
  @block_offset = position % 64
end