class Eth::Key::Decrypter

The {Eth::Key::Decrypter} class to handle PBKDF2-SHA-256 decryption.

def self.perform(data, password)

Returns:
  • (Eth::Key) - decrypted key-pair.

Parameters:
  • password (String) -- password to decrypt the key.
  • data (JSON) -- encryption data including cypherkey. 
def self.perform(data, password)
  new(data, password).perform
end

def check_macs 

def check_macs
  mac1 = Util.keccak256(key[(key_length / 2), key_length] + ciphertext)
  mac2 = Util.hex_to_bin crypto_data["mac"]
  if mac1 != mac2
    raise DecrypterError, "Message Authentications Codes do not match!"
  end
end

def cipher 

def cipher
  @cipher ||= OpenSSL::Cipher.new(cipher_name).tap do |cipher|
    cipher.decrypt
    cipher.key = key[0, (key_length / 2)]
    cipher.iv = iv
  end
end

def cipher_name 

def cipher_name
  "aes-128-ctr"
end

def ciphertext 

def ciphertext
  Util.hex_to_bin crypto_data["ciphertext"]
end

def crypto_data 

def crypto_data
  @crypto_data ||= data["crypto"] || data["Crypto"]
end

def decrypted_data 

def decrypted_data
  @decrypted_data ||= cipher.update(ciphertext) + cipher.final
end

def derive_key(password) 

def derive_key(password)
  case kdf
  when "pbkdf2"
    @key = OpenSSL::PKCS5.pbkdf2_hmac(password, salt, iterations, key_length, digest)
  when "scrypt"
    @key = SCrypt::Engine.scrypt(password, salt, n, r, p, key_length)
  else
    raise DecrypterError, "Unsupported key derivation function: #{kdf}!"
  end
end

def digest 

def digest
  OpenSSL::Digest.new digest_name
end

def digest_name 

def digest_name
  "sha256"
end

def initialize(data, password)

Parameters:
  • password (String) -- password to decrypt the key.
  • data (JSON) -- encryption data including cypherkey. 
def initialize(data, password)
  data = JSON.parse(data) if data.is_a? String
  @data = data
  @password = password
end

def iterations 

def iterations
  crypto_data["kdfparams"]["c"].to_i
end

def iv 

def iv
  Util.hex_to_bin crypto_data["cipherparams"]["iv"]
end

def kdf 

def kdf
  crypto_data["kdf"]
end

def key_length 

def key_length
  crypto_data["kdfparams"]["dklen"].to_i
end

def n 

def n
  crypto_data["kdfparams"]["n"].to_i
end

def p 

def p
  crypto_data["kdfparams"]["p"].to_i
end

def perform

Returns:
  • (Eth::Key) - decrypted key. 
def perform
  derive_key password
  check_macs
  private_key = Util.bin_to_hex decrypted_data
  Eth::Key.new priv: private_key
end

def r 

def r
  crypto_data["kdfparams"]["r"].to_i
end

def salt 

def salt
  Util.hex_to_bin crypto_data["kdfparams"]["salt"]
end