Class: Hydan::Crypto::DecryptionHelper

Inherits:
Object
  • Object
show all
Defined in:
lib/hydan/crypto/decrypt.rb

Instance Method Summary collapse

Constructor Details

#initialize(symmetric_key) ⇒ DecryptionHelper

Returns a new instance of DecryptionHelper.



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# File 'lib/hydan/crypto/decrypt.rb', line 5

def initialize(symmetric_key)
  @master_key = symmetric_key
  @generator = OpenSSL::Cipher.new(Crypto::DEFAULT_CIPHER)
end

Instance Method Details

#decrypt(json) ⇒ String

Decrypts a JSON object

Returns:

  • (String) 


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# File 'lib/hydan/crypto/decrypt.rb', line 12

def decrypt(json)
  input_hash = JSON.parse(json)
  data_key = Base64.strict_decode64(input_hash['data_key'])
  key_cipher = Gibberish::AES.new(@master_key)
  plaintext_key = key_cipher.decrypt(data_key)
  data_cipher = Gibberish::AES.new(plaintext_key)
  plaintext = data_cipher.decrypt(JSON.generate(input_hash['ciphertext']))
  plaintext
end

#decrypt_env_file(env_body) ⇒ Object

# Decrypts an env-formatted text string. # A file is considered to be env-formatted when: # - Each line consists of K=V pairs # - Each V is a JSON string that contains a Gibberish # payload (ciphertext, IV, salt, etc) and an encrypted # data key that was used to encrypt the ciphertext # @return [String]



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# File 'lib/hydan/crypto/decrypt.rb', line 40

def decrypt_env_file(env_body)
  new_text = []
  env_body.each_line do |l|
    k, v = l.match(Hydan::IO::ENV_LINE_REGEX).captures
    dec_v = decrypt(v)
    new_text << "#{k}=#{dec_v}"
  end
  new_text
end

#decrypt_file(in_file, out_file, key) ⇒ Object

Decrypts a file



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# File 'lib/hydan/crypto/decrypt.rb', line 23

def decrypt_file(in_file, out_file, key)
  key_cipher = Gibberish::AES::CBC.new(@master_key)
  # The return value for this is Base64-encoded by default,
  # we're overriding it here to later #strict_encode64 it.
  data_key = key_cipher.decrypt(key, binary: true)
  data_cipher = Gibberish::AES::CBC.new(data_key)
  data_key = nil # Scrub from memory as soon as feasible
  data_cipher.decrypt_file(in_file, out_file)
end