Class: Decrypt

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

Class Method Summary collapse

Class Method Details

.aes_decrypt(data, key, iv) ⇒ Object 



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# File 'lib/decrypt.rb', line 11

def self.aes_decrypt(data, key, iv)
  decipher = OpenSSL::Cipher::AES.new(128, :CBC)
  decipher.decrypt
  decipher.key = key
  decipher.iv = iv
  begin
    plain = decipher.update(data)
    plain << decipher.final
  rescue OpenSSL::Cipher::CipherError
    nil
  end
end

.base64_decode(base64_encoded_string) ⇒ Object 



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# File 'lib/decrypt.rb', line 4

def self.base64_decode(base64_encoded_string)
  decoded_data = base64_encoded_string.unpack('m')[0]
  salt = decoded_data[8..15]
  data = decoded_data[16..decoded_data.length-1]
  {salt: salt, data: data}
end

.decrypt_pbkdf2(master_password, data, iterations) ⇒ Object 



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# File 'lib/decrypt.rb', line 42

def self.decrypt_pbkdf2(master_password, data, iterations)
  encrypted = base64_decode(data)
  key_and_iv = derive_pbkdf2(master_password, encrypted[:salt], iterations)
  aes_decrypt(encrypted[:data], key_and_iv[:key], key_and_iv[:iv])
end

.decrypt_ssl(master_key, validation) ⇒ Object 



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# File 'lib/decrypt.rb', line 48

def self.decrypt_ssl(master_key, validation)
  encrypted = base64_decode(validation)
  key_and_iv = derive_openssl(master_key, encrypted[:salt])
  aes_decrypt(encrypted[:data], key_and_iv[:key], key_and_iv[:iv])
end

.derive_openssl(key, content_salt) ⇒ Object 



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

def self.derive_openssl(key, content_salt)
  key = key[0,1024]
  key_and_iv = ""
  prev = ""

  while key_and_iv.length < 32 do
      prev = Digest::MD5.digest(prev + key + content_salt)
      key_and_iv << prev
  end

  {key: key_and_iv[0,16], iv: key_and_iv[16..-1]}
end

.derive_pbkdf2(password, salt, iterations) ⇒ Object 



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# File 'lib/decrypt.rb', line 24

def self.derive_pbkdf2(password, salt, iterations)
  key_and_iv = OpenSSL::PKCS5.pbkdf2_hmac_sha1(password, salt, iterations, 32)
  {key: key_and_iv[0,16], iv: key_and_iv[16..-1]}
end