Module: Rmega::Crypto

Extended by:
Crypto
Included in:
Crypto
Defined in:
lib/rmega/crypto/aes.rb,
lib/rmega/crypto/rsa.rb,
lib/rmega/crypto/crypto.rb,
lib/rmega/crypto/aes_ctr.rb

Defined Under Namespace

Modules: Aes, AesCtr, Rsa

Instance Method Summary collapse

Instance Method Details

#decrypt_attributes(key, attributes_base64) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 58

def decrypt_attributes(key, attributes_base64)
  a32key = key.dup
  if a32key.size > 4
    a32key = [a32key[0] ^ a32key[4], a32key[1] ^ a32key[5], a32key[2] ^ a32key[6], a32key[3] ^ a32key[7]]
  end
  attributes = Crypto::Aes.decrypt a32key, Utils.base64_to_a32(attributes_base64)
  attributes = Utils.a32_to_str attributes
  JSON.parse attributes.gsub(/^MEGA/, '').rstrip
end

#decrypt_key(key, data) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 93

def decrypt_key(key, data)
  return Aes.decrypt(key, data) if data.size == 4
  x = []
  (0..data.size).step(4) do |i|
    cdata = [data[i] || 0, data[i+1] || 0, data[i+2] || 0, data[i+3] || 0]
    x.concat Crypto::Aes.decrypt(key, cdata)
  end
  x
end

#decrypt_sid(key, csid, privk) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 28

def decrypt_sid(key, csid, privk)
  # if csid ...
  t = Utils.mpi2b Utils.base64urldecode(csid)
  privk = Utils.a32_to_str decrypt_key(key, Utils.base64_to_a32(privk))
  rsa_privk = Array.new 4
  # else if tsid (todo)

  # Decompose private key
  4.times do |i|
    l = ((privk[0].ord * 256 + privk[1].ord + 7) >> 3) + 2
    rsa_privk[i] = Utils.mpi2b privk[0..l-1]
    privk = privk[l..-1]
  end

  # TODO - remove execjs and build the key using the ruby lib
  # rsa_key = Crypto::Rsa.build_rsa_key rsa_privk
  decrypted_t = Rsa.decrypt t, rsa_privk
  Utils.base64urlencode Utils.b2s(decrypted_t)[0..42]
end

#encrypt_attributes(key, attributes_hash) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 48

def encrypt_attributes(key, attributes_hash)
  a32key = key.dup
  if a32key.size > 4
    a32key = [a32key[0] ^ a32key[4], a32key[1] ^ a32key[5], a32key[2] ^ a32key[6], a32key[3] ^ a32key[7]]
  end
  attributes_str = "MEGA#{attributes_hash.to_json}"
  attributes_str << ("\x00" * (16 - (attributes_str.size % 16)))
  Crypto::Aes.encrypt a32key, Utils.str_to_a32(attributes_str)
end

#encrypt_key(key, data) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 82

def encrypt_key(key, data)
  return Aes.encrypt(key, data) if data.size == 4
  x = []
  (0..data.size).step(4) do |i|
    # cdata = [data[i] || 0, data[i+1] || 0, data[i+2] || 0, data[i+3] || 0]
    cdata = [data[i] || 0, data[i+1] || 0, data[i+2], data[i+3]].compact
    x.concat Crypto::Aes.encrypt(key, cdata)
  end
  x
end

#prepare_key(ary) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 14

def prepare_key(ary)
  pkey = [0x93C467E3,0x7DB0C7A4,0xD1BE3F81,0x0152CB56]
  65536.times do
    0.step(ary.size-1, 4) do |j|
      key = [0,0,0,0]
      4.times do |i|
        key[i] = ary[i+j] if i+j < ary.size
      end
      pkey = Aes.encrypt key, pkey
    end
  end
  pkey
end

#prepare_key_pw(password_str) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 68

def prepare_key_pw(password_str)
  prepare_key Utils.str_to_a32(password_str)
end

#random_key ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 10

def random_key
  Array.new(6).map { rand(0..0xFFFFFFFF) }
end

#stringhash(aes_key, string) ⇒ Object 



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# File 'lib/rmega/crypto/crypto.rb', line 72

def stringhash(aes_key, string)
  s32 = Utils::str_to_a32 string
  h32 = [0,0,0,0]

  s32.size.times { |i| h32[i & 3] ^= s32[i] }
  16384.times { h32 = Aes.encrypt aes_key, h32 }

  Utils::a32_to_base64 [h32[0],h32[2]]
end