Module: Imobile::CryptoSupportAppFprint

Defined in:
lib/imobile/crypto_app_fprint.rb

Overview

Implementation details for crypto_app_fprint.

Class Method Summary collapse

Class Method Details

.app_fprint(device_or_hash, binary_path) ⇒ Object

An iPhone application’s finger-print, as implemented in CryptoSupport.



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# File 'lib/imobile/crypto_app_fprint.rb', line 106

def self.app_fprint(device_or_hash, binary_path)
  if device_or_hash.respond_to?(:[]) and device_or_hash.respond_to?(:keys)
    # Hash-like object.
    device_attributes = device_or_hash
  else
    # ActiveRecord model.
    device_attributes = device_or_hash.attributes
  end
  
  manifest_data = File.read binary_path
  app_fprint_from_raw_data device_attributes, manifest_data
end

.app_fprint_from_raw_data(device_attributes, manifest_data) ⇒ Object

An iPhone application’s finger-print, as implemented in CryptoSupport.

The device attributes should be passed in a Hash that represents the result of calling [ZNDeviceFprint deviceAttributes] on the iMobile device. The manifest data should be the result of reading the application’s manifest file (currently its executable file).

The returned finger-print is a hex-formatted string.



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# File 'lib/imobile/crypto_app_fprint.rb', line 99

def self.app_fprint_from_raw_data(device_attributes, manifest_data)
  key = device_fprint device_attributes
  iv = "\0" * 16
  data_fprint manifest_data, key, iv
end

.data_fprint(data_blob, key, iv = "\0" * 16) ⇒ Object

The finger-print for a data blob, as implemented in CryptoSupport.

Args:

data_blob:: a raw string, usually the result of reading a file
key:: 16-byte string, to be used as an AES key
iv:: 16-byte string, to be used as an AES key

The returned finger-print is a hex-formatted string.



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# File 'lib/imobile/crypto_app_fprint.rb', line 81

def self.data_fprint(data_blob, key, iv = "\0" * 16)
  cipher = OpenSSL::Cipher::Cipher.new 'aes-128-cbc'
  cipher.encrypt
  cipher.key, cipher.iv = key, iv
  
  plain = data_blob + "\0" * ((16 - (data_blob.length & 0x0f)) & 0x0f)
  crypted = cipher.update plain
  Digest::SHA2.hexdigest crypted
end

.device_fprint(device_attributes) ⇒ Object

The finger-print for a device’s attributes, as implemented in CryptoSupport.

The device attributes should be passed in a Hash that represents the result of calling [ZNDeviceFprint deviceAttributes] on the iMobile device.

The finger-print is returned as a raw string (no hex-formatting). In particular, the returned finger-print is suitable to be used as a key or IV for AES-128.

The code mirrors the reference code in ZergSupport’s test suite.



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# File 'lib/imobile/crypto_app_fprint.rb', line 45

def self.device_fprint(device_attributes)
  Digest::MD5.digest device_fprint_data(device_attributes)
end

.device_fprint_attributes ⇒ Object

The device attributes included in the finger-printing operation.



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# File 'lib/imobile/crypto_app_fprint.rb', line 68

def self.device_fprint_attributes
  Set.new(['app_id', 'app_version', 'app_provisioning', 'app_push_token',
           'hardware_model', 'os_name', 'os_version', 'unique_id'])
end

.device_fprint_data(device_attributes) ⇒ Object

The device data used for device finger-printing in CryptoSupport.

The device attributes should be passed in a Hash that represents the result of calling [ZNDeviceFprint deviceAttributes] on the iMobile device.



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# File 'lib/imobile/crypto_app_fprint.rb', line 61

def self.device_fprint_data(device_attributes)
  attrs = device_fprint_attributes
  keys = device_attributes.keys.select { |k| attrs.include? k.to_s }
  'D|' + keys.sort.map { |k| device_attributes[k] }.join('|')    
end

.hex_device_fprint(device_attributes) ⇒ Object

The finger-print for a device’s attributes, as implemented in CryptoSupport.

This method resembles device_fprint, but returns the finger-print in a hex-formatted string, so that it can be used by Web services.



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# File 'lib/imobile/crypto_app_fprint.rb', line 53

def self.hex_device_fprint(device_attributes)
  device_fprint(device_attributes).unpack('C*').map {|c| '%02x' % c}.join('')
end