function _Load_Decryption_Cipher($validate_key = true)
{
// If legacy, switch to legacy mode
if ($this->job['legacy']) {
return $this->_Legacy_Load_Decryption_Cipher($validate_key);
}
// Attempt to open the cipher module
if ($this->job['header']['version'] >= 3) {
list($module, $module_str, $key_size) = $this->_Get_Cipher($this->progress['config']['enc_type']);
} else {
list($module, $module_str, $key_size) = $this->_Get_Cipher_NonStandard($this->progress['config']['enc_type']);
}
if (false === ($this->cipher = @mcrypt_module_open($module, '', MCRYPT_MODE_CBC, ''))) {
return 'Failed to open encryption module: ' . OBFW_Exception();
}
if ($validate_key) {
// Get the IV size
$iv_size = mcrypt_enc_get_iv_size($this->cipher);
// Check header IV size - if incorrect it normally means wrong encryption type selected
if ($iv_size != $this->job['header']['iv_size']) {
return false;
}
$extra = 0;
// Generate the encryption key and password authentication value - allow $extra parameter to use a different section of the key
$dk = WPOnlineBackup_Functions::PBKDF2($this->progress['config']['enc_key'], $this->job['header']['iv'], 1148, $key_size * (2 + $extra) + 2);
$this->job['key'] = substr($dk, $extra ? $key_size * (1 + $extra) + 2 : 0, $key_size);
$pass_auth = substr($dk, $key_size * 2, 2);
$check_pass_auth = chr($this->job['header']['pass_auth1']) . chr($this->job['header']['pass_auth2']);
// While - so we can jump out
while ($pass_auth != $check_pass_auth) {
// Try the broken PBKDF2 call if this is a version 1 file
if ($this->job['header']['version'] == 1) {
$dk = WPOnlineBackup_Functions::PBKDF2_Broken($this->progress['config']['enc_key'], $this->job['header']['iv'], 1148, $key_size * (2 + $extra) + 2);
$this->job['key'] = substr($dk, $extra ? $key_size * (1 + $extra) + 2 : 0, $key_size);
$pass_auth = substr($dk, $key_size * 2, 2);
if ($pass_auth == $check_pass_auth) {
break;
}
}
// Password authentication didn't match
return false;
}
}
// Now initialise the cipher so we can start decrypting. Returns -2/-3 on errors, false on incorrect parameters
if (false === ($ret = @mcrypt_generic_init($this->cipher, $this->job['key'], $this->job['current_iv'])) || $ret < 0) {
return 'Failed to initialise encryption. PHP: ' . OBFW_Exception();
}
// Flag the cipher as initialised so we deinit it
$this->cipher_init = true;
return true;
}
