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Merge pull request #754 from bantu/ssh2-function-key_exchange-reduction

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[1.0] SSH2: Add encryption_algorithm_to_key_size method.

* bantu/ssh2-function-key_exchange-reduction:
  Add encryption_algorithm_to_key_size method.
This commit is contained in:
Andreas Fischer 2015-07-27 22:08:06 +02:00
commit ee16fd44ce
1 changed files with 47 additions and 78 deletions
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125
phpseclib/Net/SSH2.php
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@ -1370,87 +1370,17 @@ class Net_SSH2
// we don't initialize any crypto-objects, yet - we do that, later. for now, we need the lengths to make the // we don't initialize any crypto-objects, yet - we do that, later. for now, we need the lengths to make the
// diffie-hellman key exchange as fast as possible // diffie-hellman key exchange as fast as possible
$decrypt = $this->_array_intersect_first($encryption_algorithms, $this->encryption_algorithms_server_to_client); $decrypt = $this->_array_intersect_first($encryption_algorithms, $this->encryption_algorithms_server_to_client);
switch ($decrypt) { $decryptKeyLength = $this->_encryption_algorithm_to_key_size($decrypt);
case '3des-cbc': if ($decryptKeyLength === null) {
case '3des-ctr': user_error('No compatible server to client encryption algorithms found');
$decryptKeyLength = 24; // eg. 192 / 8 return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
break;
case 'aes256-cbc':
case 'aes256-ctr':
case 'twofish-cbc':
case 'twofish256-cbc':
case 'twofish256-ctr':
$decryptKeyLength = 32; // eg. 256 / 8
break;
case 'aes192-cbc':
case 'aes192-ctr':
case 'twofish192-cbc':
case 'twofish192-ctr':
$decryptKeyLength = 24; // eg. 192 / 8
break;
case 'aes128-cbc':
case 'aes128-ctr':
case 'twofish128-cbc':
case 'twofish128-ctr':
case 'blowfish-cbc':
case 'blowfish-ctr':
$decryptKeyLength = 16; // eg. 128 / 8
break;
case 'arcfour':
case 'arcfour128':
$decryptKeyLength = 16; // eg. 128 / 8
break;
case 'arcfour256':
$decryptKeyLength = 32; // eg. 128 / 8
break;
case 'none':
$decryptKeyLength = 0;
break;
default:
user_error('No compatible server to client encryption algorithms found');
return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
} }
$encrypt = $this->_array_intersect_first($encryption_algorithms, $this->encryption_algorithms_client_to_server); $encrypt = $this->_array_intersect_first($encryption_algorithms, $this->encryption_algorithms_client_to_server);
switch ($encrypt) { $encryptKeyLength = $this->_encryption_algorithm_to_key_size($encrypt);
case '3des-cbc': if ($encryptKeyLength === null) {
case '3des-ctr': user_error('No compatible client to server encryption algorithms found');
$encryptKeyLength = 24; return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
break;
case 'aes256-cbc':
case 'aes256-ctr':
case 'twofish-cbc':
case 'twofish256-cbc':
case 'twofish256-ctr':
$encryptKeyLength = 32;
break;
case 'aes192-cbc':
case 'aes192-ctr':
case 'twofish192-cbc':
case 'twofish192-ctr':
$encryptKeyLength = 24;
break;
case 'aes128-cbc':
case 'aes128-ctr':
case 'twofish128-cbc':
case 'twofish128-ctr':
case 'blowfish-cbc':
case 'blowfish-ctr':
$encryptKeyLength = 16;
break;
case 'arcfour':
case 'arcfour128':
$encryptKeyLength = 16;
break;
case 'arcfour256':
$encryptKeyLength = 32;
break;
case 'none':
$encryptKeyLength = 0;
break;
default:
user_error('No compatible client to server encryption algorithms found');
return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
} }
$keyLength = $decryptKeyLength > $encryptKeyLength ? $decryptKeyLength : $encryptKeyLength; $keyLength = $decryptKeyLength > $encryptKeyLength ? $decryptKeyLength : $encryptKeyLength;
@ -1964,6 +1894,45 @@ class Net_SSH2
return true; return true;
} }
/**
* Maps an encryption algorithm name to the number of key bytes.
*
* @param String $algorithm Name of the encryption algorithm
* @return Mixed Number of bytes as an integer or null for unknown
* @access private
*/
function _encryption_algorithm_to_key_size($algorithm)
{
switch ($algorithm) {
case 'none':
return 0;
case 'aes128-cbc':
case 'aes128-ctr':
case 'arcfour':
case 'arcfour128':
case 'blowfish-cbc':
case 'blowfish-ctr':
case 'twofish128-cbc':
case 'twofish128-ctr':
return 16;
case '3des-cbc':
case '3des-ctr':
case 'aes192-cbc':
case 'aes192-ctr':
case 'twofish192-cbc':
case 'twofish192-ctr':
return 24;
case 'aes256-cbc':
case 'aes256-ctr':
case 'arcfour256':
case 'twofish-cbc':
case 'twofish256-cbc':
case 'twofish256-ctr':
return 32;
}
return null;
}
/** /**
* Login * Login
* *