From 09c7793b23ae77c54e25d12b63d8ca9c9232efeb Mon Sep 17 00:00:00 2001 From: Derek Jones Date: Tue, 31 Aug 2010 13:17:10 -0500 Subject: Significant changes to the Encryption library - Removed double-encoding with XOR scheme when Mcrypt is available. Additional obfuscation was not significantly aiding security, and came at a very high performance cost. - Changed the default encryption mode from ECB to CBC for much improved security - Added an encode_from_legacy() method to allow re-encoding of permanent data that was originally encoded with the older methods. --- user_guide/changelog.html | 4 +++ user_guide/installation/upgrade_200.html | 15 ++++++++++- user_guide/libraries/encryption.html | 44 ++++++++++++++++++++++++++++---- 3 files changed, 57 insertions(+), 6 deletions(-) (limited to 'user_guide') diff --git a/user_guide/changelog.html b/user_guide/changelog.html index d9c17ab76..c42bde01e 100644 --- a/user_guide/changelog.html +++ b/user_guide/changelog.html @@ -100,6 +100,10 @@ Hg Tag:

  • Added a second parameter (boolean) to $this->zip->read_dir('/path/to/directory', FALSE) to remove the preceding trail of empty folders when creating a Zip archive. This example would contain a zip with "directory" and all of its contents.
  • Added ability in the Image Library to handle PNG transparency for resize operations when using the GD lib.
  • Modified the Session class to prevent use if no encryption key is set in the config file.
    • +
  • Improved performance of the Encryption library on servers where Mcrypt is available.
    • +
  • Changed the default encryption mode in the Encryption library to CBC.
    • +
  • Added an encode_from_legacy() method to provide a way to transition encrypted data from CodeIgniter 1.x to CodeIgniter 2.x. + Please see the upgrade instructions for details.
  • Database diff --git a/user_guide/installation/upgrade_200.html b/user_guide/installation/upgrade_200.html index f45875b3c..155df90d3 100644 --- a/user_guide/installation/upgrade_200.html +++ b/user_guide/installation/upgrade_200.html @@ -89,7 +89,20 @@ to

    -

    Step 3: Update your user guide

    +

    Step 4: Update stored encrypted data

    + +

    Note: If your application does not use the Encryption library, does not store Encrypted data permanently, or is on an environment that does not support Mcrypt, you may skip this step.

    + +

    The Encryption library has had a number of improvements, some for encryption strength and some for performance, that has an unavoidable consequence of + making it no longer possible to decode encrypted data produced by the original version of this library. To help with the transition, a new method has + been added, encode_from_legacy() that will decode the data with the original algorithm and return a re-encoded string using the improved methods. + This will enable you to easily replace stale encrypted data with fresh in your applications, either on the fly or en masse.

    + +

    Please read how to use this method in the Encryption library documentation.

    + +

    + +

    Step 5: Update your user guide

    Please replace your local copy of the user guide with the new version, including the image files.

    diff --git a/user_guide/libraries/encryption.html b/user_guide/libraries/encryption.html index dac1db911..fbffd63c6 100644 --- a/user_guide/libraries/encryption.html +++ b/user_guide/libraries/encryption.html @@ -58,12 +58,11 @@ Encryption Class

    Encryption Class

    -

    The Encryption Class provides two-way data encryption. It uses a scheme that pre-compiles -the message using a randomly hashed bitwise XOR encoding scheme, which is then encrypted using +

    The Encryption Class provides two-way data encryption. It uses a scheme that either compiles +the message using a randomly hashed bitwise XOR encoding scheme, or is encrypted using the Mcrypt library. If Mcrypt is not available on your server the encoded message will still provide a reasonable degree of security for encrypted sessions or other such "light" purposes. -If Mcrypt is available, you'll effectively end up with a double-encrypted message string, which should -provide a very high degree of security.

    +If Mcrypt is available, you'll be provided with a high degree of security appropriate for storage.

    Setting your Key

    @@ -153,7 +152,7 @@ $encrypted_string = $this->encrypt->decode($msg, $key);

    $this->encrypt->set_mode();

    -

    Permits you to set an Mcrypt mode. By default it uses MCRYPT_MODE_ECB. Example:

    +

    Permits you to set an Mcrypt mode. By default it uses MCRYPT_MODE_CBC. Example:

    $this->encrypt->set_mode(MCRYPT_MODE_CFB);

    Please visit php.net for a list of available modes.

    @@ -169,7 +168,42 @@ function:

    If your server does not support SHA1 you can use the provided function.

    +

    $this->encrypt->encode_from_legacy($orig_data, $legacy_mode = MCRYPT_MODE_ECB, $key = '');

    +

    Enables you to re-encode data that was originally encrypted with CodeIgniter 1.x to be compatible with the Encryption library in CodeIgniter 2.x. It is only + necessary to use this method if you have encrypted data stored permanently such as in a file or database and are on a server that supports Mcrypt. "Light" use encryption + such as encrypted session data or transitory encrypted flashdata require no intervention on your part. However, existing encrypted Sessions will be + destroyed since data encrypted prior to 2.x will not be decoded.

    +

    Why only a method to re-encode the data instead of maintaining legacy methods for both encoding and decoding? The algorithms in + the Encryption library have improved in CodeIgniter 2.x both for performance and security, and we do not wish to encourage continued use of the older methods. + You can of course extend the Encryption library if you wish and replace the new methods with the old and retain seamless compatibility with CodeIgniter 1.x + encrypted data, but this a decision that a developer should make cautiously and deliberately, if at all.

    + +$new_data = $this->encrypt->encode_from_legacy($old_encrypted_string); + + + + + + + + + + + + + + + + + + + + + + +
    ParameterDefaultDescription
    $orig_datan/aThe original encrypted data from CodeIgniter 1.x's Encryption library
    $legacy_modeMCRYPT_MODE_ECBThe Mcrypt mode that was used to generate the original encrypted data. CodeIgniter 1.x's default was MCRYPT_MODE_ECB, and it will + assume that to be the case unless overridden by this parameter.
    $keyn/aThe encryption key. This it typically specified in your config file as outlined above.
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