Encryption Class
+ +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 be provided with a high degree of security appropriate for storage.
+ + +Setting your Key
+ +A key is a piece of information that controls the cryptographic process and permits an encrypted string to be decoded. +In fact, the key you chose will provide the only means to decode data that was encrypted with that key, +so not only must you choose the key carefully, you must never change it if you intend use it for persistent data.
+ +It goes without saying that you should guard your key carefully. +Should someone gain access to your key, the data will be easily decoded. If your server is not totally under your control +it's impossible to ensure key security so you may want to think carefully before using it for anything +that requires high security, like storing credit card numbers.
+ +To take maximum advantage of the encryption algorithm, your key should be 32 characters in length (128 bits). +The key should be as random a string as you can concoct, with numbers and uppercase and lowercase letters. +Your key should not be a simple text string. In order to be cryptographically secure it +needs to be as random as possible.
+ +Your key can be either stored in your application/config/config.php, or you can design your own +storage mechanism and pass the key dynamically when encoding/decoding.
+ +To save your key to your application/config/config.php, open the file and set:
+$config['encryption_key'] = "YOUR KEY";
+
+
+Message Length
+ +It's important for you to know that the encoded messages the encryption function generates will be approximately 2.6 times longer than the original +message. For example, if you encrypt the string "my super secret data", which is 21 characters in length, you'll end up +with an encoded string that is roughly 55 characters (we say "roughly" because the encoded string length increments in +64 bit clusters, so it's not exactly linear). Keep this information in mind when selecting your data storage mechanism. Cookies, +for example, can only hold 4K of information.
+ + +Initializing the Class
+ +Like most other classes in CodeIgniter, the Encryption class is initialized in your controller using the $this->load->library function:
+ +$this->load->library('encrypt');
+Once loaded, the Encrypt library object will be available using: $this->encrypt
+ + +$this->encrypt->encode()
+ +Performs the data encryption and returns it as a string. Example:
+
+$msg = 'My secret message';
+
+$encrypted_string = $this->encrypt->encode($msg);
+
+You can optionally pass your encryption key via the second parameter if you don't want to use the one in your config file:
+ +
+$msg = 'My secret message';
+$key = 'super-secret-key';
+
+$encrypted_string = $this->encrypt->encode($msg, $key);
+
+
+$this->encrypt->decode()
+ +Decrypts an encoded string. Example:
+ +
+$encrypted_string = 'APANtByIGI1BpVXZTJgcsAG8GZl8pdwwa84';
+
+$plaintext_string = $this->encrypt->decode($encrypted_string);
+
+You can optionally pass your encryption key via the second parameter if you don't want to use the one in your config file:
+ +
+$msg = 'My secret message';
+$key = 'super-secret-key';
+
+$encrypted_string = $this->encrypt->decode($msg, $key);
+
+
+$this->encrypt->set_cipher();
+ +Permits you to set an Mcrypt cipher. By default it uses MCRYPT_RIJNDAEL_256. Example:
+$this->encrypt->set_cipher(MCRYPT_BLOWFISH);
+Please visit php.net for a list of available ciphers.
+ +If you'd like to manually test whether your server supports Mcrypt you can use:
+echo ( ! function_exists('mcrypt_encrypt')) ? 'Nope' : 'Yup';
+
+
+$this->encrypt->set_mode();
+ +Permits you to set an Mcrypt mode. By default it uses MCRYPT_MODE_CBC. Example:
+$this->encrypt->set_mode(MCRYPT_MODE_CFB);
+Please visit php.net for a list of available modes.
+ + +$this->encrypt->sha1();
+SHA1 encoding function. Provide a string and it will return a 160 bit one way hash. Note: SHA1, just like MD5 is non-decodable. Example:
+$hash = $this->encrypt->sha1('Some string');
+
+Many PHP installations have SHA1 support by default so if all you need is to encode a hash it's simpler to use the native +function:
+ +$hash = sha1('Some string');
+
+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);
+
+| Parameter | +Default | +Description | +
|---|---|---|
| $orig_data | +n/a | +The original encrypted data from CodeIgniter 1.x's Encryption library | +
| $legacy_mode | +MCRYPT_MODE_ECB | +The 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. | +
| $key | +n/a | +The encryption key. This it typically specified in your config file as outlined above. | +