Sodium (#9)

* wip: working on sodium implementation

* feature: initial sodium library implementation in object-oriented code
for #7

* test: message classes

* refactor: remove unused class

* refactor: remove unused uri classes

* test: cipher & init vector

* test: key pair - 100% coverage

* feature: encrypted uri

* tweak: don't pass unused public key

* tweak: remove unused import

* test: fix tests after refactor

* refactor: only use psr standard functionality

* refactor: automatically generate key's bytes

* refactor: secretbox sodium.php

* refactor: secretbox sodium.php

* refactor: secretbox sodium-lib-uri.php

* refactor: secretbox remove unused references

* refactor: no need to pass shared key as it's already in the uri

* test: EncryptedMessage

* test: tests passing

* feature: do not pass key in uri

* test: cipher text geturi

* test: key

* test: EncryptedUri - 100% coverage

* tweak: output shared key with uri

* tweak: use cipher test uri

* stan: remove unused key

* docs: update readme

Author: Greg Bowler

README.md

@@ -1,13 +1,13 @@
 Two-way encryption of messages for secure plain text transmission.
 ==================================================================
 
-When messages are passed between two systems via a public network, encryption tools must be used to secure the communication channel. The process of encrypting and decrypting a message is complex and prone to errors, but is simplified in this repository by providing the `Message` and `EncryptedMessage` class abstractions.
+When messages are passed between two systems via a public network, encryption tools must be used to secure the communication channel. The process of encrypting and decrypting a message is complex and prone to errors, but is simplified in this repository by providing the `PlainTextMessage` and `EncryptedMessage` class abstractions.
 
-Pass your plain text message to the `Message` constructor along with a private key, and you can call `getCipherText()` and `getIv()`. These two strings can be passed to the receiver by any communication mechanism, safe in the knowledge that the contents can not be read without the private key.
+Pass your secret message to the `PlainTextMessage` constructor along with a private key, and you can call `encrypt()` to convert it into an `EncryptedMessage`. An `EncryptedMessage` is represented by a Cipher and IV value via the `getCipherText()` and `getIv()` functions. These two strings can be passed to the receiver by any communication mechanism, safe in the knowledge that the contents can not be read without the private key.
 
-On the receiver, construct an `EncryptedMessage` with the incoming ciphertext, and the same private key and IV, and the original message can be read. 
+On the receiver, construct another `EncryptedMessage` with the incoming cipher and IV, and the original message can be read using `decrypt()` 
 
-The `URIAdapter` class can be used to convert from a `Message` to a URI query string, or from a URI to an `EncryptedMessage`. 
+The `CipherText` class also exposes a `getUri()` function, for creating a pre-encoded URI. A URI with `cipher` and `iv` querystring parameters can be passed to the `EncryptedUri` class to decrypt back into a `PlainTextMessage`.
 
 ***
 
@@ -32,20 +32,26 @@ The `URIAdapter` class can be used to convert from a `Message` to a URI query st
 `sender.php`:
 
 ```php
-$message = "Hello, PHP.Gt!";
+use \Gt\Cipher\Message\PlainTextMessage;
+use \Gt\Cipher\Message\EncryptedMessage;
+
 $privateKey = "This can be any string, but a long random string is best.";
 
-$message = new \Gt\Cipher\Message\PlainTextMessage($message, $privateKey);
-// Redirect to receiver.php, possibly on another server:
-header("Location: " . new \Gt\Cipher\CipherUri($message, "/receiver.php"));
+$message = new PlainTextMessage("Hello, PHP.Gt!");
+$cipherText = $message->encrypt($privateKey);
+header("Location: " . $cipherText->getUri("/receiver.php"));
 ```
 
 `receiver.php`:
 
 ```php
 // This key must be the same on the sender and receiver!
+use Gt\Cipher\EncryptedUri;
+
 $privateKey = "This can be any string, but a long random string is best.";
-$cipher = new \Gt\Cipher\Message\EncryptedMessage($_GET["cipher"], $_GET["iv"], $privateKey);
-echo $cipher->getMessage();
+
+$uri = new EncryptedUri($_SERVER["REQUEST_URI"]);
+$plainText = $uri->decryptMessage($privateKey);
+echo $plainText;
 // Output: Hello, PHP.Gt!
 ```