v2: Updates

* Simplifies & beautifies everything
* Introduces a new Class system.
* Errors are defaulted to AWS's handler.
* New function names & more efficient handling.
* Should fix a majority of the errors.

Please read the README for more!

aws/Aws/Crypto/Cipher/CipherBuilderTrait.php

@@ -0,0 +1,72 @@
+<?php
+namespace Aws\Crypto\Cipher;
+
+use Aws\Exception\CryptoException;
+
+trait CipherBuilderTrait
+{
+    /**
+     * Returns an identifier recognizable by `openssl_*` functions, such as
+     * `aes-256-cbc` or `aes-128-ctr`.
+     *
+     * @param string $cipherName Name of the cipher being used for encrypting
+     *                           or decrypting.
+     * @param int $keySize Size of the encryption key, in bits, that will be
+     *                     used.
+     *
+     * @return string
+     */
+    protected function getCipherOpenSslName($cipherName, $keySize)
+    {
+        return "aes-{$keySize}-{$cipherName}";
+    }
+
+    /**
+     * Constructs a CipherMethod for the given name, initialized with the other
+     * data passed for use in encrypting or decrypting.
+     *
+     * @param string $cipherName Name of the cipher to generate for encrypting.
+     * @param string $iv Base Initialization Vector for the cipher.
+     * @param int $keySize Size of the encryption key, in bits, that will be
+     *                     used.
+     *
+     * @return CipherMethod
+     *
+     * @internal
+     */
+    protected function buildCipherMethod($cipherName, $iv, $keySize)
+    {
+        switch ($cipherName) {
+            case 'cbc':
+                return new Cbc(
+                    $iv,
+                    $keySize
+                );
+            default:
+                return null;
+        }
+    }
+
+    /**
+     * Performs a reverse lookup to get the openssl_* cipher name from the
+     * AESName passed in from the MetadataEnvelope.
+     *
+     * @param $aesName
+     *
+     * @return string
+     *
+     * @internal
+     */
+    protected function getCipherFromAesName($aesName)
+    {
+        switch ($aesName) {
+            case 'AES/GCM/NoPadding':
+                return 'gcm';
+            case 'AES/CBC/PKCS5Padding':
+                return 'cbc';
+            default:
+                throw new CryptoException('Unrecognized or unsupported'
+                    . ' AESName for reverse lookup.');
+        }
+    }
+}