runff 1.0 commit

lib/aws/Aws/Crypto/Cipher/Cbc.php

@@ -0,0 +1,82 @@
+<?php
+namespace Aws\Crypto\Cipher;
+
+use \InvalidArgumentException;
+use \LogicException;
+
+/**
+ * An implementation of the CBC cipher for use with an AesEncryptingStream or
+ * AesDecrypting stream.
+ */
+class Cbc implements CipherMethod
+{
+    const BLOCK_SIZE = 16;
+
+    /**
+     * @var string
+     */
+    private $baseIv;
+
+    /**
+     * @var string
+     */
+    private $iv;
+
+    /**
+     * @var int
+     */
+    private $keySize;
+
+    /**
+     * @param string $iv Base Initialization Vector for the cipher.
+     * @param int $keySize Size of the encryption key, in bits, that will be
+     *                     used.
+     *
+     * @throws InvalidArgumentException Thrown if the passed iv does not match
+     *                                  the iv length required by the cipher.
+     */
+    public function __construct($iv, $keySize = 256)
+    {
+        $this->baseIv = $this->iv = $iv;
+        $this->keySize = $keySize;
+
+        if (strlen($iv) !== openssl_cipher_iv_length($this->getOpenSslName())) {
+            throw new InvalidArgumentException('Invalid initialization vector');
+        }
+    }
+
+    public function getOpenSslName()
+    {
+        return "aes-{$this->keySize}-cbc";
+    }
+
+    public function getAesName()
+    {
+        return 'AES/CBC/PKCS5Padding';
+    }
+
+    public function getCurrentIv()
+    {
+        return $this->iv;
+    }
+
+    public function requiresPadding()
+    {
+        return true;
+    }
+
+    public function seek($offset, $whence = SEEK_SET)
+    {
+        if ($offset === 0 && $whence === SEEK_SET) {
+            $this->iv = $this->baseIv;
+        } else {
+            throw new LogicException('CBC initialization only support being'
+                . ' rewound, not arbitrary seeking.');
+        }
+    }
+
+    public function update($cipherTextBlock)
+    {
+        $this->iv = substr($cipherTextBlock, self::BLOCK_SIZE * -1);
+    }
+}