From 387af7eb600fcab56a04b4184d53eb0fe509e30b Mon Sep 17 00:00:00 2001
From: Roeland Jago Douma <roeland@famdouma.nl>
Date: Mon, 11 May 2020 10:31:46 +0200
Subject: [PATCH] Use random_bytes

Since we don't care if it is human readbale.
The code is backwards compatible with the old format.

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>
---
 lib/private/Security/Crypto.php   | 20 +++++++++++++-------
 tests/lib/Security/CryptoTest.php | 15 +++++++++++----
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/lib/private/Security/Crypto.php b/lib/private/Security/Crypto.php
index 10a52d9fc8..154448281b 100644
--- a/lib/private/Security/Crypto.php
+++ b/lib/private/Security/Crypto.php
@@ -52,17 +52,14 @@ class Crypto implements ICrypto {
 	private $ivLength = 16;
 	/** @var IConfig */
 	private $config;
-	/** @var ISecureRandom */
-	private $random;
 
 	/**
 	 * @param IConfig $config
 	 * @param ISecureRandom $random
 	 */
-	public function __construct(IConfig $config, ISecureRandom $random) {
+	public function __construct(IConfig $config) {
 		$this->cipher = new AES();
 		$this->config = $config;
-		$this->random = $random;
 	}
 
 	/**
@@ -95,13 +92,14 @@ class Crypto implements ICrypto {
 		}
 		$this->cipher->setPassword($password);
 
-		$iv = $this->random->generate($this->ivLength);
+		$iv = \random_bytes($this->ivLength);
 		$this->cipher->setIV($iv);
 
 		$ciphertext = bin2hex($this->cipher->encrypt($plaintext));
+		$iv = bin2hex($iv);
 		$hmac = bin2hex($this->calculateHMAC($ciphertext.$iv, $password));
 
-		return $ciphertext.'|'.$iv.'|'.$hmac;
+		return $ciphertext.'|'.$iv.'|'.$hmac.'|2';
 	}
 
 	/**
@@ -119,7 +117,8 @@ class Crypto implements ICrypto {
 		$this->cipher->setPassword($password);
 
 		$parts = explode('|', $authenticatedCiphertext);
-		if (\count($parts) !== 3) {
+		$partCount = \count($parts);
+		if ($partCount < 3 || $partCount > 4) {
 			throw new \Exception('Authenticated ciphertext could not be decoded.');
 		}
 
@@ -127,6 +126,13 @@ class Crypto implements ICrypto {
 		$iv = $parts[1];
 		$hmac = hex2bin($parts[2]);
 
+		if ($partCount === 4) {
+			$version = $parts[3];
+			if ($version === '2') {
+				$iv = hex2bin($iv);
+			}
+		}
+
 		$this->cipher->setIV($iv);
 
 		if (!hash_equals($this->calculateHMAC($parts[0] . $parts[1], $password), $hmac)) {
diff --git a/tests/lib/Security/CryptoTest.php b/tests/lib/Security/CryptoTest.php
index a6f4902594..dbdf6f6a19 100644
--- a/tests/lib/Security/CryptoTest.php
+++ b/tests/lib/Security/CryptoTest.php
@@ -24,7 +24,7 @@ class CryptoTest extends \Test\TestCase {
 
 	protected function setUp(): void {
 		parent::setUp();
-		$this->crypto = new Crypto(\OC::$server->getConfig(), \OC::$server->getSecureRandom());
+		$this->crypto = new Crypto(\OC::$server->getConfig());
 	}
 
 	/**
@@ -35,7 +35,7 @@ class CryptoTest extends \Test\TestCase {
 		$this->assertEquals($stringToEncrypt, $this->crypto->decrypt($ciphertext));
 	}
 
-	
+
 	public function testWrongPassword() {
 		$this->expectException(\Exception::class);
 		$this->expectExceptionMessage('HMAC does not match.');
@@ -51,7 +51,7 @@ class CryptoTest extends \Test\TestCase {
 		$this->assertEquals($stringToEncrypt, $this->crypto->decrypt($encryptedString, 'ThisIsAVeryS3cur3P4ssw0rd'));
 	}
 
-	
+
 	public function testWrongIV() {
 		$this->expectException(\Exception::class);
 		$this->expectExceptionMessage('HMAC does not match.');
@@ -60,7 +60,7 @@ class CryptoTest extends \Test\TestCase {
 		$this->crypto->decrypt($encryptedString, 'ThisIsAVeryS3cur3P4ssw0rd');
 	}
 
-	
+
 	public function testWrongParameters() {
 		$this->expectException(\Exception::class);
 		$this->expectExceptionMessage('Authenticated ciphertext could not be decoded.');
@@ -68,4 +68,11 @@ class CryptoTest extends \Test\TestCase {
 		$encryptedString = '1|2';
 		$this->crypto->decrypt($encryptedString, 'ThisIsAVeryS3cur3P4ssw0rd');
 	}
+
+	public function testLegacy() {
+		$cipherText = 'e16599188e3d212f5c7f17fdc2abca46|M1WfLAxbcAmITeD6|509457885d6ca5e6c3bfd3741852687a7f2bffce197f8d5ae97b65818b15a1b7f616b68326ff312371540f4ca8ac55f8e2de4aa13aab3474bd3431e51214e3ee';
+		$password = 'mypass';
+
+		$this->assertSame('legacy test', $this->crypto->decrypt($cipherText, $password));
+	}
 }