From d3a4753b79c84ffefde136b49e5944770047c964 Mon Sep 17 00:00:00 2001
From: Jonas Hermsmeier <jhermsmeier@gmail.com>
Date: Fri, 27 Apr 2018 21:49:43 +0200
Subject: [PATCH] feat(writer): Use xxHash instead of SHA512 for verification

This switches from SHA512 to xxHash for verification hashing,
as xxHash provides more throughput.

Change-Type: patch
---
 lib/cli/etcher.js                   |  4 ++--
 lib/gui/app/modules/image-writer.js |  2 +-
 lib/sdk/writer/checksum-stream.js   | 12 +++++++++++-
 npm-shrinkwrap.json                 |  4 ++++
 package.json                        |  1 +
 5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/lib/cli/etcher.js b/lib/cli/etcher.js
index c9df30aa..5ce0d432 100644
--- a/lib/cli/etcher.js
+++ b/lib/cli/etcher.js
@@ -99,7 +99,7 @@ permissions.isElevated().then((elevated) => {
     const writer = new ImageWriter({
       verify: options.check,
       unmountOnSuccess: options.unmount,
-      checksumAlgorithms: options.check ? [ 'sha512' ] : []
+      checksumAlgorithms: options.check ? [ 'xxhash' ] : []
     })
 
     /**
@@ -133,7 +133,7 @@ permissions.isElevated().then((elevated) => {
         exitCode = EXIT_CODES.GENERAL_ERROR
         console.log(`  - ${result.device.device}: ${result.error.message}`)
       } else {
-        console.log(`  - ${result.device.device}: ${result.checksum.sha512}`)
+        console.log(`  - ${result.device.device}: ${result.checksum.xxhash}`)
       }
     })
   }
diff --git a/lib/gui/app/modules/image-writer.js b/lib/gui/app/modules/image-writer.js
index 026012b8..e5825916 100644
--- a/lib/gui/app/modules/image-writer.js
+++ b/lib/gui/app/modules/image-writer.js
@@ -147,7 +147,7 @@ exports.performWrite = (image, drives, onProgress) => {
         destinations: drives,
         validateWriteOnSuccess: settings.get('validateWriteOnSuccess'),
         unmountOnSuccess: settings.get('unmountOnSuccess'),
-        checksumAlgorithms: [ 'sha512' ]
+        checksumAlgorithms: [ 'xxhash' ]
       })
     })
 
diff --git a/lib/sdk/writer/checksum-stream.js b/lib/sdk/writer/checksum-stream.js
index 68e33cee..634ada7c 100644
--- a/lib/sdk/writer/checksum-stream.js
+++ b/lib/sdk/writer/checksum-stream.js
@@ -18,6 +18,7 @@
 
 const stream = require('readable-stream')
 const crypto = require('crypto')
+const xxhash = require('xxhash')
 const _ = require('lodash')
 
 /**
@@ -66,7 +67,16 @@ class ChecksumStream extends stream.Transform {
    * const hash = this._createHash(algorithm)
    */
   _createHash (algorithm) {
-    const hash = _.attempt(crypto.createHash, algorithm)
+    let hash = null
+
+    if (algorithm === 'xxhash') {
+      // Seed value 0x45544348 = ASCII "ETCH"
+      const seed = 0x45544348
+      const is64Bit = process.arch === 'x64' || process.arch === 'aarch64'
+      hash = new xxhash.Stream(seed, is64Bit ? 64 : 32)
+    } else {
+      hash = _.attempt(crypto.createHash, algorithm)
+    }
 
     if (_.isError(hash)) {
       hash.message += ` "${algorithm}"`
diff --git a/npm-shrinkwrap.json b/npm-shrinkwrap.json
index c5f71ad3..9dff693c 100644
--- a/npm-shrinkwrap.json
+++ b/npm-shrinkwrap.json
@@ -9081,6 +9081,10 @@
       "resolved": "https://registry.npmjs.org/xtend/-/xtend-2.1.2.tgz",
       "dev": true
     },
+    "xxhash": {
+      "version": "0.2.4",
+      "resolved": "https://registry.npmjs.org/xxhash/-/xxhash-0.2.4.tgz"
+    },
     "y18n": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/y18n/-/y18n-3.2.1.tgz"
diff --git a/package.json b/package.json
index 7fa1f6df..cdaefa33 100644
--- a/package.json
+++ b/package.json
@@ -89,6 +89,7 @@
     "uuid": "3.0.1",
     "winusb-driver-generator": "1.1.7",
     "xml2js": "0.4.17",
+    "xxhash": "0.2.4",
     "yargs": "11.0.0",
     "yauzl": "2.6.0"
   },