From d8ff7c71bae0e83966163fa7487f2d04370fb907 Mon Sep 17 00:00:00 2001
From: vijayshinva <vijayshinva>
Date: Sat, 21 Nov 2020 11:34:38 +0530
Subject: [PATCH] Subresource Integrity

---
 Kryptos/Kryptos/Program.cs             |  3 +-
 Kryptos/Kryptos/WireUpSriExtensions.cs | 86 ++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 Kryptos/Kryptos/WireUpSriExtensions.cs

diff --git a/Kryptos/Kryptos/Program.cs b/Kryptos/Kryptos/Program.cs
index 6a66137..fec92ce 100644
--- a/Kryptos/Kryptos/Program.cs
+++ b/Kryptos/Kryptos/Program.cs
@@ -26,7 +26,8 @@ static async Task<int> Main(string[] args)
                 .WireUpHmacSha1Commands()
                 .WireUpHmacSha256Commands()
                 .WireUpHmacSha384Commands()
-                .WireUpHmacSha512Commands();
+                .WireUpHmacSha512Commands()
+                .WireUpSriCommands();
 
             return await rootCommand.InvokeAsync(args);
         }
diff --git a/Kryptos/Kryptos/WireUpSriExtensions.cs b/Kryptos/Kryptos/WireUpSriExtensions.cs
new file mode 100644
index 0000000..a558cfb
--- /dev/null
+++ b/Kryptos/Kryptos/WireUpSriExtensions.cs
@@ -0,0 +1,86 @@
+using System;
+using System.Collections.Generic;
+using System.CommandLine;
+using System.CommandLine.Invocation;
+using System.CommandLine.IO;
+using System.IO;
+using System.Net.Http;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace Kryptos
+{
+    public static class WireUpSriExtensions
+    {
+        public static RootCommand WireUpSriCommands(this RootCommand rootCommand)
+        {
+            var sriCommand = new Command("sri", "Subresource Integrity");
+            var sriHashCommand = new Command("hash", "Hash");
+            sriHashCommand.AddOption(new Option<string>(new string[] { "--text", "-t" }, "Input Text"));
+            sriHashCommand.AddOption(new Option<FileInfo>(new string[] { "--input", "-i" }, "Input file path"));
+            sriHashCommand.AddOption(new Option<Uri>(new string[] { "--uri", "-u" }, "Input Uri"));
+            sriHashCommand.AddOption(new Option<FileInfo>(new string[] { "--output", "-o" }, "Output file path"));
+            sriHashCommand.AddOption(new Option<int>(new string[] { "--sha" }, "256,384(default),512"));
+
+            sriHashCommand.Handler = CommandHandler.Create<int, string, FileInfo, Uri, FileInfo, IConsole>(async (sha, text, input, uri, output, console) =>
+            {
+                HashAlgorithm hashAlgorithm = null;
+                Stream inputStream = null;
+                try
+                {
+                    if (text != null)
+                    {
+                        inputStream = new MemoryStream(Encoding.UTF8.GetBytes(text));
+                    }
+                    if (input != null)
+                    {
+                        inputStream = input.OpenRead();
+                    }
+                    if (uri != null)
+                    {
+                        using var client = new HttpClient();
+                        inputStream = await client.GetStreamAsync(uri);
+                    }
+
+                    hashAlgorithm = sha switch
+                    {
+                        256 => SHA256.Create(),
+                        512 => SHA512.Create(),
+                        _ => SHA384.Create(),
+                    };
+
+                    var hashBytes = hashAlgorithm.ComputeHash(inputStream);
+                    var sri = $"sha{hashAlgorithm.HashSize}-{Convert.ToBase64String(hashBytes)}";
+                    if (output == null)
+                    {
+                        console.Out.WriteLine(sri);
+                    }
+                    else
+                    {
+                        await File.WriteAllTextAsync(output.FullName, sri).ConfigureAwait(false);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    console.Out.WriteLine(ex.Message);
+                }
+                finally
+                {
+                    if (inputStream != null)
+                    {
+                        await inputStream.DisposeAsync().ConfigureAwait(false);
+                    }
+                    if (hashAlgorithm != null)
+                    {
+                        hashAlgorithm.Dispose();
+                    }
+                }
+            });
+
+            sriCommand.Add(sriHashCommand);
+            rootCommand.AddCommand(sriCommand);
+
+            return rootCommand;
+        }
+    }
+}