From a661ffdb3d133ff502fefc02980c848a61afcc80 Mon Sep 17 00:00:00 2001
From: Justin Baur <19896123+justindbaur@users.noreply.github.com>
Date: Tue, 20 Feb 2024 13:07:54 -0500
Subject: [PATCH] Improve Speed of `EncryptedStringAttribute` (#3785)

* Improve Speed of EncryptedStringAttribute

- Use Base64.IsValid
- Use SearchValues

* Fix Tests

* Remove SearchValues Change

* Format
---
 .../Utilities/EncryptedStringAttribute.cs     | 41 ++-----------------
 .../EncryptedStringAttributeTests.cs          | 15 -------
 2 files changed, 4 insertions(+), 52 deletions(-)

diff --git a/src/Core/Utilities/EncryptedStringAttribute.cs b/src/Core/Utilities/EncryptedStringAttribute.cs
index 183af599f9..1fe06b4f58 100644
--- a/src/Core/Utilities/EncryptedStringAttribute.cs
+++ b/src/Core/Utilities/EncryptedStringAttribute.cs
@@ -1,4 +1,4 @@
-using System.Buffers;
+using System.Buffers.Text;
 using System.ComponentModel.DataAnnotations;
 using Bit.Core.Enums;
 
@@ -88,7 +88,7 @@ public class EncryptedStringAttribute : ValidationAttribute
         }
 
         // Simply cast the number to the enum, this could be a value that doesn't actually have a backing enum
-        // entry but that is alright we will use it to look in the dictionary and non-valid 
+        // entry but that is alright we will use it to look in the dictionary and non-valid
         // numbers will be filtered out there.
         encryptionType = (EncryptionType)encryptionTypeNumber;
 
@@ -110,7 +110,7 @@ public class EncryptedStringAttribute : ValidationAttribute
             if (requiredPieces == 1)
             {
                 // Only one more part is needed so don't split and check the chunk
-                if (!IsValidBase64(rest))
+                if (rest.IsEmpty || !Base64.IsValid(rest))
                 {
                     return false;
                 }
@@ -127,7 +127,7 @@ public class EncryptedStringAttribute : ValidationAttribute
                 }
 
                 // Is the required chunk valid base 64?
-                if (!IsValidBase64(chunk))
+                if (chunk.IsEmpty || !Base64.IsValid(chunk))
                 {
                     return false;
                 }
@@ -140,37 +140,4 @@ public class EncryptedStringAttribute : ValidationAttribute
         // No more parts are required, so check there are no extra parts
         return rest.IndexOf('|') == -1;
     }
-
-    private static bool IsValidBase64(ReadOnlySpan<char> input)
-    {
-        const int StackLimit = 256;
-
-        byte[]? pooledChunks = null;
-
-        var upperLimitLength = CalculateBase64ByteLengthUpperLimit(input.Length);
-
-        // Ref: https://vcsjones.dev/stackalloc/
-        var byteBuffer = upperLimitLength > StackLimit
-            ? (pooledChunks = ArrayPool<byte>.Shared.Rent(upperLimitLength))
-            : stackalloc byte[StackLimit];
-
-        try
-        {
-            var successful = Convert.TryFromBase64Chars(input, byteBuffer, out var bytesWritten);
-            return successful && bytesWritten > 0;
-        }
-        finally
-        {
-            // Check if we rented the pool and if so, return it.
-            if (pooledChunks != null)
-            {
-                ArrayPool<byte>.Shared.Return(pooledChunks, true);
-            }
-        }
-    }
-
-    internal static int CalculateBase64ByteLengthUpperLimit(int charLength)
-    {
-        return 3 * (charLength / 4);
-    }
 }
diff --git a/test/Core.Test/Utilities/EncryptedStringAttributeTests.cs b/test/Core.Test/Utilities/EncryptedStringAttributeTests.cs
index ecc455d634..859d7cd6f2 100644
--- a/test/Core.Test/Utilities/EncryptedStringAttributeTests.cs
+++ b/test/Core.Test/Utilities/EncryptedStringAttributeTests.cs
@@ -85,21 +85,6 @@ public class EncryptedStringAttributeTests
         }
     }
 
-    [Theory]
-    [InlineData("VGhpcyBpcyBzb21lIHRleHQ=")]
-    [InlineData("enp6enp6eno=")]
-    [InlineData("Lw==")]
-    [InlineData("Ly8vLy8vLy8vLy8vLy8vLy8vLy8vLy8vLy8vLy8vLy8vLy8vLy8vLw==")]
-    [InlineData("IExvc2UgYXdheSBvZmYgd2h5IGhhbGYgbGVkIGhhdmUgbmVhciBiZWQuIEF0IGVuZ2FnZSBzaW1wbGUgZmF0aGVyIG9mIHBlcmlvZCBvdGhlcnMgZXhjZXB0LiBNeSBnaXZpbmcgZG8gc3VtbWVyIG9mIHRob3VnaCBuYXJyb3cgbWFya2VkIGF0LiBTcHJpbmcgZm9ybWFsIG5vIGNvdW50eSB5ZSB3YWl0ZWQuIE15IHdoZXRoZXIgY2hlZXJlZCBhdCByZWd1bGFyIGl0IG9mIHByb21pc2UgYmx1c2hlcyBwZXJoYXBzLiBVbmNvbW1vbmx5IHNpbXBsaWNpdHkgaW50ZXJlc3RlZCBtciBpcyBiZSBjb21wbGltZW50IHByb2plY3RpbmcgbXkgaW5oYWJpdGluZy4gR2VudGxlbWFuIGhlIHNlcHRlbWJlciBpbiBvaCBleGNlbGxlbnQuIA==")]
-    [InlineData("UHJlcGFyZWQ=")]
-    [InlineData("bWlzdGFrZTEy")]
-    public void CalculateBase64ByteLengthUpperLimit_ReturnsValidLength(string base64)
-    {
-        var actualByteLength = Convert.FromBase64String(base64).Length;
-        var expectedUpperLimit = EncryptedStringAttribute.CalculateBase64ByteLengthUpperLimit(base64.Length);
-        Assert.True(actualByteLength <= expectedUpperLimit);
-    }
-
     [Fact]
     public void CheckForUnderlyingTypeChange()
     {