Add CRC32 hashing

src/nHash/Features/HashAlgorithmFeature.cs

@@ -1,4 +1,5 @@
 using System.Security.Cryptography;
+using nHash.Providers.Hashing;
 
 namespace nHash.Features;
 
@@ -55,13 +56,14 @@ private static void CalculateText(string text, bool lowerCase, string fileName)
 
     private static void CalculateHash(byte[] inputBytes, bool lowerCase)
     {
-        var algorithms = new Dictionary<string, HashAlgorithm>()
+        var algorithms = new Dictionary<string, IHash>()
         {
-            { "MD5", MD5.Create() },
-            { "SHA-1", SHA1.Create() },
-            { "SHA-256", SHA256.Create() },
-            { "SHA-384", SHA384.Create() },
-            { "SHA-512", SHA512.Create() }
+            { "MD5", new MD5Hash() },
+            { "SHA-1", new SHA1Hash() },
+            { "SHA-256", new SHA256Hash() },
+            { "SHA-384", new SHA384Hash() },
+            { "SHA-512", new SHA512Hash() },
+            { "CRC32", new CRC32Hash() }
         };
 
         foreach (var algorithm in algorithms)

src/nHash/Providers/Hashing/CRC32Hash.cs

@@ -0,0 +1,39 @@
+namespace nHash.Providers.Hashing;
+
+public class CRC32Hash : IHash
+{
+    private readonly uint[] _checksumTable;
+    private const uint Polynomial = 0xEDB88320;
+
+    public CRC32Hash()
+    {
+        _checksumTable = new uint[0x100];
+
+        for (uint index = 0; index < 0x100; ++index)
+        {
+            var item = index;
+            for (int bit = 0; bit < 8; ++bit)
+                item = ((item & 1) != 0) ? (Polynomial ^ (item >> 1)) : (item >> 1);
+            _checksumTable[index] = item;
+        }
+    }
+
+    public byte[] ComputeHash(byte[] buffer)
+    {
+        using var stream = new MemoryStream(buffer);
+        return ComputeHash(stream);
+    }
+
+    private byte[] ComputeHash(Stream stream)
+    {
+        var result = 0xFFFFFFFF;
+
+        int current;
+        while ((current = stream.ReadByte()) != -1)
+            result = _checksumTable[(result & 0xFF) ^ (byte)current] ^ (result >> 8);
+
+        var hash = BitConverter.GetBytes(~result);
+        Array.Reverse(hash);
+        return hash;
+    }
+}

src/nHash/Providers/Hashing/IHash.cs

@@ -0,0 +1,6 @@
+namespace nHash.Providers.Hashing;
+
+public interface IHash
+{
+    public byte[] ComputeHash(byte[] buffer);
+}

src/nHash/Providers/Hashing/MD5Hash.cs

@@ -0,0 +1,13 @@
+using System.Security.Cryptography;
+
+namespace nHash.Providers.Hashing;
+
+public class MD5Hash : IHash
+{
+    private readonly MD5 _provider = MD5.Create();
+
+    public byte[] ComputeHash(byte[] buffer)
+    {
+        return _provider.ComputeHash(buffer);
+    }
+}

src/nHash/Providers/Hashing/SHA1Hash.cs

@@ -0,0 +1,13 @@
+using System.Security.Cryptography;
+
+namespace nHash.Providers.Hashing;
+
+public class SHA1Hash : IHash
+{
+    private readonly SHA1 _provider = SHA1.Create();
+
+    public byte[] ComputeHash(byte[] buffer)
+    {
+        return _provider.ComputeHash(buffer);
+    }
+}

src/nHash/Providers/Hashing/SHA256Hash.cs

@@ -0,0 +1,13 @@
+using System.Security.Cryptography;
+
+namespace nHash.Providers.Hashing;
+
+public class SHA256Hash : IHash
+{
+    private readonly SHA256 _provider = SHA256.Create();
+
+    public byte[] ComputeHash(byte[] buffer)
+    {
+        return _provider.ComputeHash(buffer);
+    }
+}

src/nHash/Providers/Hashing/SHA384Hash.cs

@@ -0,0 +1,13 @@
+using System.Security.Cryptography;
+
+namespace nHash.Providers.Hashing;
+
+public class SHA384Hash : IHash
+{
+    private readonly SHA384 _provider = SHA384.Create();
+
+    public byte[] ComputeHash(byte[] buffer)
+    {
+        return _provider.ComputeHash(buffer);
+    }
+}

src/nHash/Providers/Hashing/SHA512Hash.cs

@@ -0,0 +1,13 @@
+using System.Security.Cryptography;
+
+namespace nHash.Providers.Hashing;
+
+public class SHA512Hash : IHash
+{
+    private readonly SHA512 _provider = SHA512.Create();
+
+    public byte[] ComputeHash(byte[] buffer)
+    {
+        return _provider.ComputeHash(buffer);
+    }
+}

src/nHash/nHash.csproj

@@ -16,4 +16,8 @@
         <PackageReference Include="Humanizer.Core" Version="2.14.1" />
         <PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />
     </ItemGroup>
+
+    <ItemGroup>
+      <Folder Include="Helpers" />
+    </ItemGroup>
 </Project>