Add HMAC Filters

Fluid.Tests/MiscFiltersTests.cs

@@ -913,6 +913,50 @@ public async Task Sha256()
             Assert.Equal("c7ac4687585ab5d3d5030db5a5cfc959fdf4e608cc396f1f615db345e35adb9e", result.ToStringValue());
         }
 
+        [Theory]
+        [InlineData(null, "Fluid", "")]
+        [InlineData("secret_key", null, "")]
+        [InlineData("", "", "fbdb1d1b18aa6c08324b7d64b71fb76370690e1d")]
+        [InlineData("", "Fluid", "47ab4d87fabf7a7162d59c57298780904de9e245")]
+        [InlineData("secret_key", "Fluid", "1061ea276551355150b8581aa64dca829d41e357")]
+        public async Task HmacSha1(string key, string value, string expected)
+        {
+            // Arrange
+            FluidValue input = value is null
+                ? NilValue.Empty
+                : new StringValue(value);
+            var arguments = new FilterArguments(FluidValue.Create(key, TemplateOptions.Default));
+            var context = new TemplateContext();
+
+            // Act
+            var result = await MiscFilters.HmacSha1(input, arguments, context);
+
+            // Assert
+            Assert.Equal(expected, result.ToStringValue());
+        }
+
+        [Theory]
+        [InlineData(null, "Fluid", "")]
+        [InlineData("secret_key", null, "")]
+        [InlineData("", "", "b613679a0814d9ec772f95d778c35fc5ff1697c493715653c6c712144292c5ad")]
+        [InlineData("", "Fluid", "e9f2db8bd3900c469e4b560227c5d53b48f644208a13de05bb400f7611d1a623")]
+        [InlineData("secret_key", "Fluid", "ac08ee5cdd007e1069680e93eb512049f5ff12afd0fe101de5c9b5043a047ea4")]
+        public async Task HmacSha256(string key, string value, string expected)
+        {
+            // Arrange
+            FluidValue input = value is null
+                ? NilValue.Empty
+                : new StringValue(value);
+            var arguments = new FilterArguments(FluidValue.Create(key, TemplateOptions.Default));
+            var context = new TemplateContext();
+
+            // Act
+            var result = await MiscFilters.HmacSha256(input, arguments, context);
+
+            // Assert
+            Assert.Equal(expected, result.ToStringValue());
+        }
+
         public static class TestObjects
         {
             public class Node

Fluid/Filters/MiscFilters.cs

@@ -1,8 +1,10 @@
+using Fluid.Utils;
 using Fluid.Values;
 using System.Buffers;
 using System.Globalization;
 using System.Net;
 using System.Reflection;
+using System.Security.Cryptography;
 using System.Text;
 using System.Text.Json;
 using TimeZoneConverter;
@@ -41,6 +43,8 @@ public static FilterCollection WithMiscFilters(this FilterCollection filters)
             filters.AddFilter("md5", MD5);
             filters.AddFilter("sha1", Sha1);
             filters.AddFilter("sha256", Sha256);
+            filters.AddFilter("hmac_sha1", HmacSha1);
+            filters.AddFilter("hmac_sha256", HmacSha256);
 
             return filters;
         }
@@ -933,5 +937,46 @@ public static ValueTask<FluidValue> Sha256(FluidValue input, FilterArguments arg
             return new StringValue(builder.ToString());
 #endif
         }
+
+        public static ValueTask<FluidValue> HmacSha1(FluidValue input, FilterArguments arguments, TemplateContext context) => ComputeHmac("HMACSHA1", input, arguments);
+
+        public static ValueTask<FluidValue> HmacSha256(FluidValue input, FilterArguments arguments, TemplateContext context) => ComputeHmac("HMACSHA256", input, arguments);
+
+        private static ValueTask<FluidValue> ComputeHmac(string algorithm, FluidValue input, FilterArguments arguments)
+        {
+            var key = arguments.At(0);
+            if (key.IsNil() || input.IsNil())
+            {
+                return StringValue.Empty;
+            }
+
+            var value = input.ToStringValue();
+            var keyBytes = Encoding.UTF8.GetBytes(key.ToStringValue());
+
+#if NET6_0_OR_GREATER
+#pragma warning disable CA5350
+            var hash = algorithm switch
+            {
+                "HMACSHA1" => HMACSHA1.HashData(keyBytes, Encoding.UTF8.GetBytes(value)),
+                "HMACSHA256" => HMACSHA256.HashData(keyBytes, Encoding.UTF8.GetBytes(value)),
+                _ => throw new ArgumentException("Unsupported HMAC algorithm", nameof(algorithm))
+            };
+#pragma warning restore CA5350
+
+            return new StringValue(HexUtilities.ToHexLower(hash));
+#else
+            using var provider = HMAC.Create(algorithm); 
+            provider.Key = keyBytes;
+            var builder = new StringBuilder(64);
+#pragma warning disable CA1850
+            foreach (var b in provider.ComputeHash(Encoding.UTF8.GetBytes(value)))
+#pragma warning restore CA1850
+            {
+                builder.Append(b.ToString("x2"));
+            }
+
+            return new StringValue(builder.ToString());
+#endif
+        }
     }
 }