✨ 添加C#实现的API签名工具，包括核心库、命令行工具和使用文档，支持多种签名算法和环境变量配置。

csharp/README.md

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+# API签名工具 - C#实现
+
+本目录包含API签名机制的C#语言实现，提供了签名计算与验证的完整功能。
+
+## 功能特点
+
+- 支持多种签名算法（MD5, SHA1, SHA256, HMAC-SHA256）
+- 支持自定义签名参数名称
+- 支持URL参数签名
+- 内置防重放攻击机制（时间戳+nonce）
+- 跨平台（.NET Standard 2.0 兼容）
+- 提供命令行工具进行测试
+- 无外部依赖，仅使用.NET标准库
+
+## 项目结构
+
+根据实际项目文件结构：
+
+```plaintext
+csharp/
+├── src/
+│   ├── ApiSigner/
+│   │   ├── ApiSigner.cs           # 签名工具实现
+│   │   ├── ApiSigner.csproj       # 项目文件
+│   │   ├── SignatureAlgorithm.cs  # 签名算法定义
+│   │   ├── SignOptions.cs         # 签名配置
+│   │   └── SignVerifyResult.cs    # 验证结果类型
+│   │
+│   ├── ApiSigner.Cli/
+│   │   ├── ApiSigner.Cli.csproj   # 命令行项目文件
+│   │   └── Program.cs             # 命令行入口
+│   │
+│   └── ApiSigner.sln              # 解决方案文件
+```
+
+## 使用方法
+
+### 构建项目
+
+```bash
+dotnet build src/ApiSigner.sln
+```
+
+### 运行命令行工具
+
+```bash
+dotnet run --project src/ApiSigner.Cli/ApiSigner.Cli.csproj [选项]
+```
+
+### 命令行选项
+
+| 选项 | 描述 |
+|------|------|
+| `-a, --algorithm` | 签名算法: MD5, SHA1, SHA256, HMAC-SHA256 |
+| `-u, --url` | API基础URL |
+| `-p, --param` | 请求参数，格式为key=value，可多次使用 |
+| `-k, --key` | 访问密钥ID |
+| `-s, --secret` | 密钥 |
+| `-c, --channel` | 合作渠道方ID |
+| `-h, --help` | 显示帮助信息 |
+
+### 常用命令示例
+
+**基本用法**
+
+```bash
+dotnet run --project src/ApiSigner.Cli/ApiSigner.Cli.csproj
+```
+
+**自定义参数**
+
+```bash
+dotnet run --project src/ApiSigner.Cli/ApiSigner.Cli.csproj \
+  -u "https://api.example.com/user/info" \
+  -p "userId=12345" -p "action=getInfo" \
+  -k "YOUR_ACCESS_KEY" \
+  -s "YOUR_SECRET_KEY" \
+  -c "3"
+```
+
+**指定签名算法**
+
+```bash
+dotnet run --project src/ApiSigner.Cli/ApiSigner.Cli.csproj -a SHA256
+```
+
+**帮助信息**
+
+```bash
+dotnet run --project src/ApiSigner.Cli/ApiSigner.Cli.csproj --help
+```
+
+### API接口测试实例
+
+使用真实API接口进行测试：
+
+```bash
+# 未签名的API调用测试 - 返回错误
+curl "https://api-v1.sound-force.com:8443/p/album/single/media-url?channelId=3&singleId=381980"
+# 返回: {"code":400,"data":null,"msg":"Missing AccessKeyId","success":false}
+
+# 生成访问https://api-v1.sound-force.com:8443/p/album/single/media-url的签名URL
+dotnet run --project src/ApiSigner.Cli/ApiSigner.Cli.csproj \
+  -a MD5 \
+  -u "https://api-v1.sound-force.com:8443/p/album/single/media-url" \
+  -p "singleId=381980" \
+  -k "YOUR_ACCESS_KEY" \
+  -s "YOUR_SECRET_KEY" \
+  -c "3"
+
+# 使用curl测试API接口
+signedUrl=$(dotnet run --project src/ApiSigner.Cli/ApiSigner.Cli.csproj \
+  -a MD5 \
+  -u "https://api-v1.sound-force.com:8443/p/album/single/media-url" \
+  -p "singleId=381980" \
+  -k "YOUR_ACCESS_KEY" \
+  -s "YOUR_SECRET_KEY" \
+  -c "3" | grep -A 1 "签名后的URL:" | tail -n 1)
+curl -v "$signedUrl"
+```
+
+请注意：
+
+- 替换`YOUR_ACCESS_KEY`为实际的访问密钥ID
+- 替换`YOUR_SECRET_KEY`为实际的密钥
+- 示例使用的渠道ID为`3`，请根据实际情况调整
+
+使用有效的密钥和签名后，API接口将返回成功响应(状态码200)并提供媒体URL数据。
+
+### 代码集成
+
+```csharp
+using SoundForce.ApiSigner;
+
+// 创建签名选项
+var options = new SignOptions { Algorithm = SignatureAlgorithm.Md5 };
+
+// 创建签名工具
+var signer = new ApiSigner(options);
+
+// 准备请求参数
+var parameters = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+{
+    ["singleId"] = "381980"
+};
+
+// 执行签名
+var signedParams = signer.SignRequest(
+    parameters, 
+    "YOUR_ACCESS_KEY", 
+    "YOUR_SECRET_KEY", 
+    "3"
+);
+
+// 或签名URL
+var signedUrl = signer.SignUrl(
+    "https://api-v1.sound-force.com:8443/p/album/single/media-url",
+    parameters,
+    "YOUR_ACCESS_KEY", 
+    "YOUR_SECRET_KEY", 
+    "3"
+);
+```
+
+### 环境变量
+
+该工具支持从`.env`文件加载以下配置：
+
+- `ACCESS_KEY_ID`: 访问密钥ID
+- `SECRET_KEY`: 密钥
+- `CHANNEL_ID`: 渠道ID
+- `SIGN_ALGORITHM`: 签名算法
+- `API_BASE_URL`: API基础URL
+
+## 注意事项
+
+1. 在生产环境中，应该妥善保管SecretKey，不要硬编码在代码中
+2. 服务端需要自行实现nonce存储与验证以防止重放攻击
+3. 时间戳验证需要考虑服务器与客户端之间可能存在的时间差
+4. 默认情况下，命令行工具从`.env`文件或环境变量读取配置

csharp/src/ApiSigner.Cli/ApiSigner.Cli.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>SoundForce.ApiSigner.Cli</RootNamespace>
+    <AssemblyName>SoundForce.ApiSigner.Cli</AssemblyName>
+    <LangVersion>8.0</LangVersion>
+    <Nullable>enable</Nullable>
+    <Authors>Sound Force</Authors>
+    <Description>API签名工具命令行接口</Description>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="DotNetEnv" Version="3.1.1" />
+    <PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\ApiSigner\ApiSigner.csproj" />
+  </ItemGroup>
+
+</Project> 

csharp/src/ApiSigner.Cli/Program.cs

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+using System;
+using System.Collections.Generic;
+using System.CommandLine;
+using System.Threading.Tasks;
+
+namespace SoundForce.ApiSigner.Cli
+{
+    class Program
+    {
+        static async Task<int> Main(string[] args)
+        {
+            var rootCommand = new RootCommand("API签名工具");
+
+            var algorithmOption = new Option<string>(
+                aliases: new[] { "--algorithm", "-a" },
+                description: "签名算法: MD5, SHA1, SHA256, HMAC-SHA256",
+                getDefaultValue: () => Environment.GetEnvironmentVariable("SIGN_ALGORITHM") ?? "MD5");
+
+            var urlOption = new Option<string>(
+                aliases: new[] { "--url", "-u" },
+                description: "基础URL地址",
+                getDefaultValue: () =>
+                    Environment.GetEnvironmentVariable("API_BASE_URL") ?? "https://api.example.com/v1/data");
+
+            var paramOption = new Option<string[]>(
+                aliases: new[] { "--param", "-p" },
+                description: "请求参数，格式为key=value，可多次指定")
+            {
+                AllowMultipleArgumentsPerToken = true
+            };
+
+            var accessKeyIdOption = new Option<string>(
+                aliases: new[] { "--key", "-k" },
+                description: "访问密钥ID",
+                getDefaultValue: () => Environment.GetEnvironmentVariable("ACCESS_KEY_ID") ?? "test-access-key-id");
+
+            var secretKeyOption = new Option<string>(
+                aliases: new[] { "--secret", "-s" },
+                description: "密钥",
+                getDefaultValue: () => Environment.GetEnvironmentVariable("SECRET_KEY") ?? "test-secret-key");
+
+            var channelIdOption = new Option<string>(
+                aliases: new[] { "--channel", "-c" },
+                description: "合作渠道方ID",
+                getDefaultValue: () => Environment.GetEnvironmentVariable("CHANNEL_ID") ?? "test-channel-id");
+
+            rootCommand.AddOption(algorithmOption);
+            rootCommand.AddOption(urlOption);
+            rootCommand.AddOption(paramOption);
+            rootCommand.AddOption(accessKeyIdOption);
+            rootCommand.AddOption(secretKeyOption);
+            rootCommand.AddOption(channelIdOption);
+
+            rootCommand.SetHandler((algorithmStr, url, paramArr, accessKeyId, secretKey, channelId) =>
+                {
+                    SignatureAlgorithm algorithm = SignatureAlgorithm.Md5;
+                    if (Enum.TryParse(algorithmStr, true, out SignatureAlgorithm parsedAlgorithm))
+                    {
+                        algorithm = parsedAlgorithm;
+                    }
+                    else
+                    {
+                        Console.WriteLine($"警告: 无效的签名算法: {algorithmStr}，使用默认MD5算法");
+                    }
+
+                    var options = new SignOptions
+                    {
+                        Algorithm = algorithm,
+                        SignatureName = "sign" // 使用"sign"而不是"signature"
+                    };
+
+                    var signer = new ApiSigner(options);
+
+                    var parameters = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+                    if (paramArr.Length > 0)
+                    {
+                        foreach (var param in paramArr)
+                        {
+                            var parts = param.Split('=', 2);
+                            if (parts.Length == 2)
+                            {
+                                parameters[parts[0]] = parts[1];
+                            }
+                        }
+                    }
+                    else
+                    {
+                        parameters["userId"] = "12345";
+                        parameters["action"] = "getData";
+                        parameters["data"] = "测试数据";
+                    }
+
+                    Console.WriteLine("===================== API签名示例 =====================");
+                    Console.WriteLine($"AccessKeyId: {accessKeyId}");
+                    Console.WriteLine($"ChannelId: {channelId}");
+                    Console.WriteLine($"SecretKey: {secretKey}");
+                    Console.WriteLine($"签名算法: {algorithm}");
+                    Console.WriteLine($"基础URL: {url}");
+                    Console.WriteLine("请求参数:");
+                    foreach (var param in parameters)
+                    {
+                        Console.WriteLine($"  {param.Key}: {param.Value}");
+                    }
+
+                    var signedUrl = signer.SignUrl(url, parameters, accessKeyId, secretKey, channelId);
+                    Console.WriteLine("\n签名后的URL:");
+                    Console.WriteLine(signedUrl);
+
+                    var signedParams = signer.SignRequest(parameters, accessKeyId, secretKey, channelId);
+                    Console.WriteLine("\n签名后的参数:");
+                    foreach (var param in signedParams)
+                    {
+                        Console.WriteLine($"  {param.Key}: {param.Value}");
+                    }
+
+                    DemonstrateAlgorithms(parameters, accessKeyId, secretKey, channelId);
+                },
+                algorithmOption, urlOption, paramOption, accessKeyIdOption, secretKeyOption, channelIdOption);
+
+            return await rootCommand.InvokeAsync(args);
+        }
+
+        /// <summary>
+        /// 演示不同算法的签名结果
+        /// </summary>
+        private static void DemonstrateAlgorithms(
+            Dictionary<string, string> parameters,
+            string accessKeyId,
+            string secretKey,
+            string channelId)
+        {
+            Console.WriteLine("\n不同算法的签名结果:");
+
+            var algorithms = new[]
+            {
+                SignatureAlgorithm.Md5,
+                SignatureAlgorithm.Sha1,
+                SignatureAlgorithm.Sha256,
+                SignatureAlgorithm.HmacSha256
+            };
+
+            foreach (var alg in algorithms)
+            {
+                var options = new SignOptions { Algorithm = alg };
+                var signer = new ApiSigner(options);
+
+                // 添加必要的参数用于签名
+                var signParams = new Dictionary<string, string>(parameters)
+                {
+                    ["AccessKeyId"] = accessKeyId,
+                    ["channelId"] = channelId
+                };
+
+                var signature = signer.CalculateSignature(signParams, secretKey);
+                Console.WriteLine($"  {alg}: {signature}");
+            }
+        }
+    }
+}

csharp/src/ApiSigner.sln

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+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.33627.172
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ApiSigner", "ApiSigner\ApiSigner.csproj", "{6DD01F88-4A7B-40EC-B3D0-48F4D394B237}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ApiSigner.Cli", "ApiSigner.Cli\ApiSigner.Cli.csproj", "{D74C4FB8-5723-4C94-8D2C-9FB26716872E}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{6DD01F88-4A7B-40EC-B3D0-48F4D394B237}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{6DD01F88-4A7B-40EC-B3D0-48F4D394B237}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{6DD01F88-4A7B-40EC-B3D0-48F4D394B237}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{6DD01F88-4A7B-40EC-B3D0-48F4D394B237}.Release|Any CPU.Build.0 = Release|Any CPU
+		{D74C4FB8-5723-4C94-8D2C-9FB26716872E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D74C4FB8-5723-4C94-8D2C-9FB26716872E}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D74C4FB8-5723-4C94-8D2C-9FB26716872E}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D74C4FB8-5723-4C94-8D2C-9FB26716872E}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {6F7E3A89-97D4-4D4F-ACFF-A12F36CFCB3E}
+	EndGlobalSection
+EndGlobal 

csharp/src/ApiSigner/ApiSigner.cs

@@ -0,0 +1,312 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Web;
+
+namespace SoundForce.ApiSigner
+{
+    /// <summary>
+    /// API签名工具
+    /// </summary>
+    public class ApiSigner
+    {
+        private readonly SignOptions _options;
+        private static readonly Regex AlphaNumericPattern = new Regex("^[a-zA-Z0-9]*$", RegexOptions.Compiled);
+
+        /// <summary>
+        /// 创建API签名工具
+        /// </summary>
+        /// <param name="options">签名选项，如为null则使用默认选项</param>
+        public ApiSigner(SignOptions? options = null)
+        {
+            _options = options ?? new SignOptions();
+        }
+
+        /// <summary>
+        /// 生成随机字符串
+        /// </summary>
+        /// <returns>一个基于当前时间的随机字符串</returns>
+        public string GenerateNonce()
+        {
+            return string.Concat(DateTimeOffset.UtcNow.ToUnixTimeMilliseconds().ToString(),
+                Guid.NewGuid().ToString("N").AsSpan(0, 8));
+        }
+
+        /// <summary>
+        /// 获取当前时间戳（毫秒）
+        /// </summary>
+        /// <returns>当前的Unix时间戳（毫秒）</returns>
+        public long GetTimestamp()
+        {
+            return DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+        }
+
+        /// <summary>
+        /// 对请求进行签名
+        /// </summary>
+        /// <param name="parameters">请求参数</param>
+        /// <param name="accessKeyId">访问密钥ID</param>
+        /// <param name="secretKey">密钥</param>
+        /// <param name="channelId">合作渠道方ID</param>
+        /// <returns>添加了签名的完整参数</returns>
+        public Dictionary<string, string> SignRequest(
+            IDictionary<string, string> parameters,
+            string accessKeyId,
+            string secretKey,
+            string channelId)
+        {
+            // 创建用于签名的参数副本
+            var signParams = new Dictionary<string, string>(parameters);
+
+            // 添加认证参数
+            var timestamp = GetTimestamp();
+            signParams[_options.KeyName] = accessKeyId;
+            signParams[_options.ChannelIdName] = channelId;
+            signParams[_options.TimestampName] = timestamp.ToString();
+            signParams[_options.NonceName] = GenerateNonce();
+
+            // 计算签名
+            var signature = CalculateSignature(signParams, secretKey);
+
+            // 添加签名到参数
+            signParams[_options.SignatureName] = signature;
+
+            return signParams;
+        }
+
+        /// <summary>
+        /// 对URL进行签名
+        /// </summary>
+        /// <param name="baseUrl">基础URL地址</param>
+        /// <param name="parameters">请求参数</param>
+        /// <param name="accessKeyId">访问密钥ID</param>
+        /// <param name="secretKey">密钥</param>
+        /// <param name="channelId">合作渠道方ID</param>
+        /// <returns>添加了签名的完整URL</returns>
+        public string SignUrl(
+            string baseUrl,
+            IDictionary<string, string> parameters,
+            string accessKeyId,
+            string secretKey,
+            string channelId)
+        {
+            // 对请求签名
+            var signedParams = SignRequest(parameters, accessKeyId, secretKey, channelId);
+
+            // 构建URL查询字符串
+            var queryString = BuildQueryString(signedParams);
+
+            // 处理已有参数的URL
+            return baseUrl.Contains('?') ? $"{baseUrl}&{queryString}" : $"{baseUrl}?{queryString}";
+        }
+
+        /// <summary>
+        /// 构建URL查询字符串
+        /// </summary>
+        /// <param name="parameters">参数</param>
+        /// <returns>查询字符串</returns>
+        private string BuildQueryString(IDictionary<string, string> parameters)
+        {
+            // 按键排序
+            var sortedParams = parameters.OrderBy(p => p.Key);
+
+            // 构建查询字符串
+            var queryParts =
+                sortedParams.Select(p => $"{HttpUtility.UrlEncode(p.Key)}={HttpUtility.UrlEncode(p.Value)}");
+            return string.Join("&", queryParts);
+        }
+
+        /// <summary>
+        /// 计算签名
+        /// </summary>
+        /// <param name="parameters">请求参数</param>
+        /// <param name="secretKey">密钥</param>
+        /// <returns>签名字符串</returns>
+        public string CalculateSignature(IDictionary<string, string> parameters, string secretKey)
+        {
+            // 按键名排序并生成规范化的请求字符串
+            var signingString = CreateSigningString(parameters);
+
+            // 添加密钥
+            signingString = $"{signingString}&key={secretKey}";
+
+            // 使用指定算法计算签名
+            return _options.Algorithm switch
+            {
+                SignatureAlgorithm.Md5 => CalculateMd5(signingString),
+                SignatureAlgorithm.Sha1 => CalculateSha1(signingString),
+                SignatureAlgorithm.Sha256 => CalculateSha256(signingString),
+                SignatureAlgorithm.HmacSha256 => CalculateHmacSha256(signingString, secretKey),
+                _ => CalculateMd5(signingString)
+            };
+        }
+
+        /// <summary>
+        /// 创建用于签名的规范化字符串
+        /// </summary>
+        /// <param name="parameters">请求参数</param>
+        /// <returns>按键名排序并拼接的字符串</returns>
+        public string CreateSigningString(IDictionary<string, string> parameters)
+        {
+            // 排除签名参数
+            var filteredParams = parameters
+                .Where(p => p.Key != _options.SignatureName)
+                .OrderBy(p => p.Key)
+                .Select(p =>
+                {
+                    var value = p.Value;
+                    // 仅对非字母数字字符进行URL编码
+                    if (NeedsUrlEncode(value))
+                    {
+                        value = HttpUtility.UrlEncode(value);
+                    }
+
+                    return $"{p.Key}={value}";
+                });
+
+            return string.Join("&", filteredParams);
+        }
+
+        /// <summary>
+        /// 判断是否需要对字符串进行URL编码
+        /// </summary>
+        /// <param name="value">需要判断的字符串</param>
+        /// <returns>如果包含非字母数字字符，返回true，否则返回false</returns>
+        private bool NeedsUrlEncode(string value)
+        {
+            return !AlphaNumericPattern.IsMatch(value);
+        }
+
+        /// <summary>
+        /// 验证签名
+        /// </summary>
+        /// <param name="parameters">所有请求参数，包括签名</param>
+        /// <param name="secretKey">密钥</param>
+        /// <param name="maxAgeMs">允许的最大时间差（毫秒）</param>
+        /// <returns>验证结果</returns>
+        public SignVerifyResult VerifySignature(IDictionary<string, string> parameters, string secretKey,
+            long maxAgeMs = 300000)
+        {
+            // 获取并验证必要参数
+            if (!parameters.TryGetValue(_options.KeyName, out _))
+            {
+                return SignVerifyResult.Failure($"缺少参数: {_options.KeyName}");
+            }
+
+            if (!parameters.TryGetValue(_options.ChannelIdName, out _))
+            {
+                return SignVerifyResult.Failure($"缺少参数: {_options.ChannelIdName}");
+            }
+
+            if (!parameters.TryGetValue(_options.TimestampName, out var timestampStr))
+            {
+                return SignVerifyResult.Failure($"缺少参数: {_options.TimestampName}");
+            }
+
+            // 验证时间戳
+            if (!long.TryParse(timestampStr, out var timestamp))
+            {
+                return SignVerifyResult.Failure("无效的时间戳");
+            }
+
+            var now = GetTimestamp();
+            if (Math.Abs(now - timestamp) > maxAgeMs)
+            {
+                return SignVerifyResult.Failure("时间戳过期");
+            }
+
+            if (!parameters.TryGetValue(_options.NonceName, out _))
+            {
+                return SignVerifyResult.Failure($"缺少参数: {_options.NonceName}");
+            }
+
+            // 这里可以插入nonce验证逻辑，防止重放攻击
+            // 服务端需要维护一个时效性的nonce存储
+
+            if (!parameters.TryGetValue(_options.SignatureName, out var providedSignature))
+            {
+                return SignVerifyResult.Failure($"缺少参数: {_options.SignatureName}");
+            }
+
+            // 计算签名并比较
+            var expectedSignature = CalculateSignature(parameters, secretKey);
+
+            return string.Equals(expectedSignature, providedSignature, StringComparison.OrdinalIgnoreCase)
+                ? SignVerifyResult.Success()
+                : SignVerifyResult.Failure("签名不匹配");
+        }
+
+        #region 签名算法实现
+
+        /// <summary>
+        /// 计算MD5签名
+        /// </summary>
+        /// <param name="content">内容</param>
+        /// <returns>MD5签名</returns>
+        private string CalculateMd5(string content)
+        {
+            var inputBytes = Encoding.UTF8.GetBytes(content);
+            var hashBytes = MD5.HashData(inputBytes);
+            return BytesToHex(hashBytes);
+        }
+
+        /// <summary>
+        /// 计算SHA1签名
+        /// </summary>
+        /// <param name="content">内容</param>
+        /// <returns>SHA1签名</returns>
+        private string CalculateSha1(string content)
+        {
+            var inputBytes = Encoding.UTF8.GetBytes(content);
+            var hashBytes = SHA1.HashData(inputBytes);
+            return BytesToHex(hashBytes);
+        }
+
+        /// <summary>
+        /// 计算SHA256签名
+        /// </summary>
+        /// <param name="content">内容</param>
+        /// <returns>SHA256签名</returns>
+        private string CalculateSha256(string content)
+        {
+            var inputBytes = Encoding.UTF8.GetBytes(content);
+            var hashBytes = SHA256.HashData(inputBytes);
+            return BytesToHex(hashBytes);
+        }
+
+        /// <summary>
+        /// 计算HMAC-SHA256签名
+        /// </summary>
+        /// <param name="content">内容</param>
+        /// <param name="key">密钥</param>
+        /// <returns>HMAC-SHA256签名</returns>
+        private string CalculateHmacSha256(string content, string key)
+        {
+            using var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key));
+            var inputBytes = Encoding.UTF8.GetBytes(content);
+            var hashBytes = hmac.ComputeHash(inputBytes);
+            return BytesToHex(hashBytes);
+        }
+
+        /// <summary>
+        /// 将字节数组转换为十六进制字符串
+        /// </summary>
+        /// <param name="bytes">字节数组</param>
+        /// <returns>十六进制字符串</returns>
+        private string BytesToHex(byte[] bytes)
+        {
+            var builder = new StringBuilder(bytes.Length * 2);
+            foreach (var b in bytes)
+            {
+                builder.Append(b.ToString("x2"));
+            }
+
+            return builder.ToString();
+        }
+
+        #endregion
+    }
+}

csharp/src/ApiSigner/ApiSigner.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>SoundForce.ApiSigner</RootNamespace>
+    <AssemblyName>SoundForce.ApiSigner</AssemblyName>
+    <LangVersion>8.0</LangVersion>
+    <Nullable>enable</Nullable>
+    <Authors>Sound Force</Authors>
+    <Description>API签名计算与验证工具</Description>
+  </PropertyGroup>
+
+</Project> 

csharp/src/ApiSigner/SignOptions.cs

@@ -0,0 +1,55 @@
+namespace SoundForce.ApiSigner
+{
+    /// <summary>
+    /// 签名选项
+    /// </summary>
+    public class SignOptions
+    {
+        /// <summary>
+        /// 签名算法
+        /// </summary>
+        public SignatureAlgorithm Algorithm { get; set; } = SignatureAlgorithm.Md5;
+
+        /// <summary>
+        /// AccessKeyId参数名
+        /// </summary>
+        public string KeyName { get; set; } = "AccessKeyId";
+
+        /// <summary>
+        /// 合作渠道方ID参数名
+        /// </summary>
+        public string ChannelIdName { get; set; } = "channelId";
+
+        /// <summary>
+        /// 时间戳参数名
+        /// </summary>
+        public string TimestampName { get; set; } = "timestamp";
+
+        /// <summary>
+        /// 随机字符串参数名
+        /// </summary>
+        public string NonceName { get; set; } = "nonce";
+
+        /// <summary>
+        /// 签名参数名 (注意：这里使用sign而不是signature)
+        /// </summary>
+        public string SignatureName { get; set; } = "sign";
+
+        /// <summary>
+        /// 创建默认签名选项的新实例
+        /// </summary>
+        public SignOptions()
+        {
+        }
+
+        /// <summary>
+        /// 返回表示当前对象的字符串
+        /// </summary>
+        /// <returns>表示当前对象的字符串</returns>
+        public override string ToString()
+        {
+            return
+                $"SignOptions{{Algorithm={Algorithm}, KeyName='{KeyName}', ChannelIdName='{ChannelIdName}', TimestampName='{TimestampName}', NonceName='{NonceName}', SignatureName='{SignatureName}'}}";
+        }
+    }
+}

csharp/src/ApiSigner/SignVerifyResult.cs

@@ -0,0 +1,42 @@
+namespace SoundForce.ApiSigner
+{
+    /// <summary>
+    /// 签名验证结果
+    /// </summary>
+    public class SignVerifyResult
+    {
+        /// <summary>
+        /// 签名是否有效
+        /// </summary>
+        public bool IsValid { get; }
+
+        /// <summary>
+        /// 错误信息，如果没有错误则为null
+        /// </summary>
+        public string? Error { get; }
+
+        /// <summary>
+        /// 创建表示成功的验证结果
+        /// </summary>
+        /// <returns>成功的验证结果</returns>
+        public static SignVerifyResult Success() => new SignVerifyResult(true, null);
+
+        /// <summary>
+        /// 创建表示失败的验证结果
+        /// </summary>
+        /// <param name="error">错误信息</param>
+        /// <returns>失败的验证结果</returns>
+        public static SignVerifyResult Failure(string error) => new SignVerifyResult(false, error);
+
+        /// <summary>
+        /// 创建验证结果
+        /// </summary>
+        /// <param name="isValid">签名是否有效</param>
+        /// <param name="error">错误信息</param>
+        private SignVerifyResult(bool isValid, string? error)
+        {
+            IsValid = isValid;
+            Error = error;
+        }
+    }
+}

csharp/src/ApiSigner/SignatureAlgorithm.cs

@@ -0,0 +1,76 @@
+using System;
+
+namespace SoundForce.ApiSigner
+{
+    /// <summary>
+    /// 签名算法类型
+    /// </summary>
+    public enum SignatureAlgorithm
+    {
+        /// <summary>
+        /// MD5算法（默认、最快）
+        /// </summary>
+        Md5,
+
+        /// <summary>
+        /// SHA1算法
+        /// </summary>
+        Sha1,
+
+        /// <summary>
+        /// SHA256算法
+        /// </summary>
+        Sha256,
+
+        /// <summary>
+        /// HMAC-SHA256算法（最安全）
+        /// </summary>
+        HmacSha256
+    }
+
+    /// <summary>
+    /// 签名算法扩展方法
+    /// </summary>
+    public static class SignatureAlgorithmExtensions
+    {
+        /// <summary>
+        /// 从字符串解析算法类型
+        /// </summary>
+        /// <param name="algorithm">算法字符串</param>
+        /// <returns>签名算法枚举</returns>
+        /// <exception cref="ArgumentException">如果算法无效</exception>
+        public static SignatureAlgorithm FromString(string? algorithm)
+        {
+            if (string.IsNullOrEmpty(algorithm))
+                return SignatureAlgorithm.Md5;
+
+            return algorithm.ToUpperInvariant() switch
+            {
+                "MD5" => SignatureAlgorithm.Md5,
+                "SHA1" => SignatureAlgorithm.Sha1,
+                "SHA256" => SignatureAlgorithm.Sha256,
+                "HMAC_SHA256" => SignatureAlgorithm.HmacSha256,
+                "HMACSHA256" => SignatureAlgorithm.HmacSha256,
+                "HMAC-SHA256" => SignatureAlgorithm.HmacSha256,
+                _ => throw new ArgumentException($"无效的签名算法: {algorithm}", nameof(algorithm))
+            };
+        }
+
+        /// <summary>
+        /// 获取算法的字符串表示
+        /// </summary>
+        /// <param name="algorithm">签名算法</param>
+        /// <returns>算法的字符串表示</returns>
+        public static string ToString(this SignatureAlgorithm algorithm)
+        {
+            return algorithm switch
+            {
+                SignatureAlgorithm.Md5 => "MD5",
+                SignatureAlgorithm.Sha1 => "SHA1",
+                SignatureAlgorithm.Sha256 => "SHA256",
+                SignatureAlgorithm.HmacSha256 => "HMAC-SHA256",
+                _ => "UNKNOWN"
+            };
+        }
+    }
+}