前言

现在的系统后端开发的时候,会公开很多API接口
对于要登录认证后才能访问的接口,这样的请求验证就由身份认证模块完成
但是也有些接口是对外公开的,没有身份认证的接口
我们怎么保证接口的请求是合法的,有效的.
这样我们一般就是对请求的合法性做签名验证.

实现原理

为保证接口安全，每次请求必带以下header

| header名 | 类型 | 描述 |
| AppId | string | 应用Id |
| Ticks | string | 时间戳为1970年1月1日到现在时间的毫秒数（UTC时间） |
| RequestId | string | GUID字符串,作为请求唯一标志,防止重复请求 |
| Sign| string | 签名,签名算法如下 |

(资料图片仅供参考)

后端验证实现

验证AppId

model.AppId = context.Request.Headers["AppId"];        if (String.IsNullOrEmpty(model.AppId))        {            await this.ResponseValidFailedAsync(context, 501);            return;        }        var cacheSvc = context.RequestServices.GetRequiredService<IMemoryCache>();        var cacheAppIdKey = #34;RequestValidSign:APPID:{model.AppId}";        var curConfig = cacheSvc.GetOrCreate<AppConfigModel>(cacheAppIdKey, (e) =>        {            e.SlidingExpiration = TimeSpan.FromHours(1);            var configuration = context.RequestServices.GetRequiredService<IConfiguration>();            var listAppConfig = configuration.GetSection(AppConfigModel.ConfigSectionKey).Get<AppConfigModel[]>();            return listAppConfig.SingleOrDefault(x => x.AppId == model.AppId);        });        if (curConfig == null)        {            await this.ResponseValidFailedAsync(context, 502);            return;        }

验证时间戳

var ticksString = context.Request.Headers["Ticks"].ToString();            if (String.IsNullOrEmpty(ticksString))            {                await this.ResponseValidFailedAsync(context, 503);                return;            }            model.Ticks = long.Parse(context.Request.Headers["Ticks"].ToString());            var diffTime = DateTime.UtcNow - (new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddMilliseconds(model.Ticks));            var expirTime = TimeSpan.FromSeconds(300);//过期时间            if (diffTime > expirTime)            {                await this.ResponseValidFailedAsync(context, 504);                return;            }

验证请求ID

model.RequestId = context.Request.Headers["RequestId"];            if (String.IsNullOrEmpty(model.RequestId))            {                await this.ResponseValidFailedAsync(context, 505);                return;            }            var cacheKey = #34;RequestValidSign:RequestId:{model.AppId}:{model.RequestId}";            if (cacheSvc.TryGetValue(cacheKey, out _))            {                await this.ResponseValidFailedAsync(context, 506);                return;            }            else                cacheSvc.Set(cacheKey, model.RequestId, expirTime);

验证签名

1.验证签名是否正常
2.签名字符串是#34;{AppId}{Ticks}{RequestId}{AppSecret}"组成
3.然后把签名字符串做MD5，再与请求传过来的Sign签名对比
4.如果一至就表示正常请求，请求通过。如果不一至，返回失败

public bool Valid()    {        var validStr = #34;{AppId}{Ticks}{RequestId}{AppSecret}";        return validStr.ToMD5String() == Sign;    }            model.Sign = context.Request.Headers["Sign"];            if (!model.Valid())            {                await this.ResponseValidFailedAsync(context, 507);                return;            }

源代码

我们把所有代码写成一个Asp.Net Core的中间件

/// <summary>/// 请求签名验证/// </summary>public class RequestValidSignMiddleware{    private readonly RequestDelegate _next;    public RequestValidSignMiddleware(RequestDelegate next)    {        _next = next;    }    public async Task InvokeAsync(HttpContext context)    {        var model = new RequestValidSignModel();        //1.先验证AppId是不是有,没有就直接返回失败        //2.如果有的话,就去缓存里取AppID对应的配置(如果缓存里没有,就去配置文件里取)        //3.如果没有对应AppId的配置,说明不是正确的请求,返回失败        model.AppId = context.Request.Headers["AppId"];        if (String.IsNullOrEmpty(model.AppId))        {            await this.ResponseValidFailedAsync(context, 501);            return;        }        var cacheSvc = context.RequestServices.GetRequiredService<IMemoryCache>();        var cacheAppIdKey = #34;RequestValidSign:APPID:{model.AppId}";        var curConfig = cacheSvc.GetOrCreate<AppConfigModel>(cacheAppIdKey, (e) =>        {            e.SlidingExpiration = TimeSpan.FromHours(1);            var configuration = context.RequestServices.GetRequiredService<IConfiguration>();            var listAppConfig = configuration.GetSection(AppConfigModel.ConfigSectionKey).Get<AppConfigModel[]>();            return listAppConfig.SingleOrDefault(x => x.AppId == model.AppId);        });        if (curConfig == null)        {            await this.ResponseValidFailedAsync(context, 502);            return;        }        //1.把缓存/配置里面的APP配置取出来,拿到AppSecret        //2.如果请求里附带了AppSecret(调试用),那么就只验证AppSecret是否正确        //3.传过来的AppSecret必需是Base64编码后的        //4.然后比对传过来的AppSecret是否与配置的AppSecret一至,如果一至就通过,不一至就返回失败        //5.如果请求里没有附带AppSecret,那么走其它验证逻辑.        model.AppSecret = curConfig.AppSecret;        var headerSecret = context.Request.Headers["AppSecret"].ToString();        if (!String.IsNullOrEmpty(headerSecret))        {            var secretBuffer = new byte[1024];            var secretIsBase64 = Convert.TryFromBase64String(headerSecret, new Span<byte>(secretBuffer), out var bytesWritten);            if (secretIsBase64 && Encoding.UTF8.GetString(secretBuffer, 0, bytesWritten) == curConfig.AppSecret)                await _next(context);            else            {                await this.ResponseValidFailedAsync(context, 508);                return;            }        }        else        {            //1.验证时间戳是不是有在请求头里传过来，没有就返回失败            //2.验证时间戳与当前时间比较，如果不在过期时间(5分钟)之内的请求，就返回失败            //时间戳为1970年1月1日到现在时间的毫秒数（UTC时间）            var ticksString = context.Request.Headers["Ticks"].ToString();            if (String.IsNullOrEmpty(ticksString))            {                await this.ResponseValidFailedAsync(context, 503);                return;            }            model.Ticks = long.Parse(context.Request.Headers["Ticks"].ToString());            var diffTime = DateTime.UtcNow - (new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddMilliseconds(model.Ticks));            var expirTime = TimeSpan.FromSeconds(300);//过期时间            if (diffTime > expirTime)            {                await this.ResponseValidFailedAsync(context, 504);                return;            }            //1.验证请求ID是不是有在请求头里传过来，没有就返回失败            //2.验证请求ID是不是已经在缓存里存在，如果存在就表示重复请求，那么就返回失败            //3.如果请求ID在缓存中不存在，那么就表示正常的请求，同时把请求ID添加到缓存            model.RequestId = context.Request.Headers["RequestId"];            if (String.IsNullOrEmpty(model.RequestId))            {                await this.ResponseValidFailedAsync(context, 505);                return;            }            var cacheKey = #34;RequestValidSign:RequestId:{model.AppId}:{model.RequestId}";            if (cacheSvc.TryGetValue(cacheKey, out _))            {                await this.ResponseValidFailedAsync(context, 506);                return;            }            else                cacheSvc.Set(cacheKey, model.RequestId, expirTime);            //1.验证签名是否正常            //2.签名字符串是#34;{AppId}{Ticks}{RequestId}{AppSecret}"组成            //3.然后把签名字符串做MD5，再与请求传过来的Sign签名对比            //4.如果一至就表示正常请求，请求通过。如果不一至，返回失败            model.Sign = context.Request.Headers["Sign"];            if (!model.Valid())            {                await this.ResponseValidFailedAsync(context, 507);                return;            }            await _next(context);        }    }    /// <summary>    /// 返回验证失败    /// </summary>    /// <param name="context"></param>    /// <param name="status"></param>    /// <returns></returns>    public async Task ResponseValidFailedAsync(HttpContext context, int status)    {        context.Response.StatusCode = 500;        await context.Response.WriteAsJsonAsync(new ComResult() { Success = false, Status = status, Msg = "请求签名验证失败" }, Extention.DefaultJsonSerializerOptions, context.RequestAborted);    }}public class AppConfigModel{    public const string ConfigSectionKey = "AppConfig";    /// <summary>    /// 应用Id    /// </summary>    public string AppId { get; set; }    /// <summary>    /// 应用密钥    /// </summary>    public string AppSecret { get; set; }}public class RequestValidSignModel : AppConfigModel{    /// <summary>    /// 前端时间戳    /// Date.now()    /// 1970 年 1 月 1 日 00:00:00 (UTC) 到当前时间的毫秒数    /// </summary>    public long Ticks { get; set; }    /// <summary>    /// 请求ID    /// </summary>    public string RequestId { get; set; }    /// <summary>    /// 签名    /// </summary>    public string Sign { get; set; }    public bool Valid()    {        var validStr = #34;{AppId}{Ticks}{RequestId}{AppSecret}";        return validStr.ToMD5String() == Sign;    }}

中间件注册扩展

写一个中间件的扩展,这样我们在Program里可以方便的使用/停用中间件

/// <summary>/// 中间件注册扩展/// </summary>public static class RequestValidSignMiddlewareExtensions{    public static IApplicationBuilder UseRequestValidSign(this IApplicationBuilder builder)    {        return builder.UseMiddleware<RequestValidSignMiddleware>();    }}///Program.csapp.UseRequestValidSign();

与Swagger结合

我们一般对外提供在线的Swagger文档
如果我们增加了请求验证的Header,那么所有接口文档里面都要把验证的Header添加到在线文档里面

/// <summary>/// 请求签名验证添加Swagger请求头/// </summary>public class RequestValidSignSwaggerOperationFilter : IOperationFilter{    public void Apply(OpenApiOperation operation, OperationFilterContext context)    {        if (operation.Parameters == null)            operation.Parameters = new List<OpenApiParameter>();        operation.Parameters.Add(new OpenApiParameter        {            Name = "AppId",            In = ParameterLocation.Header,            Required = true,            Description = "应用ID",            Schema = new OpenApiSchema            {                Type = "string"            }        });        operation.Parameters.Add(new OpenApiParameter        {            Name = "Ticks",            In = ParameterLocation.Header,            Required = true,            Description = "时间戳",            Example = new OpenApiString(((long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds).ToString()),            Schema = new OpenApiSchema            {                Type = "string"            }        });        operation.Parameters.Add(new OpenApiParameter        {            Name = "RequestId",            In = ParameterLocation.Header,            Required = true,            Description = "请求ID",            Example = new OpenApiString(Guid.NewGuid().ToString()),            Schema = new OpenApiSchema            {                Type = "string"            }        });        operation.Parameters.Add(new OpenApiParameter        {            Name = "Sign",            In = ParameterLocation.Header,            Required = true,            Description = "请求签名",            //{AppId}{Ticks}{RequestId}{AppSecret}            Example = new OpenApiString("MD5({AppId}{Ticks}{RequestId}{AppSecret})"),            Schema = new OpenApiSchema            {                Type = "string"            }        });        operation.Parameters.Add(new OpenApiParameter        {            Name = "AppSecret",            In = ParameterLocation.Header,            Description = "应用密钥(调试用)",            Example = new OpenApiString("BASE64({AppSecret})"),            Schema = new OpenApiSchema            {                Type = "string"            }        });    }}///在Program.cs里添加Swagger请求验证Headerbuilder.Services.AddSwaggerGen(c =>{    c.OperationFilter<RequestValidSignSwaggerOperationFilter>();});

客户端调用实现

我们如果用HttpClient调用的话,就要在调用请求前
设置后请求头,AppId,Ticks,RequestId,Sign

public async Task<string> GetIPAsync(CancellationToken token)        {            this.SetSignHeader();            var result = await Client.GetStringAsync("/Get", token);            return result;        }        public void SetSignHeader()        {            this.Client.DefaultRequestHeaders.Clear();            var ticks = ((long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds).ToString();            var requestId = Guid.NewGuid().ToString();            var signString = #34;{this.Config.AppId}{ticks}{requestId}{this.Config.AppSecret}";            var sign = this.GetMD5(signString);            this.Client.DefaultRequestHeaders.Add("AppId", this.Config.AppId);            this.Client.DefaultRequestHeaders.Add("Ticks", ticks);            this.Client.DefaultRequestHeaders.Add("RequestId", requestId);            this.Client.DefaultRequestHeaders.Add("Sign", sign);        }        public string GetMD5(string value)        {            using (MD5 md5 = MD5.Create())            {                byte[] inputBytes = Encoding.UTF8.GetBytes(value);                byte[] hashBytes = md5.ComputeHash(inputBytes);                StringBuilder sb = new StringBuilder();                for (int i = 0; i < hashBytes.Length; i++)                {                    sb.Append(hashBytes[i].ToString("x2"));                }                return sb.ToString();            }        }

最终效果

当我们没有传签名参数的时候,返回失败

当我们把签名参数都传正确后,返回正确

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