Add support for Alipay certificate signing

src/AspNet.Security.OAuth.Alipay/AlipayAuthenticationConstants.cs

@@ -25,5 +25,18 @@ public static class Claims
         /// The user's gender. F: Female; M: Male.
         /// </summary>
         public const string Gender = "urn:alipay:gender";
+
+        /// <summary>
+        /// OpenID is the unique identifier for Alipay users at the application level.
+        /// See https://opendocs.alipay.com/mini/0ai2i6
+        /// </summary>
+        public const string OpenId = "urn:alipay:open_id";
+
+        /// <summary>
+        /// The internal identifier for Alipay users will no longer be independently available going forward and will be replaced by OpenID.
+        /// See https://opendocs.alipay.com/common/0ai736
+        /// </summary>
+        [Obsolete("The internal identifier for Alipay users will no longer be independently available going forward and will be replaced by OpenID. See https://opendocs.alipay.com/common/0ai736")]
+        public const string UserId = "urn:alipay:user_id";
     }
 }

src/AspNet.Security.OAuth.Alipay/AlipayAuthenticationHandler.cs

@@ -44,6 +44,21 @@ protected override Task<HandleRequestResult> HandleRemoteAuthenticateAsync()
         return base.HandleRemoteAuthenticateAsync();
     }
 
+    private const string SignType = "RSA2";
+
+    private async Task AddCertificateSignatureParametersAsync(SortedDictionary<string, string?> parameters)
+    {
+        ArgumentNullException.ThrowIfNull(Options.PublicKey);
+        ArgumentNullException.ThrowIfNull(Options.ApplicationCertificateSnKeyId);
+        ArgumentNullException.ThrowIfNull(Options.RootCertificateSnKeyId);
+
+        var appPublicKey = await Options.PublicKey(Options.ApplicationCertificateSnKeyId, Context.RequestAborted);
+        var alipayRootPublicKey = await Options.PublicKey(Options.RootCertificateSnKeyId, Context.RequestAborted);
+
+        parameters["app_cert_sn"] = AlipayCertificationUtil.GetCertSN(appPublicKey.Span);
+        parameters["alipay_root_cert_sn"] = AlipayCertificationUtil.GetRootCertSN(alipayRootPublicKey.Span, SignType);
+    }
+
     protected override async Task<OAuthTokenResponse> ExchangeCodeAsync([NotNull] OAuthCodeExchangeContext context)
     {
         // See https://opendocs.alipay.com/apis/api_9/alipay.system.oauth.token for details.
@@ -55,10 +70,16 @@ protected override async Task<OAuthTokenResponse> ExchangeCodeAsync([NotNull] OA
             ["format"] = "JSON",
             ["grant_type"] = "authorization_code",
             ["method"] = "alipay.system.oauth.token",
-            ["sign_type"] = "RSA2",
+            ["sign_type"] = SignType,
             ["timestamp"] = TimeProvider.GetUtcNow().ToString("yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture),
             ["version"] = "1.0",
         };
+
+        if (Options.UseCertificateSignatures)
+        {
+            await AddCertificateSignatureParametersAsync(tokenRequestParameters);
+        }
+
         tokenRequestParameters.Add("sign", GetRSA2Signature(tokenRequestParameters));
 
         // PKCE https://tools.ietf.org/html/rfc7636#section-4.5, see BuildChallengeUrl
@@ -103,10 +124,16 @@ protected override async Task<AuthenticationTicket> CreateTicketAsync(
             ["charset"] = "utf-8",
             ["format"] = "JSON",
             ["method"] = "alipay.user.info.share",
-            ["sign_type"] = "RSA2",
+            ["sign_type"] = SignType,
             ["timestamp"] = TimeProvider.GetUtcNow().ToString("yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture),
             ["version"] = "1.0",
         };
+
+        if (Options.UseCertificateSignatures)
+        {
+            await AddCertificateSignatureParametersAsync(parameters);
+        }
+
         parameters.Add("sign", GetRSA2Signature(parameters));
 
         var address = QueryHelpers.AddQueryString(Options.UserInformationEndpoint, parameters);

src/AspNet.Security.OAuth.Alipay/AlipayAuthenticationOptions.cs

@@ -29,5 +29,56 @@ public AlipayAuthenticationOptions()
         ClaimActions.MapJsonKey(Claims.Gender, "gender");
         ClaimActions.MapJsonKey(Claims.Nickname, "nick_name");
         ClaimActions.MapJsonKey(Claims.Province, "province");
+        ClaimActions.MapJsonKey(Claims.OpenId, "open_id");
+#pragma warning disable CS0618
+        ClaimActions.MapJsonKey(Claims.UserId, "user_id");
+#pragma warning restore CS0618
+    }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether to use certificate mode for signing calls.
+    /// <para>https://opendocs.alipay.com/common/057k53?pathHash=e18d6f77#%E8%AF%81%E4%B9%A6%E6%A8%A1%E5%BC%8F</para>
+    /// </summary>
+    public bool UseCertificateSignatures { get; set; }
+
+    /// <summary>
+    /// Gets or sets the optional ID for your Sign in with Application Public Key Certificate SN(app_cert_sn).
+    /// <para>https://opendocs.alipay.com/support/01raux</para>
+    /// </summary>
+    public string? ApplicationCertificateSnKeyId { get; set; }
+
+    /// <summary>
+    /// Gets or sets the optional ID for your Sign in with Alipay Root Certificate SN.
+    /// <para>https://opendocs.alipay.com/support/01rauy</para>
+    /// </summary>
+    public string? RootCertificateSnKeyId { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional delegate to get the client's public key which is passed
+    /// the value of the <see cref="ApplicationCertificateSnKeyId"/> or <see cref="RootCertificateSnKeyId"/> property and the <see cref="CancellationToken"/>
+    /// associated with the current HTTP request.
+    /// </summary>
+    /// <remarks>
+    /// The public key should be in PKCS #8 (<c>.p8</c>) format.
+    /// </remarks>
+    public Func<string, CancellationToken, Task<ReadOnlyMemory<char>>>? PublicKey { get; set; }
+
+    /// <inheritdoc />
+    public override void Validate()
+    {
+        base.Validate();
+
+        if (UseCertificateSignatures)
+        {
+            if (string.IsNullOrEmpty(ApplicationCertificateSnKeyId))
+            {
+                throw new ArgumentException($"The '{nameof(ApplicationCertificateSnKeyId)}' option must be provided if the '{nameof(UseCertificateSignatures)}' option is set to true.", nameof(ApplicationCertificateSnKeyId));
+            }
+
+            if (string.IsNullOrEmpty(RootCertificateSnKeyId))
+            {
+                throw new ArgumentException($"The '{nameof(RootCertificateSnKeyId)}' option must be provided if the '{nameof(UseCertificateSignatures)}' option is set to true.", nameof(RootCertificateSnKeyId));
+            }
+        }
     }
 }

src/AspNet.Security.OAuth.Alipay/AlipayAuthenticationOptionsExtensions.cs

@@ -0,0 +1,45 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
+ * See https://github.com/aspnet-contrib/AspNet.Security.OAuth.Providers
+ * for more information concerning the license and the contributors participating to this project.
+ */
+
+using AspNet.Security.OAuth.Alipay;
+using Microsoft.Extensions.FileProviders;
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+/// <summary>
+/// Extension methods to configure Sign in with Alipay authentication capabilities for an HTTP application pipeline.
+/// </summary>
+public static class AlipayAuthenticationOptionsExtensions
+{
+    /// <summary>
+    /// Configures the application to use a specified public key to generate a client secret for the provider when using certificate signatures.
+    /// </summary>
+    /// <param name="options">The Alipay authentication options to configure.</param>
+    /// <param name="publicKeyFile">
+    /// A delegate to a method to return the <see cref="IFileInfo"/> for the public
+    /// key which is passed the value of <see cref="AlipayAuthenticationOptions.ApplicationCertificateSnKeyId"/> or <see cref="AlipayAuthenticationOptions.RootCertificateSnKeyId"/>.
+    /// </param>
+    /// <returns>
+    /// The value of the <paramref name="options"/> argument.
+    /// </returns>
+    public static AlipayAuthenticationOptions UsePublicKey(
+        [NotNull] this AlipayAuthenticationOptions options,
+        [NotNull] Func<string, IFileInfo> publicKeyFile)
+    {
+        options.UseCertificateSignatures = true;
+        options.PublicKey = async (keyId, cancellationToken) =>
+        {
+            var fileInfo = publicKeyFile(keyId);
+
+            using var stream = fileInfo.CreateReadStream();
+            using var reader = new StreamReader(stream);
+
+            return (await reader.ReadToEndAsync(cancellationToken)).AsMemory();
+        };
+
+        return options;
+    }
+}

src/AspNet.Security.OAuth.Alipay/AlipayCertificationUtil.cs

@@ -0,0 +1,76 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
+ * See https://github.com/aspnet-contrib/AspNet.Security.OAuth.Providers
+ * for more information concerning the license and the contributors participating to this project.
+ */
+
+using System.Globalization;
+using System.Numerics;
+using System.Security.Cryptography;
+using System.Security.Cryptography.X509Certificates;
+using System.Text;
+
+namespace AspNet.Security.OAuth.Alipay;
+
+/// <summary>
+/// Based on https://github.com/alipay/alipay-sdk-net-all/blob/b482d75d322e740760f9230d2a3859090af642a7/v2/AlipaySDKNet.Standard/Util/AntCertificationUtil.cs.
+/// </summary>
+internal static class AlipayCertificationUtil
+{
+    public static string GetCertSN(ReadOnlySpan<char> certPem)
+    {
+        using var cert = X509Certificate2.CreateFromPem(certPem);
+        return GetCertSN(cert);
+    }
+
+    private static string GetCertSN(X509Certificate2 cert)
+    {
+        var issuerDN = cert.Issuer.Replace(", ", ",", StringComparison.Ordinal);
+        var serialNumber = new BigInteger(cert.GetSerialNumber()).ToString(CultureInfo.InvariantCulture);
+
+        if (issuerDN.StartsWith("CN", StringComparison.InvariantCulture))
+        {
+            return CalculateMd5(issuerDN + serialNumber);
+        }
+
+        var attributes = issuerDN.Split(',');
+        Array.Reverse(attributes);
+        return CalculateMd5(string.Join(',', attributes) + serialNumber);
+    }
+
+    public static string GetRootCertSN(ReadOnlySpan<char> certPem, string signType = "RSA2")
+    {
+        var certificates = new X509Certificate2Collection();
+        certificates.ImportFromPem(certPem);
+        var rootCertSN = string.Join('_', GetRootCertSN(certificates, signType));
+        return rootCertSN;
+    }
+
+    private static IEnumerable<string> GetRootCertSN(X509Certificate2Collection certificates, string signType)
+    {
+        foreach (X509Certificate2 cert in certificates)
+        {
+            var signatureAlgorithm = cert.SignatureAlgorithm.Value;
+            if (signatureAlgorithm != null)
+            {
+                if ((signType.StartsWith("RSA", StringComparison.OrdinalIgnoreCase) &&
+                    signatureAlgorithm.StartsWith("1.2.840.113549.1.1", StringComparison.OrdinalIgnoreCase)) ||
+                    (signType.StartsWith("SM2", StringComparison.OrdinalIgnoreCase) &&
+                    signatureAlgorithm.StartsWith("1.2.156.10197.1.501", StringComparison.OrdinalIgnoreCase)))
+                {
+                    yield return GetCertSN(cert);
+                }
+            }
+        }
+    }
+
+    private static string CalculateMd5(string s)
+    {
+        var buffer = Encoding.UTF8.GetBytes(s);
+        Span<byte> hash = stackalloc byte[MD5.HashSizeInBytes];
+#pragma warning disable CA5351
+        MD5.HashData(buffer, hash);
+#pragma warning restore CA5351
+        return Convert.ToHexStringLower(hash);
+    }
+}