starting working on activity

src/BirdsiteLive.Domain/UserService.cs

@@ -1,24 +1,33 @@
 using System;
+using System.Collections.Generic;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading.Tasks;
 using BirdsiteLive.ActivityPub;
 using BirdsiteLive.Common.Settings;
+using BirdsiteLive.Cryptography;
 using BirdsiteLive.Twitter.Models;
+using Tweetinvi.Core.Exceptions;
 
 namespace BirdsiteLive.Domain
 {
     public interface IUserService
     {
         Actor GetUser(TwitterUser twitterUser);
+        Task<bool> FollowRequestedAsync(string signature, string method, string path, string queryString, Dictionary<string, string> requestHeaders, ActivityFollow activity);
     }
 
     public class UserService : IUserService
     {
         private readonly ICryptoService _cryptoService;
+        private readonly IActivityPubService _activityPubService;
         private readonly string _host;
 
         #region Ctor
-        public UserService(InstanceSettings instanceSettings, ICryptoService cryptoService)
+        public UserService(InstanceSettings instanceSettings, ICryptoService cryptoService, IActivityPubService activityPubService)
         {
             _cryptoService = cryptoService;
+            _activityPubService = activityPubService;
             _host = $"https://{instanceSettings.Domain.Replace("https://",string.Empty).Replace("http://", string.Empty).TrimEnd('/')}";
         }
         #endregion
@@ -53,5 +62,78 @@ namespace BirdsiteLive.Domain
             };
             return user;
         }
+
+        public async Task<bool> FollowRequestedAsync(string signature, string method, string path, string queryString, Dictionary<string, string>  requestHeaders, ActivityFollow activity)
+        {
+            // Validate
+            if (!await ValidateSignature(activity.actor, signature, method, path, queryString, requestHeaders)) return false;
+
+            // Save Follow in DB
+
+            // Send Accept Activity 
+
+            
+            throw new NotImplementedException();
+        }
+
+        private async Task<bool> ValidateSignature(string actor, string rawSig, string method, string path, string queryString, Dictionary<string, string> requestHeaders)
+        {
+            var signatures = rawSig.Split(',');
+            var signature_header = new Dictionary<string, string>();
+            foreach (var signature in signatures)
+            {
+                var splitSig = signature.Replace("\"", string.Empty).Split('=');
+                signature_header.Add(splitSig[0], splitSig[1]);
+            }
+
+            signature_header["signature"] = signature_header["signature"] + "==";
+
+            var key_id = signature_header["keyId"];
+            var headers = signature_header["headers"];
+            var algorithm = signature_header["algorithm"];
+            var sig = Convert.FromBase64String(signature_header["signature"]);
+
+
+            var remoteUser = await _activityPubService.GetUser(actor);
+
+            var toDecode = remoteUser.publicKey.publicKeyPem.Trim().Remove(0, remoteUser.publicKey.publicKeyPem.IndexOf('\n'));
+            toDecode = toDecode.Remove(toDecode.LastIndexOf('\n')).Replace("\n", "");
+            var signKey = ASN1.ToRSA(Convert.FromBase64String(toDecode));
+
+            var toSign = new StringBuilder();
+            //var comparisonString = headers.Split(' ').Select(signed_header_name =>
+            //{
+            //    if (signed_header_name == "(request-target)")
+            //        return "(request-target): post /inbox";
+            //    else
+            //        return $"{signed_header_name}: {r.Headers[signed_header_name.ToUpperInvariant()]}";
+            //});
+
+            foreach (var headerKey in headers.Split(' '))
+            {
+                if (headerKey == "(request-target)") toSign.Append($"(request-target): {method.ToLower()} {path}{queryString}\n");
+                else toSign.Append($"{headerKey}: {string.Join(", ", requestHeaders[headerKey])}\n");
+            }
+            toSign.Remove(toSign.Length - 1, 1);
+
+            //var signKey = ASN1.ToRSA(Convert.FromBase64String(toDecode));
+
+            //new RSACryptoServiceProvider(keyId.publicKey.publicKeyPem);
+
+            //Create a new instance of RSACryptoServiceProvider.
+            RSACryptoServiceProvider key = new RSACryptoServiceProvider();
+
+            //Get an instance of RSAParameters from ExportParameters function.
+            RSAParameters RSAKeyInfo = key.ExportParameters(false);
+
+            //Set RSAKeyInfo to the public key values.
+            RSAKeyInfo.Modulus = Convert.FromBase64String(toDecode);
+
+            key.ImportParameters(RSAKeyInfo);
+
+            var result = signKey.VerifyData(Encoding.UTF8.GetBytes(toSign.ToString()), sig, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
+
+            return result;
+        }
     }
 }