small fixes

Author: tinohager

src/Nager.EmailAuthentication.UnitTest/DkimSignatureTests/Parser/FoldingTest.cs

@@ -13,7 +13,7 @@ public sealed class FoldingTest
         [TestMethod]
         public void TryParse_ValidSelector_ReturnsTrueAndPopulatesDataFragment()
         {
-            var dkimSignatureRaw = "v=1; a=rsa-sha256; c=relaxed/relaxed; d=\tdmarc.com; h=cc:content-transfer-encoding:content-type\t:content-type:date:date:from:from:in-reply-to:message-id\t:mime-version:reply-to:sender:subject:subject:to:to; s=selector1; t=\t1691032934; x=1691119334; bh=R3apwsNJ82/QU5M387ntjAXd9fEanDDMRVC\tWFXcJ4BU=; b=ERPju20CMzamO4CElotsxcged+Ospob+sROWU3fdwUXfA2edzbe\ttfb1QaOG5TM+qh4D5MwArT0VQTw7B/J2jvfTpgXTu/+8Lg8SOArRFyHTRQXfUDul\tY872sMKYLuO9n3I9ewthEZNen3m2YLVPQ5RyGkoBFSj1jh7m8crBgnFRBaztgOXc\tbNhI2OTdJckxlBoHQfggPEgwaoT1oJt0T8GQuUTqkEq/yD8K1CZ2hriBryRpw/tC\tBiDU/EK4fPEHKVzwRs+K3g6vPJ0tdz9zG5KyMnDtHmWfHymTXfJjnxhJ5DO5j/Nu\tng67Nt+cn+Jpmeko8eWd96TQzqokrW9PsoA==";
+            var dkimSignatureRaw = "v=1; a=rsa-sha256; c=relaxed/relaxed; d=\r\n\tdmarc.com; h=cc:content-transfer-encoding:content-type\r\n\t:content-type:date:date:from:from:in-reply-to:message-id\r\n\t:mime-version:reply-to:sender:subject:subject:to:to; s=selector1; t=\r\n\t1691032934; x=1691119334; bh=R3apwsNJ82/QU5M387ntjAXd9fEanDDMRVC\r\n\tWFXcJ4BU=; b=ERPju20CMzamO4CElotsxcged+Ospob+sROWU3fdwUXfA2edzbe\r\n\ttfb1QaOG5TM+qh4D5MwArT0VQTw7B/J2jvfTpgXTu/+8Lg8SOArRFyHTRQXfUDul\r\n\tY872sMKYLuO9n3I9ewthEZNen3m2YLVPQ5RyGkoBFSj1jh7m8crBgnFRBaztgOXc\r\n\tbNhI2OTdJckxlBoHQfggPEgwaoT1oJt0T8GQuUTqkEq/yD8K1CZ2hriBryRpw/tC\r\n\tBiDU/EK4fPEHKVzwRs+K3g6vPJ0tdz9zG5KyMnDtHmWfHymTXfJjnxhJ5DO5j/Nu\r\n\tng67Nt+cn+Jpmeko8eWd96TQzqokrW9PsoA==";
 
             var isSuccessful = DkimSignatureParser.TryParse(dkimSignatureRaw, out var dkimSignature, out var parsingResults);
 

src/Nager.EmailAuthentication/DkimSignatureParser.cs

@@ -172,8 +172,8 @@ public static bool TryParseV1(
             dkimSignature = new DkimSignatureV1
             {
                 Version = dkimSignatureDataFragment.Version,
-                SigningDomainIdentifier = dkimSignatureDataFragment.SigningDomainIdentifier.Trim(' ', '\t'),
-                Selector = dkimSignatureDataFragment.Selector.Trim(' ', '\t'),
+                SigningDomainIdentifier = dkimSignatureDataFragment.SigningDomainIdentifier,
+                Selector = dkimSignatureDataFragment.Selector,
                 BodyHash = dkimSignatureDataFragment.BodyHash,
                 BodyLengthCount = bodyLengthCount,
                 QueryMethods = dkimSignatureDataFragment.QueryMethods,

src/Nager.EmailAuthentication/FragmentParsers/DkimSignatureDataFragmentParserV1.cs

@@ -520,6 +520,7 @@ private static ParsingResult[] ValidateSignedHeaderFields(ValidateRequest valida
 
             var parts = validateRequest.Value.Split(':');
 
+            //https://datatracker.ietf.org/doc/html/rfc6376 -> Attacks Involving Extra Header Fields
             //https://security.stackexchange.com/questions/265408/how-many-times-need-e-mail-headers-be-signed-with-dkim-to-mitigate-dkim-header-i#:~:text=If%20the%20e%2Dmail%20uses,field%20of%20the%20DKIM%20signature.
             var groupedHeaders = parts.GroupBy(o => o).Select(g => new { Key = g.Key.ToLower(), Count = g.Count() });
             foreach (var groupedHeader in groupedHeaders)