Generics migration complete

49 files changed, 228 insertions, 357 deletions

diff --git a/crypto/test/src/asn1/test/AttributeTableUnitTest.cs b/crypto/test/src/asn1/test/AttributeTableUnitTest.cs
index c6d69fa2b..d5f49f0a8 100644
--- a/crypto/test/src/asn1/test/AttributeTableUnitTest.cs
+++ b/crypto/test/src/asn1/test/AttributeTableUnitTest.cs
@@ -1,9 +1,7 @@
 using System;
-using System.Collections;
 
 using NUnit.Framework;
 
-using Org.BouncyCastle.Asn1;
 using Asn1Cms = Org.BouncyCastle.Asn1.Cms;
 using Org.BouncyCastle.Utilities.Test;
 
diff --git a/crypto/test/src/asn1/test/X509NameTest.cs b/crypto/test/src/asn1/test/X509NameTest.cs
index c344042a2..bafec3226 100644
--- a/crypto/test/src/asn1/test/X509NameTest.cs
+++ b/crypto/test/src/asn1/test/X509NameTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 
 using NUnit.Framework;
diff --git a/crypto/test/src/cmp/test/ProtectedMessageTest.cs b/crypto/test/src/cmp/test/ProtectedMessageTest.cs
index 98bae77ee..4c242d48a 100644
--- a/crypto/test/src/cmp/test/ProtectedMessageTest.cs
+++ b/crypto/test/src/cmp/test/ProtectedMessageTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 
 using NUnit.Framework;
@@ -324,7 +323,7 @@ namespace Org.BouncyCastle.Cmp.Tests
     {
         IDictionary<DerObjectIdentifier, string> attrs = new Dictionary<DerObjectIdentifier, string>();
         IList<DerObjectIdentifier> ord = new List<DerObjectIdentifier>();
-        IList values = new ArrayList();
+        IList<string> values = new List<string>();
 
         private DateTime notBefore, notAfter;
         private AsymmetricKeyParameter publicKey;
diff --git a/crypto/test/src/cms/test/CMSTestUtil.cs b/crypto/test/src/cms/test/CMSTestUtil.cs
index b6818bb8a..016260625 100644
--- a/crypto/test/src/cms/test/CMSTestUtil.cs
+++ b/crypto/test/src/cms/test/CMSTestUtil.cs
@@ -213,7 +213,7 @@ namespace Org.BouncyCastle.Cms.Tests
 				{
 					buf.Append(Encoding.ASCII.GetString(data, i, data.Length - i));
 				}
-				buf.Append('\n');
+				buf.AppendLine();
 			}
 
 			return buf.ToString();
diff --git a/crypto/test/src/crmf/test/CrmfTest.cs b/crypto/test/src/crmf/test/CrmfTest.cs
index 7a5349db1..f900e0879 100644
--- a/crypto/test/src/crmf/test/CrmfTest.cs
+++ b/crypto/test/src/crmf/test/CrmfTest.cs
@@ -1,10 +1,7 @@
 using System;
-using System.Collections;
 
 using NUnit.Framework;
 
-using Org.BouncyCastle.Asn1;
-using Org.BouncyCastle.Asn1.Cms;
 using Org.BouncyCastle.Asn1.Crmf;
 using Org.BouncyCastle.Asn1.Nist;
 using Org.BouncyCastle.Asn1.Pkcs;
@@ -156,7 +153,7 @@ namespace Org.BouncyCastle.Crmf.Tests
             IsTrue(archiveControl.EnvelopedData);
             RecipientInformationStore recips = archiveControl.GetEnvelopedData().GetRecipientInfos();
 
-            IList collection =  (IList)recips.GetRecipients();
+            var collection = recips.GetRecipients();
 
             IsTrue(collection.Count == 1);
             KeyTransRecipientInformation info = (KeyTransRecipientInformation)collection[0];
diff --git a/crypto/test/src/crypto/prng/test/DrbgTestVector.cs b/crypto/test/src/crypto/prng/test/DrbgTestVector.cs
index b3f17e458..ca64dfa5b 100644
--- a/crypto/test/src/crypto/prng/test/DrbgTestVector.cs
+++ b/crypto/test/src/crypto/prng/test/DrbgTestVector.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 
 using Org.BouncyCastle.Utilities.Encoders;
 
@@ -16,7 +16,7 @@ namespace Org.BouncyCastle.Crypto.Prng.Test
         private string _personalisation;
         private int _ss;
         private string[] _ev;
-        private IList _ai = new ArrayList();
+        private IList<string> _ai = new List<string>();
 
         public DrbgTestVector(IDigest digest, IEntropySource eSource, bool predictionResistance, string nonce,
             int securityStrength, string[] expected)
diff --git a/crypto/test/src/crypto/test/GOST3411_2012_256DigestTest.cs b/crypto/test/src/crypto/test/GOST3411_2012_256DigestTest.cs
index 4b48eab4f..3f3e04f7a 100644
--- a/crypto/test/src/crypto/test/GOST3411_2012_256DigestTest.cs
+++ b/crypto/test/src/crypto/test/GOST3411_2012_256DigestTest.cs
@@ -1,13 +1,10 @@
 using System;
-using System.Collections;
 
 using NUnit.Framework;
 
-using Org.BouncyCastle.Crypto;
 using Org.BouncyCastle.Crypto.Digests;
 using Org.BouncyCastle.Crypto.Macs;
 using Org.BouncyCastle.Crypto.Parameters;
-using Org.BouncyCastle.Crypto.Tests;
 using Org.BouncyCastle.Utilities;
 using Org.BouncyCastle.Utilities.Encoders;
 
diff --git a/crypto/test/src/crypto/test/GOST3411_2012_512DigestTest.cs b/crypto/test/src/crypto/test/GOST3411_2012_512DigestTest.cs
index 7b4c0273a..bad1742ef 100644
--- a/crypto/test/src/crypto/test/GOST3411_2012_512DigestTest.cs
+++ b/crypto/test/src/crypto/test/GOST3411_2012_512DigestTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 
 using NUnit.Framework;
 
diff --git a/crypto/test/src/crypto/test/NistEccTest.cs b/crypto/test/src/crypto/test/NistEccTest.cs
index aaf4f666b..4269ef55d 100644
--- a/crypto/test/src/crypto/test/NistEccTest.cs
+++ b/crypto/test/src/crypto/test/NistEccTest.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.IO;
 using System.Text.RegularExpressions;
 
@@ -33,9 +33,9 @@ namespace Org.BouncyCastle.Crypto.Tests
             }
         }
 
-        public IEnumerable CollectTestVectors()
+        public IEnumerable<object[]> CollectTestVectors()
         {
-            ArrayList testVectors = new ArrayList();
+            var testVectors = new List<object[]>();
             string curve = null;
             BigInteger k = null;
             BigInteger x = null;
@@ -72,7 +72,7 @@ namespace Org.BouncyCastle.Crypto.Tests
 
                     if (null != curve && null != k && null != x && null != y)
                     {
-                        testVectors.Add(new object[] {curve, k, x, y});
+                        testVectors.Add(new object[]{curve, k, x, y});
                         k = null;
                         x = null;
                         y = null;
diff --git a/crypto/test/src/crypto/test/cavp/CavpReader.cs b/crypto/test/src/crypto/test/cavp/CavpReader.cs
index dc32e0ff8..cbdaca155 100644
--- a/crypto/test/src/crypto/test/cavp/CavpReader.cs
+++ b/crypto/test/src/crypto/test/cavp/CavpReader.cs
@@ -1,31 +1,23 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.IO;
 
-using Org.BouncyCastle.Crypto.Digests;
-using Org.BouncyCastle.Crypto.Engines;
-using Org.BouncyCastle.Crypto.Macs;
 using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities.Collections;
 using Org.BouncyCastle.Utilities.Encoders;
 using Org.BouncyCastle.Utilities.Test;
 
 namespace Org.BouncyCastle.Crypto.Tests.Cavp
 {
-    internal class Vector : Hashtable
+    internal class Vector : Dictionary<string, object>
     {
-        private Hashtable mHeader = null;
+        private IDictionary<string, string> mHeader = null;
 
-        public Vector(Hashtable header)
+        public Vector(IDictionary<string, string> header)
         {
             this.mHeader = header;
         }
 
-        public Hashtable Header
-        {
-            get { return mHeader; }
-            set { this.mHeader = value; }
-        }
-
         public string ValueAsString(string name)
         {
             return this[name] as string;
@@ -33,7 +25,7 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
 
         public string HeaderAsString(string name)
         {
-            return Header[name] as string;
+            return CollectionUtilities.GetValueOrNull(mHeader, name);
         }
 
         public byte[] ValueAsBytes(string name)
@@ -49,13 +41,8 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
 
         public byte[] HeaderAsBytes(string name)
         {
-            string value = Header[name] as string;
-            if (value != null)
-            {
-                return Hex.Decode(value);
-            }
-
-            return null;
+            string value = HeaderAsString(name);
+            return value == null ? null : Hex.Decode(value);
         }
 
         public int ValueAsInt(string name)
@@ -79,10 +66,10 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
 
     internal class CavpReader
     {
-        public static ArrayList ReadVectorFile(string name)
+        public static IList<Vector> ReadVectorFile(string name)
         {
-            ArrayList vectors = new ArrayList();
-            Hashtable header = null;
+            var vectors = new List<Vector>();
+            IDictionary<string, string> header = null;
             Vector currentVector = null;
 
             int headerState = 0;
@@ -148,7 +135,7 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
                     //
                     if (headerState == 0 && line.StartsWith("[") && line.EndsWith("]"))
                     {
-                        header = new Hashtable();
+                        header = new Dictionary<string, string>();
                         headerState = 1;
                     }
 
diff --git a/crypto/test/src/crypto/test/cavp/KDFCounterTests.cs b/crypto/test/src/crypto/test/cavp/KDFCounterTests.cs
index 4cd20a93b..bce4c9516 100644
--- a/crypto/test/src/crypto/test/cavp/KDFCounterTests.cs
+++ b/crypto/test/src/crypto/test/cavp/KDFCounterTests.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 
 using NUnit.Framework;
 
@@ -26,11 +26,11 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
         public override void PerformTest()
         {
             string file = "KDFCTR_gen.rsp";
-            ArrayList vectors = CavpReader.ReadVectorFile(file);
+            var vectors = CavpReader.ReadVectorFile(file);
             ProcessVectors(file, vectors);
         }
 
-        private void ProcessVectors(string name, ArrayList vectors)
+        private void ProcessVectors(string name, IList<Vector> vectors)
         {
             foreach (Vector vector in vectors)
             {
diff --git a/crypto/test/src/crypto/test/cavp/KDFDoublePipelineTests.cs b/crypto/test/src/crypto/test/cavp/KDFDoublePipelineTests.cs
index 7d1558ce9..a995db884 100644
--- a/crypto/test/src/crypto/test/cavp/KDFDoublePipelineTests.cs
+++ b/crypto/test/src/crypto/test/cavp/KDFDoublePipelineTests.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 
 using NUnit.Framework;
 
@@ -28,7 +27,7 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
         private void KdfDblPipelineNoCounterTest()
         {
             string file = "KDFDblPipelineNoCounter_gen.rsp";
-            ArrayList vectors = CavpReader.ReadVectorFile(file);
+            var vectors = CavpReader.ReadVectorFile(file);
 
             foreach (Vector vector in vectors)
             {
@@ -53,7 +52,7 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
         private void KdfDblPipelineCounterTest()
         {
             string file = "KDFDblPipelineCounter_gen.rsp";
-            ArrayList vectors = CavpReader.ReadVectorFile(file);
+            var vectors = CavpReader.ReadVectorFile(file);
 
             foreach (Vector vector in vectors)
             {
diff --git a/crypto/test/src/crypto/test/cavp/KDFFeedbackCounterTests.cs b/crypto/test/src/crypto/test/cavp/KDFFeedbackCounterTests.cs
index 26789bf28..e734c99f0 100644
--- a/crypto/test/src/crypto/test/cavp/KDFFeedbackCounterTests.cs
+++ b/crypto/test/src/crypto/test/cavp/KDFFeedbackCounterTests.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 
 using NUnit.Framework;
 
@@ -28,7 +27,7 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
         private void KdfFeedbackNoCounterTest()
         {
             string file = "KDFFeedbackNoCounter_gen.rsp";
-            ArrayList vectors = CavpReader.ReadVectorFile(file);
+            var vectors = CavpReader.ReadVectorFile(file);
 
             foreach (Vector vector in vectors)
             {
@@ -54,7 +53,7 @@ namespace Org.BouncyCastle.Crypto.Tests.Cavp
         private void KdfFeedbackCounterTest()
         {
             string file = "KDFFeedbackCounter_gen.rsp";
-            ArrayList vectors = CavpReader.ReadVectorFile(file);
+            var vectors = CavpReader.ReadVectorFile(file);
 
             foreach (Vector vector in vectors)
             {
diff --git a/crypto/test/src/math/ec/test/ECAlgorithmsTest.cs b/crypto/test/src/math/ec/test/ECAlgorithmsTest.cs
index dbbd0a328..419b022a7 100644
--- a/crypto/test/src/math/ec/test/ECAlgorithmsTest.cs
+++ b/crypto/test/src/math/ec/test/ECAlgorithmsTest.cs
@@ -1,12 +1,11 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 
 using NUnit.Framework;
 
 using Org.BouncyCastle.Asn1.X9;
 using Org.BouncyCastle.Crypto.EC;
 using Org.BouncyCastle.Security;
-using Org.BouncyCastle.Utilities.Collections;
 
 namespace Org.BouncyCastle.Math.EC.Tests
 {
@@ -128,12 +127,12 @@ namespace Org.BouncyCastle.Math.EC.Tests
             return new BigInteger(x9.N.BitLength, Random);
         }
 
-        private IList GetTestCurves()
+        private IList<X9ECParameters> GetTestCurves()
         {
-            ArrayList x9s = new ArrayList();
-            ISet names = new HashSet(ECNamedCurveTable.Names);
-            names.AddAll(CustomNamedCurves.Names);
+            var names = new HashSet<string>(ECNamedCurveTable.Names);
+            names.UnionWith(CustomNamedCurves.Names);
 
+            var x9s = new List<X9ECParameters>();
             foreach (string name in names)
             {
                 X9ECParameters x9 = ECNamedCurveTable.GetByName(name);
@@ -151,7 +150,7 @@ namespace Org.BouncyCastle.Math.EC.Tests
             return x9s;
         }
 
-        private void AddTestCurves(IList x9s, X9ECParameters x9)
+        private void AddTestCurves(IList<X9ECParameters> x9s, X9ECParameters x9)
         {
             ECCurve curve = x9.Curve;
 
diff --git a/crypto/test/src/math/ec/test/ECPointPerformanceTest.cs b/crypto/test/src/math/ec/test/ECPointPerformanceTest.cs
index 059416427..18051226b 100644
--- a/crypto/test/src/math/ec/test/ECPointPerformanceTest.cs
+++ b/crypto/test/src/math/ec/test/ECPointPerformanceTest.cs
@@ -179,7 +179,7 @@ namespace Org.BouncyCastle.Math.EC.Tests
 
             names.Sort();
 
-            ISet oids = new HashSet();
+            var oids = new HashSet<DerObjectIdentifier>();
             foreach (string name in names)
             {
                 DerObjectIdentifier oid = ECNamedCurveTable.GetOid(name);
diff --git a/crypto/test/src/math/ec/test/ECPointTest.cs b/crypto/test/src/math/ec/test/ECPointTest.cs
index 4e3fc5832..7a833a413 100644
--- a/crypto/test/src/math/ec/test/ECPointTest.cs
+++ b/crypto/test/src/math/ec/test/ECPointTest.cs
@@ -7,7 +7,6 @@ using Org.BouncyCastle.Asn1.X9;
 using Org.BouncyCastle.Crypto.EC;
 using Org.BouncyCastle.Security;
 using Org.BouncyCastle.Utilities;
-using Org.BouncyCastle.Utilities.Collections;
 using Org.BouncyCastle.Utilities.Encoders;
 
 namespace Org.BouncyCastle.Math.EC.Tests
@@ -538,7 +537,7 @@ namespace Org.BouncyCastle.Math.EC.Tests
             names.AddRange(ECNamedCurveTable.Names);
             names.AddRange(CustomNamedCurves.Names);
 
-            ISet uniqNames = new HashSet(names);
+            var uniqNames = new HashSet<string>(names);
 
             foreach (string name in uniqNames)
             {
diff --git a/crypto/test/src/math/ec/test/FixedPointTest.cs b/crypto/test/src/math/ec/test/FixedPointTest.cs
index 433f956da..bc90bdfc3 100644
--- a/crypto/test/src/math/ec/test/FixedPointTest.cs
+++ b/crypto/test/src/math/ec/test/FixedPointTest.cs
@@ -27,7 +27,7 @@ namespace Org.BouncyCastle.Math.EC.Tests
             names.AddRange(ECNamedCurveTable.Names);
             names.AddRange(CustomNamedCurves.Names);
 
-            ISet uniqNames = new HashSet(names);
+            var uniqNames = new HashSet<string>(names);
 
             foreach (string name in uniqNames)
             {
diff --git a/crypto/test/src/openpgp/test/IgnoreMarkerPacketInCertificatesTest.cs b/crypto/test/src/openpgp/test/IgnoreMarkerPacketInCertificatesTest.cs
index 7b845d077..71196edae 100644
--- a/crypto/test/src/openpgp/test/IgnoreMarkerPacketInCertificatesTest.cs
+++ b/crypto/test/src/openpgp/test/IgnoreMarkerPacketInCertificatesTest.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.IO;
 using System.Text;
 
@@ -71,12 +71,12 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
 
             PgpPublicKeyRing certificate = (PgpPublicKeyRing)objectFactory.NextPgpObject();
             IsEquals("Bob Babbage <bob@openpgp.example>", First(certificate.GetPublicKey().GetUserIds()));
-            IEnumerable publicKeys = certificate.GetPublicKeys();
-            IEnumerator publicKeyEnum = publicKeys.GetEnumerator();
+            var publicKeys = certificate.GetPublicKeys();
+            var publicKeyEnum = publicKeys.GetEnumerator();
             IsTrue(publicKeyEnum.MoveNext());
             PgpPublicKey primaryKey = (PgpPublicKey)publicKeyEnum.Current;
             IsEquals(new BigInteger("FBFCC82A015E7330", 16).LongValue, primaryKey.KeyId);
-            IEnumerable signatures = primaryKey.GetSignatures();
+            var signatures = primaryKey.GetSignatures();
             IsEquals(1, Count(signatures));
 
             IsTrue(publicKeyEnum.MoveNext());
@@ -94,19 +94,19 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
 			Assert.AreEqual(Name + ": Okay", resultText);
 		}
 
-        private int Count(IEnumerable e)
+        private int Count<T>(IEnumerable<T> e)
         {
             int count = 0;
-            foreach (object o in e)
+            foreach (T t in e)
             {
                 ++count;
             }
             return count;
         }
 
-        private object First(IEnumerable e)
+        private T First<T>(IEnumerable<T> e)
         {
-            IEnumerator enumerator = e.GetEnumerator();
+            var enumerator = e.GetEnumerator();
             IsTrue(enumerator.MoveNext());
             return enumerator.Current;
         }
diff --git a/crypto/test/src/openpgp/test/PGPClearSignedSignatureTest.cs b/crypto/test/src/openpgp/test/PGPClearSignedSignatureTest.cs
index 98762fab1..a6f03c06f 100644
--- a/crypto/test/src/openpgp/test/PGPClearSignedSignatureTest.cs
+++ b/crypto/test/src/openpgp/test/PGPClearSignedSignatureTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.IO;
 using System.Text;
 
@@ -264,10 +263,9 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
 
 			sGen.InitSign(PgpSignature.CanonicalTextDocument, pgpPrivKey);
 
-			IEnumerator    it = pgpSecKey.PublicKey.GetUserIds().GetEnumerator();
-			if (it.MoveNext())
+			foreach (var userId in pgpSecKey.PublicKey.GetUserIds())
 			{
-				spGen.SetSignerUserId(false, (string)it.Current);
+				spGen.SetSignerUserId(false, userId);
 				sGen.SetHashedSubpackets(spGen.Generate());
 			}
 
diff --git a/crypto/test/src/openpgp/test/PGPDSATest.cs b/crypto/test/src/openpgp/test/PGPDSATest.cs
index 104f5d494..d5ef8b5e9 100644
--- a/crypto/test/src/openpgp/test/PGPDSATest.cs
+++ b/crypto/test/src/openpgp/test/PGPDSATest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.IO;
 using System.Text;
 
@@ -289,9 +288,9 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
 
             PgpSignatureSubpacketGenerator spGen = new PgpSignatureSubpacketGenerator();
 
-            IEnumerator enumerator = sKey.GetSecretKey().PublicKey.GetUserIds().GetEnumerator();
+            var enumerator = sKey.GetSecretKey().PublicKey.GetUserIds().GetEnumerator();
             enumerator.MoveNext();
-            string primaryUserId = (string) enumerator.Current;
+            string primaryUserId = enumerator.Current;
 
             spGen.SetSignerUserId(true, primaryUserId);
 
diff --git a/crypto/test/src/openpgp/test/PGPRSATest.cs b/crypto/test/src/openpgp/test/PGPRSATest.cs
index 534fb8c5d..9d1dedd95 100644
--- a/crypto/test/src/openpgp/test/PGPRSATest.cs
+++ b/crypto/test/src/openpgp/test/PGPRSATest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.IO;
 using System.Text;
 
@@ -539,14 +538,14 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
 
             AsymmetricKeyParameter pubKey = pgpPub.GetPublicKey().GetKey();
 
-            IEnumerator enumerator = pgpPub.GetPublicKey().GetUserIds().GetEnumerator();
-            enumerator.MoveNext();
-            string uid = (string) enumerator.Current;
+            var enumerator1= pgpPub.GetPublicKey().GetUserIds().GetEnumerator();
+            enumerator1.MoveNext();
+            string uid = enumerator1.Current;
 
 
-            enumerator = pgpPub.GetPublicKey().GetSignaturesForId(uid).GetEnumerator();
-            enumerator.MoveNext();
-            PgpSignature sig = (PgpSignature) enumerator.Current;
+            var enumerator2 = pgpPub.GetPublicKey().GetSignaturesForId(uid).GetEnumerator();
+            enumerator2.MoveNext();
+            PgpSignature sig = enumerator2.Current;
 
             sig.InitVerify(pgpPub.GetPublicKey());
 
@@ -830,14 +829,14 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
             PgpPublicKey key = secretKey.PublicKey;
 
 
-            enumerator = key.GetUserIds().GetEnumerator();
-            enumerator.MoveNext();
-            uid = (string) enumerator.Current;
+            var enumerator3 = key.GetUserIds().GetEnumerator();
+            enumerator3.MoveNext();
+            uid = enumerator3.Current;
 
 
-            enumerator = key.GetSignaturesForId(uid).GetEnumerator();
-            enumerator.MoveNext();
-            sig = (PgpSignature) enumerator.Current;
+            var enumerator4 = key.GetSignaturesForId(uid).GetEnumerator();
+            enumerator4.MoveNext();
+            sig = enumerator4.Current;
 
             sig.InitVerify(key);
 
@@ -875,9 +874,9 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
 
             key = tmpRing.GetPublicKey();
 
-            IEnumerator sgEnum = key.GetSignaturesOfType(PgpSignature.KeyRevocation).GetEnumerator();
+            var sgEnum = key.GetSignaturesOfType(PgpSignature.KeyRevocation).GetEnumerator();
             sgEnum.MoveNext();
-            sig = (PgpSignature) sgEnum.Current;
+            sig = sgEnum.Current;
 
             sig.InitVerify(key);
 
@@ -926,14 +925,14 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
             key.Encode(new UncloseableMemoryStream());
 
 
-            enumerator = key.GetUserIds().GetEnumerator();
-            enumerator.MoveNext();
-            uid = (string) enumerator.Current;
+            var enumerator5 = key.GetUserIds().GetEnumerator();
+            enumerator5.MoveNext();
+            uid = enumerator5.Current;
 
 
-            enumerator = key.GetSignaturesForId(uid).GetEnumerator();
-            enumerator.MoveNext();
-            sig = (PgpSignature) enumerator.Current;
+            var enumerator6 = key.GetSignaturesForId(uid).GetEnumerator();
+            enumerator6.MoveNext();
+            sig = enumerator6.Current;
 
             sig.InitVerify(key);
 
diff --git a/crypto/test/src/openpgp/test/PgpECDHTest.cs b/crypto/test/src/openpgp/test/PgpECDHTest.cs
index 711d917a7..aa4fc2117 100644
--- a/crypto/test/src/openpgp/test/PgpECDHTest.cs
+++ b/crypto/test/src/openpgp/test/PgpECDHTest.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.IO;
 using System.Text;
 
@@ -249,9 +249,9 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
             }
         }
 
-        private static object First(IEnumerable e)
+        private static T First<T>(IEnumerable<T> e)
         {
-            IEnumerator n = e.GetEnumerator();
+            var n = e.GetEnumerator();
             Assert.IsTrue(n.MoveNext());
             return n.Current;
         }
diff --git a/crypto/test/src/openpgp/test/PgpECDsaTest.cs b/crypto/test/src/openpgp/test/PgpECDsaTest.cs
index 35e9a2332..c3611d5aa 100644
--- a/crypto/test/src/openpgp/test/PgpECDsaTest.cs
+++ b/crypto/test/src/openpgp/test/PgpECDsaTest.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.IO;
 using System.Text;
 
@@ -176,9 +176,9 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
             }
         }
 
-        private static object First(IEnumerable e)
+        private static T First<T>(IEnumerable<T> e)
         {
-            IEnumerator n = e.GetEnumerator();
+            var n = e.GetEnumerator();
             Assert.IsTrue(n.MoveNext());
             return n.Current;
         }
diff --git a/crypto/test/src/openpgp/test/PgpKeyRingTest.cs b/crypto/test/src/openpgp/test/PgpKeyRingTest.cs
index efc47f881..a5dc4963b 100644
--- a/crypto/test/src/openpgp/test/PgpKeyRingTest.cs
+++ b/crypto/test/src/openpgp/test/PgpKeyRingTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.IO;
 
 using NUnit.Framework;
@@ -2511,7 +2510,7 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
 
             foreach (PgpSecretKeyRing ring in secCol.GetKeyRings())
             {
-                IEnumerator e = ring.GetExtraPublicKeys().GetEnumerator();
+                var e = ring.GetExtraPublicKeys().GetEnumerator();
                 while (e.MoveNext())
                 {
                     ++count;
@@ -2528,13 +2527,13 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp.Tests
             byte[] keyRing)
         {
             PgpPublicKeyRing pubRing = new PgpPublicKeyRing(keyRing);
-            IEnumerator en = pubRing.GetPublicKeys().GetEnumerator();
+            var en = pubRing.GetPublicKeys().GetEnumerator();
 
             if (en.MoveNext())
             {
                 PgpPublicKey key = (PgpPublicKey) en.Current;
 
-                IEnumerator sEn = key.GetSignatures().GetEnumerator();
+                var sEn = key.GetSignatures().GetEnumerator();
 
                 if (sEn.MoveNext())
                 {
diff --git a/crypto/test/src/openpgp/test/PgpSignatureInvalidVersionIgnoredTest.cs b/crypto/test/src/openpgp/test/PgpSignatureInvalidVersionIgnoredTest.cs
index 1cd1385ba..ef64a464a 100644
--- a/crypto/test/src/openpgp/test/PgpSignatureInvalidVersionIgnoredTest.cs
+++ b/crypto/test/src/openpgp/test/PgpSignatureInvalidVersionIgnoredTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.IO;
 using System.Text;
 
diff --git a/crypto/test/src/pkcs/test/PKCS10Test.cs b/crypto/test/src/pkcs/test/PKCS10Test.cs
index 39b33e1b5..949045c8a 100644
--- a/crypto/test/src/pkcs/test/PKCS10Test.cs
+++ b/crypto/test/src/pkcs/test/PKCS10Test.cs
@@ -1,4 +1,4 @@
-using System.Collections;
+using System;
 using System.Collections.Generic;
 
 using NUnit.Framework;
diff --git a/crypto/test/src/pkcs/test/PKCS12StoreTest.cs b/crypto/test/src/pkcs/test/PKCS12StoreTest.cs
index a500e5e63..731070c08 100644
--- a/crypto/test/src/pkcs/test/PKCS12StoreTest.cs
+++ b/crypto/test/src/pkcs/test/PKCS12StoreTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 
diff --git a/crypto/test/src/security/test/TestDotNetUtil.cs b/crypto/test/src/security/test/TestDotNetUtil.cs
index e2bb783ef..82cad46f1 100644
--- a/crypto/test/src/security/test/TestDotNetUtil.cs
+++ b/crypto/test/src/security/test/TestDotNetUtil.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.Security.Cryptography;
 using SystemX509 = System.Security.Cryptography.X509Certificates;
diff --git a/crypto/test/src/security/test/TestEncodings.cs b/crypto/test/src/security/test/TestEncodings.cs
index d83b2dda5..330054e84 100644
--- a/crypto/test/src/security/test/TestEncodings.cs
+++ b/crypto/test/src/security/test/TestEncodings.cs
@@ -1,15 +1,11 @@
 using System;
-using System.Collections;
-using System.Text;
 
 using NUnit.Framework;
 
 using Org.BouncyCastle.Asn1.Pkcs;
 using Org.BouncyCastle.Asn1.X509;
 using Org.BouncyCastle.Crypto;
-using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Parameters;
-using Org.BouncyCastle.Crypto.Signers;
 using Org.BouncyCastle.Math;
 using Org.BouncyCastle.Math.EC;
 using Org.BouncyCastle.Pkcs;
diff --git a/crypto/test/src/security/test/TestSignerUtil.cs b/crypto/test/src/security/test/TestSignerUtil.cs
index f075526b0..2c569d030 100644
--- a/crypto/test/src/security/test/TestSignerUtil.cs
+++ b/crypto/test/src/security/test/TestSignerUtil.cs
@@ -1,20 +1,13 @@
 using System;
-using System.Collections;
-using System.Globalization;
-using System.Text;
 
 using NUnit.Framework;
 
 using Org.BouncyCastle.Asn1.CryptoPro;
-using Org.BouncyCastle.Asn1.Pkcs;
-using Org.BouncyCastle.Asn1.X509;
 using Org.BouncyCastle.Math;
 using Org.BouncyCastle.Math.EC;
 using Org.BouncyCastle.Crypto;
 using Org.BouncyCastle.Crypto.Generators;
 using Org.BouncyCastle.Crypto.Parameters;
-using Org.BouncyCastle.Crypto.Signers;
-using Org.BouncyCastle.Utilities;
 using Org.BouncyCastle.Utilities.Encoders;
 
 namespace Org.BouncyCastle.Security.Tests
@@ -142,11 +135,8 @@ namespace Org.BouncyCastle.Security.Tests
             {
                 ISigner signer = SignerUtilities.GetSigner(algorithm);
 
-#if PORTABLE
                 string upper = algorithm.ToUpperInvariant();
-#else
-                string upper = algorithm.ToUpper(CultureInfo.InvariantCulture);
-#endif
+
                 int withPos = upper.LastIndexOf("WITH");
 
                 string cipherName = withPos < 0
diff --git a/crypto/test/src/test/BlockCipherTest.cs b/crypto/test/src/test/BlockCipherTest.cs
index ff6f45e74..b57d62d94 100644
--- a/crypto/test/src/test/BlockCipherTest.cs
+++ b/crypto/test/src/test/BlockCipherTest.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 
@@ -9,8 +10,6 @@ using Org.BouncyCastle.Crypto;
 using Org.BouncyCastle.Crypto.IO;
 using Org.BouncyCastle.Crypto.Parameters;
 using Org.BouncyCastle.Security;
-using Org.BouncyCastle.Utilities;
-using Org.BouncyCastle.Utilities.Collections;
 using Org.BouncyCastle.Utilities.Encoders;
 using Org.BouncyCastle.Utilities.Test;
 
@@ -24,8 +23,8 @@ namespace Org.BouncyCastle.Tests
     public class BlockCipherTest
         : SimpleTest
     {
-        private static readonly ISet validModes = CollectionUtilities.ReadOnly(
-            new HashSet(new string[]{ "CBC", "CCM", "CFB", "CTR", "CTS", "EAX", "ECB", "GCM", "OCB", "OFB" }));
+        private static readonly ISet<string> ValidModes =
+            new HashSet<string>(){ "CBC", "CCM", "CFB", "CTR", "CTS", "EAX", "ECB", "GCM", "OCB", "OFB" };
 
         private static readonly string[] cipherTests1 =
         {
@@ -436,7 +435,7 @@ namespace Org.BouncyCastle.Tests
             int pos = mode.IndexOfAny(new char[]{ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' });
             string baseMode = pos < 0 ? mode : mode.Substring(0, pos);
 
-            if (!validModes.Contains(baseMode))
+            if (!ValidModes.Contains(baseMode))
                 throw new Exception("Unhandled mode: " + mode);
 
             if (baseMode == "CCM")
diff --git a/crypto/test/src/test/CertPathTest.cs b/crypto/test/src/test/CertPathTest.cs
index 869ffd6a0..be1df89a7 100644
--- a/crypto/test/src/test/CertPathTest.cs
+++ b/crypto/test/src/test/CertPathTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 
diff --git a/crypto/test/src/test/CertPathValidatorTest.cs b/crypto/test/src/test/CertPathValidatorTest.cs
index 88ffe7938..3c4577d59 100644
--- a/crypto/test/src/test/CertPathValidatorTest.cs
+++ b/crypto/test/src/test/CertPathValidatorTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 
 using NUnit.Framework;
diff --git a/crypto/test/src/test/CertTest.cs b/crypto/test/src/test/CertTest.cs
index 7fb2c89c1..b286263a7 100644
--- a/crypto/test/src/test/CertTest.cs
+++ b/crypto/test/src/test/CertTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
@@ -2485,7 +2484,7 @@ namespace Org.BouncyCastle.Tests
 
             MemoryStream input = new MemoryStream(Streams.ReadAll(GetTestDataAsStream("cert_chain.data")), false);
 
-            ISet certs2 = new HashSet();
+            var certs2 = new HashSet<X509Certificate>();
             while (input.Position < input.Length)
             {
                 X509Certificate c = fact.ReadCertificate(input);
@@ -2499,7 +2498,7 @@ namespace Org.BouncyCastle.Tests
             }
             IsTrue("certs size <cr><nl>", certs1.Count == certs2.Count);
 
-            certs2.RemoveAll(certs1);
+            certs2.ExceptWith(certs1);
             IsTrue("collection not empty", certs2.Count == 0);
         }
 
@@ -2523,7 +2522,7 @@ namespace Org.BouncyCastle.Tests
 
             MemoryStream input = new MemoryStream(Streams.ReadAll(GetTestDataAsStream("cert_chain_nl.data")), false);
 
-            ISet certs2 = new HashSet();
+            var certs2 = new HashSet<X509Certificate>();
             while (input.Position < input.Length)
             {
                 X509Certificate c = fact.ReadCertificate(input);
@@ -2537,7 +2536,7 @@ namespace Org.BouncyCastle.Tests
             }
             IsTrue("certs size <nl>", certs1.Count == certs2.Count);
 
-            certs2.RemoveAll(certs1);
+            certs2.ExceptWith(certs1);
             IsTrue("collection not empty", certs2.Count == 0);
         }
 
diff --git a/crypto/test/src/test/NamedCurveTest.cs b/crypto/test/src/test/NamedCurveTest.cs
index c5c3ca74e..7f5332adf 100644
--- a/crypto/test/src/test/NamedCurveTest.cs
+++ b/crypto/test/src/test/NamedCurveTest.cs
@@ -22,8 +22,10 @@ namespace Org.BouncyCastle.Tests
     public class NamedCurveTest
         : SimpleTest
     {
-//		private static readonly Hashtable CurveNames = new Hashtable();
-//		private static readonly Hashtable CurveAliases = new Hashtable();
+//		private static readonly Dictionary<string, sring> CurveNames =
+//		    new Dictionary<string, sring>(StringComparer.OrdinalIgnoreCase);
+//		private static readonly Dictionary<string, sring> CurveAliases =
+//		    new Dictionary<string, sring>(StringComparer.OrdinalIgnoreCase);
 //
 //		static NamedCurveTest()
 //		{
diff --git a/crypto/test/src/test/NistCertPathTest.cs b/crypto/test/src/test/NistCertPathTest.cs
index 42f9895e8..f859ada0a 100644
--- a/crypto/test/src/test/NistCertPathTest.cs
+++ b/crypto/test/src/test/NistCertPathTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.Text;
 
@@ -72,7 +71,7 @@ namespace Org.BouncyCastle.Tests
 		private X509Crl trustedCRL;
 		private ISet<TrustAnchor> trustedSet;
 		private int testCount;
-		private IList testFail;
+		private IList<string> testFail;
 		private StringBuilder resultBuf;
 
 		public override string Name
@@ -268,7 +267,7 @@ namespace Org.BouncyCastle.Tests
 
 				trustedSet.Add(new TrustAnchor(trustedCert, _ncBytes));
 				testCount = 0;
-				testFail = new ArrayList();
+				testFail = new List<string>();
 				resultBuf = new StringBuilder("\n");
 			}
 			catch (Exception ex)
diff --git a/crypto/test/src/test/PKCS10CertRequestTest.cs b/crypto/test/src/test/PKCS10CertRequestTest.cs
index fb913d7de..1ec7c904e 100644
--- a/crypto/test/src/test/PKCS10CertRequestTest.cs
+++ b/crypto/test/src/test/PKCS10CertRequestTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using NUnit.Framework;
 
diff --git a/crypto/test/src/test/PkixPolicyMappingTest.cs b/crypto/test/src/test/PkixPolicyMappingTest.cs
index 5ca33bf6a..4dbfe0ad5 100644
--- a/crypto/test/src/test/PkixPolicyMappingTest.cs
+++ b/crypto/test/src/test/PkixPolicyMappingTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 
 using NUnit.Framework;
diff --git a/crypto/test/src/test/PkixTest.cs b/crypto/test/src/test/PkixTest.cs
index 554d4c64f..5f321022c 100644
--- a/crypto/test/src/test/PkixTest.cs
+++ b/crypto/test/src/test/PkixTest.cs
@@ -1,7 +1,4 @@
 using System;
-using System.IO;
-using System.Collections;
-using System.Text;
 
 using NUnit.Framework;
 
diff --git a/crypto/test/src/test/X509StoreTest.cs b/crypto/test/src/test/X509StoreTest.cs
index 0a5fff6f1..aada53e4e 100644
--- a/crypto/test/src/test/X509StoreTest.cs
+++ b/crypto/test/src/test/X509StoreTest.cs
@@ -1,7 +1,5 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
-using System.IO;
 
 using NUnit.Framework;
 
@@ -137,7 +135,7 @@ namespace Org.BouncyCastle.Tests
 
 			X509CrlStoreSelector targetConstraintsCRL = new X509CrlStoreSelector();
 
-			ArrayList issuers = new ArrayList();
+			var issuers = new List<X509Name>();
 			issuers.Add(rootCrl.IssuerDN);
 			targetConstraintsCRL.Issuers = issuers;
 
diff --git a/crypto/test/src/test/nist/NistCertPathTest.cs b/crypto/test/src/test/nist/NistCertPathTest.cs
index 89565217c..4a6391e8f 100644
--- a/crypto/test/src/test/nist/NistCertPathTest.cs
+++ b/crypto/test/src/test/nist/NistCertPathTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 
@@ -35,8 +34,8 @@ namespace Org.BouncyCastle.Tests.Nist
 		private static readonly string NIST_TEST_POLICY_2 = "2.16.840.1.101.3.2.1.48.2";
 		private static readonly string NIST_TEST_POLICY_3 = "2.16.840.1.101.3.2.1.48.3";
 
-		private static readonly IDictionary certs = new Hashtable();
-        private static readonly IDictionary crls = new Hashtable();
+		private static readonly Dictionary<string, X509Certificate> Certs = new Dictionary<string, X509Certificate>();
+		private static readonly Dictionary<string, X509Crl> Crls = new Dictionary<string, X509Crl>();
 
         private static readonly HashSet<string> noPolicies = new HashSet<string>();
         private static readonly HashSet<string> anyPolicy = new HashSet<string>();
@@ -758,52 +757,28 @@ namespace Org.BouncyCastle.Tests.Nist
 
         private X509Certificate LoadCert(string certName)
         {
-            X509Certificate cert = (X509Certificate)certs[certName];
-            if (null != cert)
-                return cert;
+			if (Certs.TryGetValue(certName, out var cachedCert))
+				return cachedCert;
 
-            Stream fs = null;
-
-            try
-            {
-                fs = SimpleTest.GetTestDataAsStream("PKITS.certs." + certName + ".crt");
-                cert = new X509CertificateParser().ReadCertificate(fs);
-                certs[certName] = cert;
-                return cert;
-            }
-            catch (Exception e)
-            {
-                throw new InvalidOperationException("exception loading certificate " + certName + ": " + e);
-            }
-            finally
+			using (Stream fs = SimpleTest.GetTestDataAsStream("PKITS.certs." + certName + ".crt"))
             {
-                fs.Close();
-            }
+				var cert = new X509CertificateParser().ReadCertificate(fs);
+				Certs[certName] = cert;
+				return cert;
+			}
         }
 
         private X509Crl LoadCrl(string crlName)
         {
-            X509Crl crl = (X509Crl)crls[crlName];
-            if (null != crl)
-                return crl;
-
-            Stream fs = null;
+			if (Crls.TryGetValue(crlName, out var cachedCrl))
+				return cachedCrl;
 
-            try
-            {
-                fs = SimpleTest.GetTestDataAsStream("PKITS.crls." + crlName + ".crl");
-                crl = new X509CrlParser().ReadCrl(fs);
-                crls[crlName] = crl;
-                return crl;
-            }
-            catch (Exception)
-            {
-                throw new InvalidOperationException("exception loading CRL: " + crlName);
-            }
-            finally
-            {
-                fs.Close();
-            }
+			using (Stream fs = SimpleTest.GetTestDataAsStream("PKITS.crls." + crlName + ".crl"))
+			{
+				var crl = new X509CrlParser().ReadCrl(fs);
+				Crls[crlName] = crl;
+				return crl;
+			}
         }
 
 		private TrustAnchor GetTrustAnchor(string trustAnchorName)
diff --git a/crypto/test/src/test/nist/NistCertPathTest2.cs b/crypto/test/src/test/nist/NistCertPathTest2.cs
index 244f9f9c5..1bc40e805 100644
--- a/crypto/test/src/test/nist/NistCertPathTest2.cs
+++ b/crypto/test/src/test/nist/NistCertPathTest2.cs
@@ -1,7 +1,5 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
-using System.IO;
 
 using NUnit.Framework;
 
@@ -28,15 +26,16 @@ namespace Org.BouncyCastle.Tests.Nist
         private static readonly string NIST_TEST_POLICY_2 = "2.16.840.1.101.3.2.1.48.2";
         private static readonly string NIST_TEST_POLICY_3 = "2.16.840.1.101.3.2.1.48.3";
 
-		private static readonly IDictionary certs = new Hashtable();
-		private static readonly IDictionary crls = new Hashtable();
+		private static readonly IDictionary<string, X509Certificate> m_certs =
+            new Dictionary<string, X509Certificate>();
+		private static readonly IDictionary<string, X509Crl> m_crls = new Dictionary<string, X509Crl>();
 
-        private static readonly ISet noPolicies = new HashSet();
-        private static readonly ISet anyPolicy = new HashSet();
-        private static readonly ISet nistTestPolicy1 = new HashSet();
-        private static readonly ISet nistTestPolicy2 = new HashSet();
-        private static readonly ISet nistTestPolicy3 = new HashSet();
-        private static readonly ISet nistTestPolicy1And2 = new HashSet();
+        private static readonly ISet<string> noPolicies = new HashSet<string>();
+        private static readonly ISet<string> anyPolicy = new HashSet<string>();
+        private static readonly ISet<string> nistTestPolicy1 = new HashSet<string>();
+        private static readonly ISet<string> nistTestPolicy2 = new HashSet<string>();
+        private static readonly ISet<string> nistTestPolicy3 = new HashSet<string>();
+        private static readonly ISet<string> nistTestPolicy1And2 = new HashSet<string>();
 
         static NistCertPathTest2()
 		{
@@ -425,52 +424,28 @@ namespace Org.BouncyCastle.Tests.Nist
 
         private X509Certificate LoadCert(string certName)
 		{
-			X509Certificate cert = (X509Certificate)certs[certName];
-			if (null != cert)
-				return cert;
+            if (m_certs.TryGetValue(certName, out var cachedCert))
+                return cachedCert;
 
-            Stream fs = null;
-
-			try
-			{
-				fs = SimpleTest.GetTestDataAsStream("PKITS.certs." + certName + ".crt");
-				cert = new X509CertificateParser().ReadCertificate(fs);
-				certs[certName] = cert;
-				return cert;
-			}
-			catch (Exception e)
-			{
-				throw new InvalidOperationException("exception loading certificate " + certName + ": " + e);
-			}
-			finally
-			{
-				fs.Close();
-			}
+            using (var fs = SimpleTest.GetTestDataAsStream("PKITS.certs." + certName + ".crt"))
+            {
+                var cert = new X509CertificateParser().ReadCertificate(fs);
+                m_certs[certName] = cert;
+                return cert;
+            }
 		}
 
 		private X509Crl LoadCrl(string crlName)
 		{
-			X509Crl crl = (X509Crl)crls[crlName];
-			if (null != crl)
-				return crl;
+            if (m_crls.TryGetValue(crlName, out var cachedCrl))
+                return cachedCrl;
 
-            Stream fs = null;
-
-			try
-			{
-				fs = SimpleTest.GetTestDataAsStream("PKITS.crls." + crlName + ".crl");
-				crl = new X509CrlParser().ReadCrl(fs);
-				crls[crlName] = crl;
-				return crl;
-			}
-			catch (Exception)
-			{
-				throw new InvalidOperationException("exception loading CRL: " + crlName);
-			}
-			finally
-			{
-				fs.Close();
-			}
+            using (var fs = SimpleTest.GetTestDataAsStream("PKITS.crls." + crlName + ".crl"))
+            {
+                var crl = new X509CrlParser().ReadCrl(fs);
+                m_crls[crlName] = crl;
+                return crl;
+            }
 		}
 
         private TrustAnchor GetTrustAnchor(string trustAnchorName)
diff --git a/crypto/test/src/tls/test/MockDatagramAssociation.cs b/crypto/test/src/tls/test/MockDatagramAssociation.cs
index 3e0c0f52b..ef317c7b6 100644
--- a/crypto/test/src/tls/test/MockDatagramAssociation.cs
+++ b/crypto/test/src/tls/test/MockDatagramAssociation.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.Threading;
 
 using Org.BouncyCastle.Utilities;
@@ -15,8 +15,8 @@ namespace Org.BouncyCastle.Tls.Tests
         {
             this.m_mtu = mtu;
 
-            IList clientQueue = new ArrayList();
-            IList serverQueue = new ArrayList();
+            var clientQueue = new List<byte[]>();
+            var serverQueue = new List<byte[]>();
 
             this.m_client = new MockDatagramTransport(this, clientQueue, serverQueue);
             this.m_server = new MockDatagramTransport(this, serverQueue, clientQueue);
@@ -36,9 +36,10 @@ namespace Org.BouncyCastle.Tls.Tests
             : DatagramTransport
         {
             private readonly MockDatagramAssociation m_outer;
-            private IList m_receiveQueue, m_sendQueue;
+            private IList<byte[]> m_receiveQueue, m_sendQueue;
 
-            internal MockDatagramTransport(MockDatagramAssociation outer, IList receiveQueue, IList sendQueue)
+            internal MockDatagramTransport(MockDatagramAssociation outer, IList<byte[]> receiveQueue,
+                IList<byte[]> sendQueue)
             {
                 this.m_outer = outer;
                 this.m_receiveQueue = receiveQueue;
@@ -74,7 +75,7 @@ namespace Org.BouncyCastle.Tls.Tests
                             return -1;
                     }
 
-                    byte[] packet = (byte[])m_receiveQueue[0];
+                    byte[] packet = m_receiveQueue[0];
                     m_receiveQueue.RemoveAt(0);
                     int copyLength = System.Math.Min(len, packet.Length);
                     Array.Copy(packet, 0, buf, off, copyLength);
diff --git a/crypto/test/src/tsp/test/NewTspTest.cs b/crypto/test/src/tsp/test/NewTspTest.cs
index c188cb26a..f6d45ef09 100644
--- a/crypto/test/src/tsp/test/NewTspTest.cs
+++ b/crypto/test/src/tsp/test/NewTspTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.IO;
 
@@ -125,19 +124,19 @@ namespace Org.BouncyCastle.Tsp.Tests
 
 			try
 			{
-				request.Validate(new ArrayList(), new ArrayList(), new ArrayList());
+				request.Validate(new List<string>(), new List<string>(), new List<string>());
 				Assert.Fail("expected exception");
 			} catch(Exception ex)
             {
 				Assert.True("request contains unknown algorithm" == ex.Message);
             }
 
-			ArrayList algorithms = new ArrayList();
+			var algorithms = new List<string>();
 			algorithms.Add(TspAlgorithms.Sha1);
 
 			try
 			{
-				request.Validate(algorithms, new ArrayList(), new ArrayList());
+				request.Validate(algorithms, new List<string>(), new List<string>());
 				Assert.Fail("no exception");
 			}
 			catch (Exception e)
@@ -145,14 +144,14 @@ namespace Org.BouncyCastle.Tsp.Tests
 				Assert.IsTrue(e.Message == "request contains unknown policy");
 			}
 
-			ArrayList policies = new ArrayList();
+			var policies = new List<string>();
 
 			// Testing only do not use in real world.
 			policies.Add("2.5.29.56");
 
 			try
 			{
-				request.Validate(algorithms, policies, new ArrayList());
+				request.Validate(algorithms, policies, new List<string>());
 				Assert.Fail("no exception");
 			}
 			catch (Exception e)
@@ -160,7 +159,7 @@ namespace Org.BouncyCastle.Tsp.Tests
 				Assert.IsTrue(e.Message == "request contains unknown extension");
 			}
 
-			ArrayList extensions = new ArrayList();
+			var extensions = new List<string>();
 
 			// Testing only do not use in real world/
 			extensions.Add("1.3.6.1.5.5.7.1.2");
@@ -197,10 +196,10 @@ namespace Org.BouncyCastle.Tsp.Tests
 			TimeStampRequestGenerator reqGen = new TimeStampRequestGenerator();
 			TimeStampRequest request = reqGen.Generate(TspAlgorithms.Sha1, new byte[20]);
 
-			ArrayList algorithms = new ArrayList();
+			var algorithms = new List<string>();
 			algorithms.Add(TspAlgorithms.Sha1);
 
-			request.Validate(algorithms, new ArrayList(), new ArrayList());
+			request.Validate(algorithms, new List<string>(), new List<string>());
 
 			Assert.False(request.CertReq);
 
@@ -423,7 +422,8 @@ namespace Org.BouncyCastle.Tsp.Tests
 			reqGen.SetReqPolicy("1.1");
 			TimeStampRequest request = reqGen.Generate(TspAlgorithms.Sha1, new byte[20]);
 
-			TimeStampResponseGenerator tsRespGen = new TimeStampResponseGenerator(tsTokenGen, TspAlgorithms.Allowed, new ArrayList());
+			TimeStampResponseGenerator tsRespGen = new TimeStampResponseGenerator(tsTokenGen, TspAlgorithms.Allowed,
+				new List<string>());
 
 			TimeStampResponse tsResp = tsRespGen.Generate(request, BigInteger.ValueOf(23), DateTime.UtcNow);
 
diff --git a/crypto/test/src/tsp/test/TSPTest.cs b/crypto/test/src/tsp/test/TSPTest.cs
index 06c20e4bd..99e11046f 100644
--- a/crypto/test/src/tsp/test/TSPTest.cs
+++ b/crypto/test/src/tsp/test/TSPTest.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 
 using NUnit.Framework;
@@ -267,7 +266,8 @@ namespace Org.BouncyCastle.Tsp.Tests
 
 			TimeStampRequest request = reqGen.Generate(TspAlgorithms.Sha1, new byte[20]);
 
-			TimeStampResponseGenerator tsRespGen = new TimeStampResponseGenerator(tsTokenGen, TspAlgorithms.Allowed, new ArrayList());
+			TimeStampResponseGenerator tsRespGen = new TimeStampResponseGenerator(tsTokenGen, TspAlgorithms.Allowed,
+				new List<string>());
 
 			TimeStampResponse tsResp = tsRespGen.Generate(request, BigInteger.ValueOf(23), DateTime.UtcNow);
 
diff --git a/crypto/test/src/tsp/test/TSPTestUtil.cs b/crypto/test/src/tsp/test/TSPTestUtil.cs
index 20eb7e228..abe153ac1 100644
--- a/crypto/test/src/tsp/test/TSPTestUtil.cs
+++ b/crypto/test/src/tsp/test/TSPTestUtil.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.Text;
 
 using Org.BouncyCastle.Asn1;
@@ -59,18 +59,18 @@ namespace Org.BouncyCastle.Tsp.Tests
 		public static readonly string EncryptionGost3410 = CryptoProObjectIdentifiers.GostR3410x94.Id;
 		public static readonly string EncryptionECGost3410 = CryptoProObjectIdentifiers.GostR3410x2001.Id;
 
-		private static readonly IDictionary encryptionAlgs = new Hashtable();
-		private static readonly IDictionary digestAlgs = new Hashtable();
-		private static readonly IDictionary digestAliases = new Hashtable();
+		private static readonly Dictionary<string, string> EncryptionAlgs = new Dictionary<string, string>();
+		private static readonly Dictionary<string, string> DigestAlgs = new Dictionary<string, string>();
+		private static readonly Dictionary<string, string[]> DigestAliases = new Dictionary<string, string[]>();
 
-		private static readonly ISet noParams = new HashSet();
-		private static readonly IDictionary ecAlgorithms = new Hashtable();
+		private static readonly ISet<string> NoParams = new HashSet<string>();
+		private static readonly Dictionary<string, string> ECAlgorithms = new Dictionary<string, string>();
 
 		private static void AddEntries(DerObjectIdentifier oid, string digest, string encryption)
 		{
 			string alias = oid.Id;
-			digestAlgs.Add(alias, digest);
-			encryptionAlgs.Add(alias, encryption);
+			DigestAlgs.Add(alias, digest);
+			EncryptionAlgs.Add(alias, encryption);
 		}
 
 		static TspTestUtil()
@@ -131,49 +131,49 @@ namespace Org.BouncyCastle.Tsp.Tests
 			AddEntries(EacObjectIdentifiers.id_TA_RSA_PSS_SHA_1, "SHA1", "RSAandMGF1");
 			AddEntries(EacObjectIdentifiers.id_TA_RSA_PSS_SHA_256, "SHA256", "RSAandMGF1");
 
-			encryptionAlgs.Add(X9ObjectIdentifiers.IdDsa.Id, "DSA");
-			encryptionAlgs.Add(PkcsObjectIdentifiers.RsaEncryption.Id, "RSA");
-			encryptionAlgs.Add(TeleTrusTObjectIdentifiers.TeleTrusTRsaSignatureAlgorithm.Id, "RSA");
-			encryptionAlgs.Add(X509ObjectIdentifiers.IdEARsa.Id, "RSA");
-			encryptionAlgs.Add(EncryptionRsaPss, "RSAandMGF1");
-			encryptionAlgs.Add(CryptoProObjectIdentifiers.GostR3410x94.Id, "GOST3410");
-			encryptionAlgs.Add(CryptoProObjectIdentifiers.GostR3410x2001.Id, "ECGOST3410");
-			encryptionAlgs.Add("1.3.6.1.4.1.5849.1.6.2", "ECGOST3410");
-			encryptionAlgs.Add("1.3.6.1.4.1.5849.1.1.5", "GOST3410");
-
-			digestAlgs.Add(PkcsObjectIdentifiers.MD2.Id, "MD2");
-			digestAlgs.Add(PkcsObjectIdentifiers.MD4.Id, "MD4");
-			digestAlgs.Add(PkcsObjectIdentifiers.MD5.Id, "MD5");
-			digestAlgs.Add(OiwObjectIdentifiers.IdSha1.Id, "SHA1");
-			digestAlgs.Add(NistObjectIdentifiers.IdSha224.Id, "SHA224");
-			digestAlgs.Add(NistObjectIdentifiers.IdSha256.Id, "SHA256");
-			digestAlgs.Add(NistObjectIdentifiers.IdSha384.Id, "SHA384");
-			digestAlgs.Add(NistObjectIdentifiers.IdSha512.Id, "SHA512");
-			digestAlgs.Add(TeleTrusTObjectIdentifiers.RipeMD128.Id, "RIPEMD128");
-			digestAlgs.Add(TeleTrusTObjectIdentifiers.RipeMD160.Id, "RIPEMD160");
-			digestAlgs.Add(TeleTrusTObjectIdentifiers.RipeMD256.Id, "RIPEMD256");
-			digestAlgs.Add(CryptoProObjectIdentifiers.GostR3411.Id, "GOST3411");
-			digestAlgs.Add("1.3.6.1.4.1.5849.1.2.1", "GOST3411");
-
-			digestAliases.Add("SHA1", new string[] { "SHA-1" });
-			digestAliases.Add("SHA224", new string[] { "SHA-224" });
-			digestAliases.Add("SHA256", new string[] { "SHA-256" });
-			digestAliases.Add("SHA384", new string[] { "SHA-384" });
-			digestAliases.Add("SHA512", new string[] { "SHA-512" });
-
-			noParams.Add(EncryptionDsa);
+			EncryptionAlgs.Add(X9ObjectIdentifiers.IdDsa.Id, "DSA");
+			EncryptionAlgs.Add(PkcsObjectIdentifiers.RsaEncryption.Id, "RSA");
+			EncryptionAlgs.Add(TeleTrusTObjectIdentifiers.TeleTrusTRsaSignatureAlgorithm.Id, "RSA");
+			EncryptionAlgs.Add(X509ObjectIdentifiers.IdEARsa.Id, "RSA");
+			EncryptionAlgs.Add(EncryptionRsaPss, "RSAandMGF1");
+			EncryptionAlgs.Add(CryptoProObjectIdentifiers.GostR3410x94.Id, "GOST3410");
+			EncryptionAlgs.Add(CryptoProObjectIdentifiers.GostR3410x2001.Id, "ECGOST3410");
+			EncryptionAlgs.Add("1.3.6.1.4.1.5849.1.6.2", "ECGOST3410");
+			EncryptionAlgs.Add("1.3.6.1.4.1.5849.1.1.5", "GOST3410");
+
+			DigestAlgs.Add(PkcsObjectIdentifiers.MD2.Id, "MD2");
+			DigestAlgs.Add(PkcsObjectIdentifiers.MD4.Id, "MD4");
+			DigestAlgs.Add(PkcsObjectIdentifiers.MD5.Id, "MD5");
+			DigestAlgs.Add(OiwObjectIdentifiers.IdSha1.Id, "SHA1");
+			DigestAlgs.Add(NistObjectIdentifiers.IdSha224.Id, "SHA224");
+			DigestAlgs.Add(NistObjectIdentifiers.IdSha256.Id, "SHA256");
+			DigestAlgs.Add(NistObjectIdentifiers.IdSha384.Id, "SHA384");
+			DigestAlgs.Add(NistObjectIdentifiers.IdSha512.Id, "SHA512");
+			DigestAlgs.Add(TeleTrusTObjectIdentifiers.RipeMD128.Id, "RIPEMD128");
+			DigestAlgs.Add(TeleTrusTObjectIdentifiers.RipeMD160.Id, "RIPEMD160");
+			DigestAlgs.Add(TeleTrusTObjectIdentifiers.RipeMD256.Id, "RIPEMD256");
+			DigestAlgs.Add(CryptoProObjectIdentifiers.GostR3411.Id, "GOST3411");
+			DigestAlgs.Add("1.3.6.1.4.1.5849.1.2.1", "GOST3411");
+
+			DigestAliases.Add("SHA1", new string[] { "SHA-1" });
+			DigestAliases.Add("SHA224", new string[] { "SHA-224" });
+			DigestAliases.Add("SHA256", new string[] { "SHA-256" });
+			DigestAliases.Add("SHA384", new string[] { "SHA-384" });
+			DigestAliases.Add("SHA512", new string[] { "SHA-512" });
+
+			NoParams.Add(EncryptionDsa);
 			//noParams.Add(EncryptionECDsa);
-			noParams.Add(EncryptionECDsaWithSha1);
-			noParams.Add(EncryptionECDsaWithSha224);
-			noParams.Add(EncryptionECDsaWithSha256);
-			noParams.Add(EncryptionECDsaWithSha384);
-			noParams.Add(EncryptionECDsaWithSha512);
-
-			ecAlgorithms.Add(DigestSha1, EncryptionECDsaWithSha1);
-			ecAlgorithms.Add(DigestSha224, EncryptionECDsaWithSha224);
-			ecAlgorithms.Add(DigestSha256, EncryptionECDsaWithSha256);
-			ecAlgorithms.Add(DigestSha384, EncryptionECDsaWithSha384);
-			ecAlgorithms.Add(DigestSha512, EncryptionECDsaWithSha512);
+			NoParams.Add(EncryptionECDsaWithSha1);
+			NoParams.Add(EncryptionECDsaWithSha224);
+			NoParams.Add(EncryptionECDsaWithSha256);
+			NoParams.Add(EncryptionECDsaWithSha384);
+			NoParams.Add(EncryptionECDsaWithSha512);
+
+			ECAlgorithms.Add(DigestSha1, EncryptionECDsaWithSha1);
+			ECAlgorithms.Add(DigestSha224, EncryptionECDsaWithSha224);
+			ECAlgorithms.Add(DigestSha256, EncryptionECDsaWithSha256);
+			ECAlgorithms.Add(DigestSha384, EncryptionECDsaWithSha384);
+			ECAlgorithms.Add(DigestSha512, EncryptionECDsaWithSha512);
 		}
 
 		public static string DumpBase64(
@@ -187,13 +187,12 @@ namespace Org.BouncyCastle.Tsp.Tests
 			{
 				if (i + 64 < data.Length)
 				{
-					buf.Append(Encoding.ASCII.GetString(data, i, 64));
+					buf.AppendLine(Encoding.ASCII.GetString(data, i, 64));
 				}
 				else
 				{
-					buf.Append(Encoding.ASCII.GetString(data, i, data.Length - i));
+					buf.AppendLine(Encoding.ASCII.GetString(data, i, data.Length - i));
 				}
-				buf.Append('\n');
 			}
 
 			return buf.ToString();
@@ -201,33 +200,17 @@ namespace Org.BouncyCastle.Tsp.Tests
 
 		public static string GetDigestAlgName(string digestAlgOid)
 		{
-			string algName = (string)digestAlgs[digestAlgOid];
-
-			if (algName != null)
-			{
-				return algName;
-			}
-
-			return digestAlgOid;
+			return CollectionUtilities.GetValueOrKey(DigestAlgs, digestAlgOid);
 		}
 
 		public static string GetEncryptionAlgName(string encryptionAlgOid)
 		{
-			string algName = (string)encryptionAlgs[encryptionAlgOid];
-
-			if (algName != null)
-			{
-				return algName;
-			}
-
-			return encryptionAlgOid;
+			return CollectionUtilities.GetValueOrKey(EncryptionAlgs, encryptionAlgOid);
 		}
 
-		internal static string GetEncOid(
-			AsymmetricKeyParameter key,
-			string digestOID)
+		internal static string GetEncOid(AsymmetricKeyParameter key, string digestOID)
 		{
-			string encOID = null;
+			string encOID;
 
 			if (key is RsaKeyParameters)
 			{
@@ -275,9 +258,7 @@ namespace Org.BouncyCastle.Tsp.Tests
 				else
 				{
 					// TODO Should we insist on algName being one of "EC" or "ECDSA", as Java does?
-					encOID = (string)ecAlgorithms[digestOID];
-
-					if (encOID == null)
+					if (!ECAlgorithms.TryGetValue(digestOID, out encOID))
 						throw new ArgumentException("can't mix ECDSA with anything but SHA family digests");
 				}
 			}
diff --git a/crypto/test/src/util/io/pem/test/AllTests.cs b/crypto/test/src/util/io/pem/test/AllTests.cs
index 9a413450d..88ccf2e40 100644
--- a/crypto/test/src/util/io/pem/test/AllTests.cs
+++ b/crypto/test/src/util/io/pem/test/AllTests.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.IO;
 
 using NUnit.Framework;
@@ -14,20 +14,20 @@ namespace Org.BouncyCastle.Utilities.IO.Pem.Tests
 		{
 			for (int i = 1; i != 60; i++)
 			{
-				LengthTest("CERTIFICATE", new ArrayList(), new byte[i]);
+				LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[i]);
 			}
 
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[100]);
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[101]);
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[102]);
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[103]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[100]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[101]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[102]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[103]);
 
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[1000]);
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[1001]);
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[1002]);
-			LengthTest("CERTIFICATE", new ArrayList(), new byte[1003]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[1000]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[1001]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[1002]);
+			LengthTest("CERTIFICATE", new List<PemHeader>(), new byte[1003]);
 
-			IList headers = new ArrayList();
+			var headers = new List<PemHeader>();
 			headers.Add(new PemHeader("Proc-Type", "4,ENCRYPTED"));
 			headers.Add(new PemHeader("DEK-Info", "DES3,0001020304050607"));
 			LengthTest("RSA PRIVATE KEY", headers, new byte[103]);
@@ -48,7 +48,7 @@ namespace Org.BouncyCastle.Utilities.IO.Pem.Tests
             }
         }
 
-		private void LengthTest(string type, IList headers, byte[] data)
+		private void LengthTest(string type, IList<PemHeader> headers, byte[] data)
 		{
 			StringWriter sw = new StringWriter();
 			PemWriter pWrt = new PemWriter(sw);
diff --git a/crypto/test/src/util/test/SimpleTest.cs b/crypto/test/src/util/test/SimpleTest.cs
index 1695164e5..91c493ef7 100644
--- a/crypto/test/src/util/test/SimpleTest.cs
+++ b/crypto/test/src/util/test/SimpleTest.cs
@@ -1,5 +1,5 @@
 using System;
-using System.Collections;
+using System.Collections.Generic;
 using System.IO;
 using System.Reflection;
 
@@ -148,7 +148,7 @@ namespace Org.BouncyCastle.Utilities.Test
 		{
 			string fullPrefix = GetFullName(prefix);
 
-			ArrayList result = new ArrayList();
+			var result = new List<string>();
 			string[] fullNames = GetAssembly().GetManifestResourceNames();
 			foreach (string fullName in fullNames)
 			{
@@ -158,7 +158,7 @@ namespace Org.BouncyCastle.Utilities.Test
 					result.Add(name);
 				}
 			}
-			return (string[])result.ToArray(typeof(string));
+            return result.ToArray();
 		}
 
         private static Assembly GetAssembly()
diff --git a/crypto/test/src/x509/test/TestCertificateGen.cs b/crypto/test/src/x509/test/TestCertificateGen.cs
index d1ac173bc..f4dc5cc01 100644
--- a/crypto/test/src/x509/test/TestCertificateGen.cs
+++ b/crypto/test/src/x509/test/TestCertificateGen.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 
 using NUnit.Framework;