Asn1 GetInstance refactoring

24 files changed, 289 insertions, 248 deletions

diff --git a/crypto/src/asn1/Asn1Null.cs b/crypto/src/asn1/Asn1Null.cs
index 9ea9b4375..77304c0fb 100644
--- a/crypto/src/asn1/Asn1Null.cs
+++ b/crypto/src/asn1/Asn1Null.cs
@@ -25,21 +25,23 @@ namespace Org.BouncyCastle.Asn1
 
         public static Asn1Null GetInstance(object obj)
         {
-            if (obj == null || obj is Asn1Null)
-            {
-                return (Asn1Null)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is Asn1Null asn1Null)
+                return asn1Null;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is Asn1Null)
-                    return (Asn1Null)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is Asn1Null converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (Asn1Null)Meta.Instance.FromByteArray((byte[])obj);
+                    return (Asn1Null)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/Asn1ObjectDescriptor.cs b/crypto/src/asn1/Asn1ObjectDescriptor.cs
index 9c99f441e..13521a744 100644
--- a/crypto/src/asn1/Asn1ObjectDescriptor.cs
+++ b/crypto/src/asn1/Asn1ObjectDescriptor.cs
@@ -36,21 +36,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static Asn1ObjectDescriptor GetInstance(object obj)
         {
-            if (obj == null || obj is Asn1ObjectDescriptor)
-            {
-                return (Asn1ObjectDescriptor)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is Asn1ObjectDescriptor asn1ObjectDescriptor)
+                return asn1ObjectDescriptor;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is Asn1ObjectDescriptor)
-                    return (Asn1ObjectDescriptor)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is Asn1ObjectDescriptor converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (Asn1ObjectDescriptor)Meta.Instance.FromByteArray((byte[])obj);
+                    return (Asn1ObjectDescriptor)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/Asn1OctetString.cs b/crypto/src/asn1/Asn1OctetString.cs
index d34686134..8f7da8800 100644
--- a/crypto/src/asn1/Asn1OctetString.cs
+++ b/crypto/src/asn1/Asn1OctetString.cs
@@ -36,22 +36,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static Asn1OctetString GetInstance(object obj)
         {
-            if (obj == null || obj is Asn1OctetString)
-            {
-                return (Asn1OctetString)obj;
-            }
-            //else if (obj is Asn1OctetStringParser)
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is Asn1OctetString asn1OctetString)
+                return asn1OctetString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is Asn1OctetString)
-                    return (Asn1OctetString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is Asn1OctetString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (Asn1OctetString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (Asn1OctetString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/Asn1RelativeOid.cs b/crypto/src/asn1/Asn1RelativeOid.cs
index a1997864d..3c4bf237a 100644
--- a/crypto/src/asn1/Asn1RelativeOid.cs
+++ b/crypto/src/asn1/Asn1RelativeOid.cs
@@ -29,21 +29,23 @@ namespace Org.BouncyCastle.Asn1
 
         public static Asn1RelativeOid GetInstance(object obj)
         {
-            if (obj == null || obj is Asn1RelativeOid)
-            {
-                return (Asn1RelativeOid)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is Asn1RelativeOid asn1RelativeOid)
+                return asn1RelativeOid;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is Asn1RelativeOid)
-                    return (Asn1RelativeOid)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is Asn1RelativeOid converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (Asn1RelativeOid)FromByteArray((byte[])obj);
+                    return (Asn1RelativeOid)FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/Asn1Sequence.cs b/crypto/src/asn1/Asn1Sequence.cs
index 1a123e26d..a8191de99 100644
--- a/crypto/src/asn1/Asn1Sequence.cs
+++ b/crypto/src/asn1/Asn1Sequence.cs
@@ -30,22 +30,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static Asn1Sequence GetInstance(object obj)
         {
-            if (obj == null || obj is Asn1Sequence)
-            {
-                return (Asn1Sequence)obj;
-            }
-            //else if (obj is Asn1SequenceParser)
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is Asn1Sequence asn1Sequence)
+                return asn1Sequence;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is Asn1Sequence)
-                    return (Asn1Sequence)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is Asn1Sequence converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (Asn1Sequence)Meta.Instance.FromByteArray((byte[])obj);
+                    return (Asn1Sequence)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/Asn1Set.cs b/crypto/src/asn1/Asn1Set.cs
index faec50eb0..2b3810e43 100644
--- a/crypto/src/asn1/Asn1Set.cs
+++ b/crypto/src/asn1/Asn1Set.cs
@@ -31,22 +31,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static Asn1Set GetInstance(object obj)
         {
-            if (obj == null || obj is Asn1Set)
-            {
-                return (Asn1Set)obj;
-            }
-            //else if (obj is Asn1SetParser)
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is Asn1Set asn1Set)
+                return asn1Set;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is Asn1Set)
-                    return (Asn1Set)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is Asn1Set converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (Asn1Set)Meta.Instance.FromByteArray((byte[])obj);
+                    return (Asn1Set)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/Asn1TaggedObject.cs b/crypto/src/asn1/Asn1TaggedObject.cs
index 46aa137a8..63ab6a5d0 100644
--- a/crypto/src/asn1/Asn1TaggedObject.cs
+++ b/crypto/src/asn1/Asn1TaggedObject.cs
@@ -21,22 +21,23 @@ namespace Org.BouncyCastle.Asn1
 
         public static Asn1TaggedObject GetInstance(object obj)
 		{
-            if (obj == null || obj is Asn1TaggedObject) 
-            {
-                return (Asn1TaggedObject)obj;
-            }
-            //else if (obj is Asn1TaggedObjectParser)
-            else if (obj is IAsn1Convertible asn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is Asn1TaggedObject asn1TaggedObject)
+                return asn1TaggedObject;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
                 Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
-                if (asn1Object is Asn1TaggedObject taggedObject)
-                    return taggedObject;
+                if (asn1Object is Asn1TaggedObject converted)
+                    return converted;
             }
-            else if (obj is byte[] byteArray)
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return CheckedCast(FromByteArray(byteArray));
+                    return CheckedCast(FromByteArray(bytes));
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DERExternal.cs b/crypto/src/asn1/DERExternal.cs
index 9fba95165..207930062 100644
--- a/crypto/src/asn1/DERExternal.cs
+++ b/crypto/src/asn1/DERExternal.cs
@@ -25,21 +25,23 @@ namespace Org.BouncyCastle.Asn1
 
         public static DerExternal GetInstance(object obj)
         {
-            if (obj == null || obj is DerExternal)
-            {
-                return (DerExternal)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerExternal derExternal)
+                return derExternal;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerExternal)
-                    return (DerExternal)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerExternal converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerExternal)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerExternal)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerBMPString.cs b/crypto/src/asn1/DerBMPString.cs
index a289eed1b..284a4b830 100644
--- a/crypto/src/asn1/DerBMPString.cs
+++ b/crypto/src/asn1/DerBMPString.cs
@@ -31,21 +31,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerBmpString GetInstance(object obj)
         {
-            if (obj == null || obj is DerBmpString)
-            {
-                return (DerBmpString)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerBmpString derBmpString)
+                return derBmpString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerBmpString)
-                    return (DerBmpString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerBmpString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerBmpString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerBmpString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerBitString.cs b/crypto/src/asn1/DerBitString.cs
index 8aab88353..44b3bb95a 100644
--- a/crypto/src/asn1/DerBitString.cs
+++ b/crypto/src/asn1/DerBitString.cs
@@ -38,22 +38,23 @@ namespace Org.BouncyCastle.Asn1
 		 */
 		public static DerBitString GetInstance(object obj)
 		{
-			if (obj == null || obj is DerBitString)
-			{
-				return (DerBitString)obj;
-			}
-            //else if (obj is Asn1BitStringParser)
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+			if (obj is DerBitString derBitString)
+				return derBitString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerBitString)
-                    return (DerBitString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerBitString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return GetInstance(FromByteArray((byte[])obj));
+                    return GetInstance(FromByteArray(bytes));
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerBoolean.cs b/crypto/src/asn1/DerBoolean.cs
index ad578ae80..6256db6e0 100644
--- a/crypto/src/asn1/DerBoolean.cs
+++ b/crypto/src/asn1/DerBoolean.cs
@@ -30,21 +30,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerBoolean GetInstance(object obj)
         {
-            if (obj == null || obj is DerBoolean)
-            {
-                return (DerBoolean)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerBoolean derBoolean)
+                return derBoolean;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerBoolean)
-                    return (DerBoolean)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerBoolean converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerBoolean)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerBoolean)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerEnumerated.cs b/crypto/src/asn1/DerEnumerated.cs
index 920b3dc8e..b85c5a43e 100644
--- a/crypto/src/asn1/DerEnumerated.cs
+++ b/crypto/src/asn1/DerEnumerated.cs
@@ -28,21 +28,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerEnumerated GetInstance(object obj)
         {
-            if (obj == null || obj is DerEnumerated)
-            {
-                return (DerEnumerated)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerEnumerated derEnumerated)
+                return derEnumerated;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerEnumerated)
-                    return (DerEnumerated)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerEnumerated converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerEnumerated)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerEnumerated)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerGeneralString.cs b/crypto/src/asn1/DerGeneralString.cs
index e6637732a..6a378307d 100644
--- a/crypto/src/asn1/DerGeneralString.cs
+++ b/crypto/src/asn1/DerGeneralString.cs
@@ -22,21 +22,23 @@ namespace Org.BouncyCastle.Asn1
 
         public static DerGeneralString GetInstance(object obj)
         {
-            if (obj == null || obj is DerGeneralString)
-            {
-                return (DerGeneralString) obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerGeneralString derGeneralString)
+                return derGeneralString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerGeneralString)
-                    return (DerGeneralString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerGeneralString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerGeneralString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerGeneralString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerGraphicString.cs b/crypto/src/asn1/DerGraphicString.cs
index cb32d14eb..85330eb33 100644
--- a/crypto/src/asn1/DerGraphicString.cs
+++ b/crypto/src/asn1/DerGraphicString.cs
@@ -29,21 +29,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerGraphicString GetInstance(object obj)
         {
-            if (obj == null || obj is DerGraphicString)
-            {
-                return (DerGraphicString)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerGraphicString derGraphicString)
+                return derGraphicString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerGraphicString)
-                    return (DerGraphicString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerGraphicString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerGraphicString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerGraphicString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerIA5String.cs b/crypto/src/asn1/DerIA5String.cs
index a56879831..de2860130 100644
--- a/crypto/src/asn1/DerIA5String.cs
+++ b/crypto/src/asn1/DerIA5String.cs
@@ -30,21 +30,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerIA5String GetInstance(object obj)
         {
-            if (obj == null || obj is DerIA5String)
-            {
-                return (DerIA5String)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerIA5String derIA5String)
+                return derIA5String;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerIA5String)
-                    return (DerIA5String)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerIA5String converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerIA5String)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerIA5String)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerInteger.cs b/crypto/src/asn1/DerInteger.cs
index c8d4e47df..05a790743 100644
--- a/crypto/src/asn1/DerInteger.cs
+++ b/crypto/src/asn1/DerInteger.cs
@@ -42,21 +42,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerInteger GetInstance(object obj)
         {
-            if (obj == null || obj is DerInteger)
-            {
-                return (DerInteger)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerInteger derInteger)
+                return derInteger;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerInteger)
-                    return (DerInteger)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerInteger converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerInteger)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerInteger)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerNumericString.cs b/crypto/src/asn1/DerNumericString.cs
index 693ff7d6e..819d946b1 100644
--- a/crypto/src/asn1/DerNumericString.cs
+++ b/crypto/src/asn1/DerNumericString.cs
@@ -30,21 +30,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerNumericString GetInstance(object obj)
         {
-            if (obj == null || obj is DerNumericString)
-            {
-                return (DerNumericString)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerNumericString derNumericString)
+                return derNumericString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerNumericString)
-                    return (DerNumericString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerNumericString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerNumericString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerNumericString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerObjectIdentifier.cs b/crypto/src/asn1/DerObjectIdentifier.cs
index b10f8f8b6..cb5771958 100644
--- a/crypto/src/asn1/DerObjectIdentifier.cs
+++ b/crypto/src/asn1/DerObjectIdentifier.cs
@@ -34,21 +34,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerObjectIdentifier GetInstance(object obj)
         {
-            if (obj == null || obj is DerObjectIdentifier)
-            {
-                return (DerObjectIdentifier)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerObjectIdentifier derObjectIdentifier)
+                return derObjectIdentifier;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerObjectIdentifier)
-                    return (DerObjectIdentifier)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerObjectIdentifier converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerObjectIdentifier)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerObjectIdentifier)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerPrintableString.cs b/crypto/src/asn1/DerPrintableString.cs
index 3c44a2d52..5830afa47 100644
--- a/crypto/src/asn1/DerPrintableString.cs
+++ b/crypto/src/asn1/DerPrintableString.cs
@@ -30,21 +30,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerPrintableString GetInstance(object obj)
         {
-            if (obj == null || obj is DerPrintableString)
-            {
-                return (DerPrintableString)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerPrintableString derPrintableString)
+                return derPrintableString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerPrintableString)
-                    return (DerPrintableString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerPrintableString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerPrintableString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerPrintableString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerT61String.cs b/crypto/src/asn1/DerT61String.cs
index a0e4f1d22..45f57ae0a 100644
--- a/crypto/src/asn1/DerT61String.cs
+++ b/crypto/src/asn1/DerT61String.cs
@@ -30,21 +30,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerT61String GetInstance(object obj)
         {
-            if (obj == null || obj is DerT61String)
-            {
-                return (DerT61String)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerT61String derT61String)
+                return derT61String;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerT61String)
-                    return (DerT61String)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerT61String converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerT61String)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerT61String)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerUTF8String.cs b/crypto/src/asn1/DerUTF8String.cs
index d15a19d39..9472f5082 100644
--- a/crypto/src/asn1/DerUTF8String.cs
+++ b/crypto/src/asn1/DerUTF8String.cs
@@ -30,21 +30,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerUtf8String GetInstance(object obj)
         {
-            if (obj == null || obj is DerUtf8String)
-            {
-                return (DerUtf8String)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerUtf8String derUtf8String)
+                return derUtf8String;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerUtf8String)
-                    return (DerUtf8String)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerUtf8String converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerUtf8String)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerUtf8String)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerUniversalString.cs b/crypto/src/asn1/DerUniversalString.cs
index e4e93bd7d..1183ed1f3 100644
--- a/crypto/src/asn1/DerUniversalString.cs
+++ b/crypto/src/asn1/DerUniversalString.cs
@@ -32,24 +32,25 @@ namespace Org.BouncyCastle.Asn1
          *
          * @exception ArgumentException if the object cannot be converted.
          */
-        public static DerUniversalString GetInstance(
-            object obj)
+        public static DerUniversalString GetInstance(object obj)
         {
-            if (obj == null || obj is DerUniversalString)
-            {
-                return (DerUniversalString)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerUniversalString derUniversalString)
+                return derUniversalString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerUniversalString)
-                    return (DerUniversalString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerUniversalString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerUniversalString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerUniversalString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerVideotexString.cs b/crypto/src/asn1/DerVideotexString.cs
index a5fbe0602..636af0499 100644
--- a/crypto/src/asn1/DerVideotexString.cs
+++ b/crypto/src/asn1/DerVideotexString.cs
@@ -29,21 +29,23 @@ namespace Org.BouncyCastle.Asn1
          */
         public static DerVideotexString GetInstance(object obj)
         {
-            if (obj == null || obj is DerVideotexString)
-            {
-                return (DerVideotexString)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerVideotexString derVideotexString)
+                return derVideotexString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerVideotexString)
-                    return (DerVideotexString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerVideotexString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerVideotexString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerVideotexString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {
diff --git a/crypto/src/asn1/DerVisibleString.cs b/crypto/src/asn1/DerVisibleString.cs
index 359370040..77fe54c9a 100644
--- a/crypto/src/asn1/DerVisibleString.cs
+++ b/crypto/src/asn1/DerVisibleString.cs
@@ -28,24 +28,25 @@ namespace Org.BouncyCastle.Asn1
          *
          * @exception ArgumentException if the object cannot be converted.
          */
-        public static DerVisibleString GetInstance(
-            object obj)
+        public static DerVisibleString GetInstance(object obj)
         {
-            if (obj == null || obj is DerVisibleString)
-            {
-                return (DerVisibleString)obj;
-            }
-            else if (obj is IAsn1Convertible)
+            if (obj == null)
+                return null;
+
+            if (obj is DerVisibleString derVisibleString)
+                return derVisibleString;
+
+            if (obj is IAsn1Convertible asn1Convertible)
             {
-                Asn1Object asn1Object = ((IAsn1Convertible)obj).ToAsn1Object();
-                if (asn1Object is DerVisibleString)
-                    return (DerVisibleString)asn1Object;
+                Asn1Object asn1Object = asn1Convertible.ToAsn1Object();
+                if (asn1Object is DerVisibleString converted)
+                    return converted;
             }
-            else if (obj is byte[])
+            else if (obj is byte[] bytes)
             {
                 try
                 {
-                    return (DerVisibleString)Meta.Instance.FromByteArray((byte[])obj);
+                    return (DerVisibleString)Meta.Instance.FromByteArray(bytes);
                 }
                 catch (IOException e)
                 {